Performance information

• Silyliumylidene Ion Stabilized by Two σ‐Donating Ni(0)‐ and Pd(0)‐Fragments　　　　　　　　　　　　　　　
  Shintaro Takahashi; Yugo Kazama; Norio Nakata; Antoine Baceiredo; Daisuke Hashizume; Nathalie Saffon‐Merceron; Vicenç Branchadell; Tsuyoshi Kato
  Chemistry – A European Journal, May 2024
  Abstract
  
  A silyliumylidene ion 2 stabilized by two σ‐donating Ni(0)‐ and Pd(0)‐fragments was successfully synthesized. Due to the σ‐donation of M→Si interactions, 2 presents a pyramidalized cationic silicon center with a localized lone pair. The additional coordination of basic Pd(0) fragment to the mono‐Ni(0)‐stabilized silyliumylidene 1 results in a higher HOMO level and an unchanged HOMO‐LUMO gap and thus, 2 remains highly reactive. Interestingly, the coordination mode at the Si center is closely related to the nature of M‐ligands. Indeed, the donor/donor‐stabilized silyliumylidene ion 2 has been transformed into a donor/acceptor‐stabilized ion 13, featuring a trigonal planar Si center with a vacant orbital, just via a ligand exchange reaction from PCy₃/NHC toward PMe₃.
  Wiley, Scientific journal
  DOI：https://doi.org/10.1002/chem.202400054
  DOI ID：10.1002/chem.202400054, ISSN：0947-6539, eISSN：1521-3765
• (N,N′-Di-tert-butyl-S-phenylsulfinimidamidato-κN,κN′)-chlorogermanium-κGe-chloro(η²,η²-cycloocta-1,5-diene)rhodium
  Narimi Hosoda; Akihiko Ishii; Norio Nakata
  Molbank, Volume：2024, Number：1, Feb. 2024
  The title complex [{PhS(tBuN)2}(Cl)Ge:→RhCl(cod)] (2) was synthesized by the reaction of three-coordinated chlorogermylene, [PhS(tBuN)2]GeCl (1), supported by a diimidosulfinate ligand with a half equivalent of [RhCl(cod)]2 in benzene. The molecular structure of 2 was determined by 1H and 13C NMR spectroscopies and single-crystal X-ray diffraction (SCXRD) analysis. The electronic property of germylene 1 was assessed by determining the Tolman electronic parameter of the corresponding cis-dicarbonyl Rh(I) complex, [{PhS(tBuN)2}(Cl)Ge:→RhCl(CO)2] (3), that was prepared by the treatment of 2 with carbon monoxide.
  DOI：https://doi.org/10.3390/M1781
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  DOI ID：10.3390/M1781, eISSN：1422-8599, ORCID：154559471, SCOPUS ID：85189161724
• Isospecific polymerization of sterically bulky α-olefins catalyzed by zirconium(IV) complex possessing an [OSSO]-type bis(phenolate) ligand　　　　　　　　　　　　　　　
  Nagisa Ueda; Kakeru Maeda; Akihiko Ishii; Norio Nakata
  Journal of Polymer Science, Volume：62, Number：1, First page：125, Last page：131, Jan. 2024
  Dibenzyl zirconium(IV) complex (1), featuring an [OSSO]-type bis(phenolate) ligand, served as a highly efficient pre-catalyst for the polymerization of sterically bulky α-olefins, such as vinyl cyclohexane (VCH) and 3-methyl-1-butene (3-MB). Upon activation with dried modified-methylaluminoxane (dMMAO), the polymerization of VCH proceeded smoothly at 25°C to yield exclusively isotactic poly(VCH)s ([mm] >95%, Mw = 6500–19,400 g mol−1, PDI = 1.4), exhibiting good activity up to 924 g mmol(1)−1 h−1. The 1/dMMAO catalyst system also facilitated the polymerization of 3-MB, producing colorless insoluble poly(3-MB)s. DSC, TGA, and 13C CP-MAS analyses showed the presence of highly isotactic microstructures in the resulting poly(3-MB)s. Remarkably, the corresponding activity reached an impressive value of 898 g mmol(1)−1 h−1, surpassing that of previously reported homogeneous catalysts.
  Scientific journal
  DOI：https://doi.org/10.1002/pol.20230617
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  DOI ID：10.1002/pol.20230617, ISSN：2642-4150, eISSN：2642-4169, SCOPUS ID：85174405899
• Syntheses of Iminophosphomamido Chlorogermylenes and their Complexation with Rhodium(I) Complex　　　　　　　　　　　　　　　
  Shintaro Takahashi; Shota Kamiyama; Akihiko Ishii; Norio Nakata
  Chemistry – An Asian Journal, Volume：19, Number：4, Dec. 2023
  Three‐coordinated chlorogermylenes of the type [Ph2P(RN)2]GeCl (3: R = tBu; 4: R = Dip = 2,6‐iPr2C6H3), which bear an N,N‐substituted iminophosphonamide ligand, were synthesized. The coordination behavior of 3 and 4 toward rhodium(I) complex was investigated. When 3 was treated with 1/2 of an equivalent of [RhCl(cod)]2 (cod = 1,5‐cyclooctadiene), the corresponding chlorogermylene‐Rh(I) complex 5 was obtained as orange crystals. In contrast, the reaction of 4 with a half equivalent of [RhCl(cod)]2 under a CO atmosphere resulted in the formation of a five‐membered germarhodacycle 7. Compounds 3, 4, 5, and 7 were characterized using NMR spectroscopies and single‐crystal X‐ray diffraction. Complex 5 can be employed as a catalyst for the hydrosilylation and hydroboration reactions of diphenylacetylene, thus demonstrating the utility of germylene ligands comparable to those of NHCs in the major transition metal catalytic processes.
  Wiley, Scientific journal
  DOI：https://doi.org/10.1002/asia.202300968
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  DOI ID：10.1002/asia.202300968, ISSN：1861-4728, eISSN：1861-471X, PubMed ID：38050920, SCOPUS ID：85179925258
• Synthesis of a homoleptic tris(silylene)-palladium(0) complex and a silylyne-bridged tetranuclear palladium cluster　　　　　　　　　　　　　　　
  Jueri Sekiguchi; Yugo Kazama; Akihiko Ishii; Norio Nakata
  Chemical Communications, Volume：59, Number：65, First page：9844, Last page：9847, Jul. 2023
  We report the reactions of an iminophosphonamido-silylene (1) with different palladium complexes. The reaction of 1 with [Pd(PPh3)4] furnished a homoleptic tris(silylene)-palladium(0) complex. In contrast, treatment of 1 with [PdMe2(tmeda)] led to the unprecedented formation of a non-planar μ3-silylyne-bridged tetranuclear palladium cluster that contains palladium atoms in different oxidation states.
  Scientific journal
  DOI：https://doi.org/10.1039/d3cc02543h
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  DOI ID：10.1039/d3cc02543h, ISSN：1359-7345, eISSN：1364-548X, PubMed ID：37475571, SCOPUS ID：85167346859
• Germylenes　　　　　　　　　　　　　　　
  Norio Nakata
  Organogermanium Compounds: Theory, Experiment, and Applications, 2 Volumes, Volume：1-2, First page：387, Last page：433, Mar. 2023
  This chapter provides a summary of the recent progress accomplished in the area of stable germylenes and their derivatives, mainly those reported in the last decade, including their preparation, spectroscopic characterization, and selected examples of their reactivity. The main part of the chapter is organized according to the stabilization modes exhibited by isolable germylenes, which can be categorized as (I) dialkylgermylenes, (II) diarylgermylenes, (III) N-heterocyclic germylenes, (IV) germylenes stabilized by intramolecular coordination, and (V) germylenes that bear heteroleptic substituents. As coordination chemistry of germylenes, the synthesis, reactivity, and catalytic application of transition metal complexes with the amidinatogermylene ligands will be reviewed in the chapter. Chemical properties of the germylene-transition metal complexes having Ge=M double bonds will be also discussed in this chapter.
  In book
  DOI：https://doi.org/10.1002/9781119613466.ch9
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  DOI ID：10.1002/9781119613466.ch9, SCOPUS ID：85161235287
• Niobium Complexes Supported by Chalcogen-Bridged [OEO]-Type Bis(phenolate) Ligands (E = S, Se): Synthesis, Characterization, and Phenylacetylene Polymerization　　　　　　　　　　　　　　　
  Jing An; Akihiko Ishii; Norio Nakata
  Molecules, Volume：28, Number：6, Mar. 2023
  Trichloro niobium(V) complexes 3 and 4 with the sulfur- or selenium-bridged [OEO]-type bis(phenolate) ligands (E = S, Se) were synthesized and fully characterized on the basis of their NMR spectroscopic data and X-ray crystallographic analysis. In the crystalline state of 4, the [OSeO]-core of the ligand was coordinated to the niobium center in a fac-fashion. The corresponding tribenzyl niobium(V) complexes 5 and 6 were also prepared by the reactions of 3 and 4 with 3 equivalents of PhCH2MgCl in toluene. The X-ray diffraction analysis of 6 revealed that the distorted six-coordinated niobium center incorporated in the [OSeO]-type ligand took a mer-fashion, and one benzyl ligand was coordinated to the niobium center by η2-fashion. Complexes 5 and 6 were tested for the phenylacetylene polymerization that produced poly(phenylacetylene)s (PPAs), oligomers, and triphenylbenzenes (TPBs) depending on the chalcogen atom in the [OEO]-type ligand.
  Scientific journal
  DOI：https://doi.org/10.3390/molecules28062573
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  DOI ID：10.3390/molecules28062573, eISSN：1420-3049, ORCID：130997632, PubMed ID：36985545, SCOPUS ID：85151111380
• 2-[2,6-Diisopropylphenyl]-4-phenyl-5H-5,9b[1′,2′]-benzonaphtho[1,2-b]pyrrol-2-ium Tetrafluoroborate
  Masaru Tanaka; Shota Kamiyama; Akihiko Ishii; Norio Nakata
  Molbank, Volume：2023, Number：1, Mar. 2023
  A novel α,β-unsaturated iminium salt (3) incorporated into a rigid dibenzobarrelene backbone was synthesized by heating N-(anthracen-9-ylmethyl)-2,6-diisopropylaniline (2) and 3-phenyl-2-propynal in THF in the presence of excess amounts of magnesium sulfate and 0.5 equivalents of an HBF4-Et2O complex. The molecular structure of 3 was characterized unambiguously by NMR spectroscopy and single-crystal X-ray diffraction (SCXRD) analyses. Compound 3 exhibits yellow luminescence in CH2Cl2 (λem = 516 nm) and in the solid state (λem = 517 nm) with relatively high to moderate quantum yields (ΦF(CH2Cl2) = 0.63; ΦF(solid) = 0.34).
  Scientific journal
  DOI：https://doi.org/10.3390/M1601
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  DOI ID：10.3390/M1601, eISSN：1422-8599, ORCID：130839900, SCOPUS ID：85152001829
• Iminophosphonamido-Supported Plumbylenes and Plumbyliumylidenes: Synthesis and Properties　　　　　　　　　　　　　　　
  Kazuki Nakaya; Shintaro Takahashi; Akihiko Ishii; Norio Nakata
  Inorganic Chemistry, Volume：61, Number：39, First page：15510, Last page：15519, Sep. 2022
  A series of low-valent lead(II) species, i.e., plumbylenes and plumbyliumylidenes supported by an N,N′-di-tert-butyliminophosphonamide ligand, have been synthesized. Chloroplumbylene [Ph2P(NtBu)2PbCl] (1) was readily prepared by the reaction of the corresponding lithium iminophosphonamide and PbCl2in THF. The substitution reaction of 1 with KN(SiMe3)2in THF afforded the corresponding aminoplumbylene [Ph2P(NtBu)2PbN(SiMe3)2] (2) in the form of colorless crystals. The structures of these plumbylenes in the solid state and in solution were exhaustively characterized using multinuclear NMR spectroscopy and X-ray diffraction analysis. In the crystalline state, 1 adopts a nearly linear polymeric structure in the direction of the c axis via Pb-Cl bonds, with alternating four-membered PbN2P rings. The chloride-abstraction reaction of 1 using Na[B(C6F5)4] in fluorobenzene proceeded efficiently at ambient temperature to furnish plumbyliumylidene [Ph2P(NtBu)2Pb:]+(3+), which was isolated as the air-sensitive yellow borate salt 3[B(C6F5)4]. Plumbyliumylidene 3[B(C6F5)4] acts as a Lewis acid catalyst for the hydroboration of benzophenone and benzaldehyde at catalyst loadings of as low as 0.1 mol % under ambient conditions. Furthermore, the details of the reaction mechanism are discussed on the basis of the results of DFT calculations.
  American Chemical Society (ACS), Scientific journal
  DOI：https://doi.org/10.1021/acs.inorgchem.2c02209
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  DOI ID：10.1021/acs.inorgchem.2c02209, ISSN：0020-1669, eISSN：1520-510X, PubMed ID：36129289, SCOPUS ID：85138895543
• [N,N′-Di-tert-butyl-P,P-diphenylphosphinimidic Amidato-κN,κN′]chlorosilicon-κSi-tetracarbonyliron
  Shintaro Takahashi; Kazuki Nakaya; Akihiko Ishii; Norio Nakata
  Molbank, Volume：2022, Number：3, First page：M1433, Last page：M1433, Aug. 2022
  The title complex {[Ph2P(tBuN)2](Cl)Si:->Fe(CO)4} (2) was synthesized via the reaction of chlorosilylene [Ph2P(tBuN)2]SiCl (1), supported by an iminophosphonamide ligand with Fe(CO)5 in THF. The molecular structure of 2 was fully characterized by NMR (1H, 13C, 29Si, and 31P) and IR spectroscopies, as well as single-crystal X-ray diffraction (SCXRD) analysis. In the SCXRD analysis of 2, the silylene ligand was located in the axial positions of the coordination sphere of the central iron atom and other sites were occupied by carbonyl ligands.
  MDPI AG, Scientific journal
  DOI：https://doi.org/10.3390/m1433
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  DOI ID：10.3390/m1433, eISSN：1422-8599, SCOPUS ID：85138606174
• Effective incorporation of divinylbenzene in the isospecific styrene polymerization catalyzed by an aryl-substituted [OSSO]-type zirconium(IV) complex　　　　　　　　　　　　　　　
  Kazuaki Nakamura; Takuya Kishi; Akihiko Ishii; Norio Nakata
  POLYMER JOURNAL, Volume：54, Number：9, First page：1133, Last page：1137, Jun. 2022
  The abundant incorporation of p-divinylbenzene (DVB) in isotactic poly(styrene) units has been achieved by the stereospecific copolymerization employing an aryl-substituted [OSSO]-type zirconium(IV) precatalyst 2b in the presence of dried modified-methylaluminoxane (dMMAO) as an activator. The resulting poly(iso-styrene-co-DVB)s possessed very high molecular weights (M-W = 93,000-131,000 g mol(-1)) and unimodal polydispersity indices (PDI = 1.8-2.5). The corresponding activities were recorded to reach up to 738 g mmol(2b)(-1)h(-1). The DVB contents (7-20 mol %) in the copolymer could be varied depending upon the feed concentration. These copolymers exhibited an amorphous phase structure with glass transition temperatures (T-g values) of 84.8-110.9 degrees C.
  SPRINGERNATURE, English, Scientific journal
  DOI：https://doi.org/10.1038/541428-022-00660-w
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  DOI ID：10.1038/541428-022-00660-w, ISSN：0032-3896, eISSN：1349-0540, SCOPUS ID：85131416492, Web of Science ID：WOS:000804516800001
• Halogen-Exchange Reactions of Iminophosphonamido-Chlorosilylenes with Alkali Halides: Convenient Synthesis of Heavier Halosilylenes.　　　　　　　　　　　　　　　
  Shintaro Takahashi; Jueri Sekiguchi; Kazuki Nakaya; Akihiko Ishii; Norio Nakata
  Inorganic chemistry, Volume：61, Number：19, First page：7266, Last page：7273, May 2022, ［International magazine］
  Halogen-substituted silylenes are an important building block for synthesizing silicon-based low-valent and multiple-bond species. However, the number of reports on heavier halosilylenes that contain bromine and iodine is still limited. Here, we present a convenient synthesis for bromo- and iodosilylenes supported by an iminophosphonamide ligand. The heavier halosilylenes [Ph2P(tBuN)2]SiX (2: X = Br, 3: X = I) were successfully synthesized via the halogen-exchange reaction of chlorosilylene 1 with alkali halides in THF. As a demonstration of the reactivity of 2 and 3, oxidative addition reactions of 2 and 3 with elemental selenium in C6D6 afforded the corresponding bromo- (5) or iodosilylene-selone (6) as colorless crystals. The molecular structures of 2, 3, 5, and 6 were fully characterized by spectroscopic means and single-crystal X-ray diffraction analysis. Furthermore, the effects of the halogen atom on the electronic state of halosilylenes 1-3 and halosilylene-selones 4-6 were investigated using density functional theory (DFT) calculations.
  English, Scientific journal
  DOI：https://doi.org/10.1021/acs.inorgchem.1c03869
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  DOI ID：10.1021/acs.inorgchem.1c03869, ISSN：0020-1669, eISSN：1520-510X, PubMed ID：35512183, SCOPUS ID：85130042210
• Formation, Chemical and Optical Properties of 1,2,5-Triphenylpentadienyl Cation Fixed in a Rigid Dibenzobarrelene Skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Ryota Ebina; Norio Nakata
  EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Volume：2022, Number：14, Apr. 2022
  1,2,5-Triphenylpentadienyl cation fused with a dibenzobarrelene skeleton was synthesized. The pentadienyl cation was persistent in the solution and characterized by H-1 and C-13 NMR spectroscopies. The cation abstracts a hydride from Et2O at the 5-position to give the 5-H derivative together with acetaldehyde and ethene. The reaction with H2O provided the 5-OH derivative and not the 1-OH precursor. The hydride reduction of the pentadienyl cation with silanes or NaBH4 occurred at the 3- and 5-positions, and the ratio was dependent on the bulkiness of reducing reagents. The cation in dichloromethane exhibited long-wavelength absorptions at 678, 523, and 443 nm and an emission maximum at 729 nm with the emission quantum yield of 0.175, which are longer and larger than those of the referenced 1,5-diphenylpentadienyl cation. TD-DFT calculations show that the absorptions are due to the pi-pi* excitations on 1,2,5-triphenylpentadienyl and dibenzobarrelene benzene rings.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/ejoc.202200033
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  DOI ID：10.1002/ejoc.202200033, ISSN：1434-193X, eISSN：1099-0690, SCOPUS ID：85128078779, Web of Science ID：WOS:000780760700001
• Aluminum(III) di- and monochlorides incorporating an N,N '-chelating iminophosphonamide ligand: synthesis and structures　　　　　　　　　　　　　　　
  Kazuki Nakaya; Akihiko Ishii; Norio Nakata
  MENDELEEV COMMUNICATIONS, Volume：32, Number：1, First page：71, Last page：73, Jan. 2022
  Treatment of lithium iminophosphonamide with AlCl3 in Et2O led to the formation of an aluminum(III) dichloride complex as colorless crystals. The substitution reactions of aluminum(III) dichloride stabilized by an iminophosphonamide ligand with N- and Fe-nucleophiles gave the corresponding compounds of aluminum(III) monochloride. The reaction of the aluminum(HI) dichloride complex with CpNa proceeded slowly at room temperature to form an aluminum(III) monochloride complex bearing an eta(1)(sigma)-bonded cyclopentadienyl ring.
  ELSEVIER, English, Scientific journal
  DOI：https://doi.org/10.1016/j.mencom.2022.01.023
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  DOI ID：10.1016/j.mencom.2022.01.023, ISSN：0959-9436, eISSN：1364-551X, SCOPUS ID：85125602303, Web of Science ID：WOS:000766626200023
• Hydroboration of carbonyls and imines by an iminophosphonamido tin(II) precatalyst.　　　　　　　　　　　　　　　
  Kazuki Nakaya; Shintaro Takahashi; Akihiko Ishii; Kajjana Boonpalit; Panida Surawatanawong; Norio Nakata
  Dalton transactions (Cambridge, England : 2003), Volume：50, Number：41, First page：14810, Last page：14819, Oct. 2021, ［International magazine］
  A novel three-coordinated tin(II) chloride [Ph2P(NtBu)2]SnCl (1) supported by an N,N'-di-tert-butyliminophosphonamide having two phenyl groups on the phosphorus atom was synthesized by the reaction of the starting lithium iminophosphonamide [Ph2P(NtBu)2]Li with SnCl2·(dioxane) in toluene. The molecular structure of 1 was established by X-ray diffraction analysis. Tin(II) chloride 1 can act as an efficient precatalyst for the hydroboration of a wide variety of aldehydes, ketones, and imines at -10 °C. DFT calculations propose that hydroboration involves hydride transfer from the corresponding tin(II) hydride intermediate [Ph2P(NtBu)2]SnH (10) to the carbonyl substrates via four-membered transition states (TS-12), affording three-coordinated tin(II) alkoxide intermediates [Ph2P(NtBu)2]SnOR (13), followed by the stepwise reaction of 13 with HBpin (pin = pinacolate) to release the boronate esters and regenerate the tin(II) hydride 10. The stoichiometric reaction of the in site-generated 10 with benzophenone 2a at -10 °C led to the formation of 13. Moreover, 13 also stoichiometrically reacted with HBpin at -10 °C, forming the corresponding boronate ester 3a and 10 based on the 1H NMR spectrum of the reaction mixture.
  English, Scientific journal
  DOI：https://doi.org/10.1039/d1dt01856f
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  DOI ID：10.1039/d1dt01856f, ISSN：1477-9226, eISSN：1477-9234, PubMed ID：34596191, SCOPUS ID：85118226328
• Strained and Reactive Donor/Acceptor-Supported Metallasilanone　　　　　　　　　　　　　　　
  Shintaro Takahashi; Manuel A. Ramos-Enríquez; Ekaterina Bellan; Antoine Baceiredo; Nathalie Saffon-Merceron; Norio Nakata; Daisuke Hashizume; Vicenç Branchadell; Tsuyoshi Kato
  Angewandte Chemie - International Edition, Volume：60, Number：34, First page：18489, Last page：18493, Aug. 2021
  A novel stable donor/acceptor-supported MnI-metallasilanone 3 was synthesized. The intramolecular silanone-MnI interaction induces a highly strained three-membered cyclic structure, leading to an exceptionally high reactivity of 3 as a donor/acceptor complex of silanone. Indeed, metallasilanone 3 readily reacts with various small molecules such as H2 or ethylene gas in mild conditions.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.202105526
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  DOI ID：10.1002/anie.202105526, ISSN：1433-7851, eISSN：1521-3773, PubMed ID：34159706, SCOPUS ID：85109931156
• Formation of silaimines from a sterically demanding iminophosphonamido chlorosilyleneviaintramolecular N-P bond cleavage　　　　　　　　　　　　　　　
  Shintaro Takahashi; Akihiko Ishii; Norio Nakata
  Chemical Communications, Volume：57, Number：55, First page：6728, Last page：6731, Jul. 2021
  The sterically demanding iminophosphonamido chlorosilylene [Ph2P(DipN)2]SiCl (Dip = 2,6-diisopropylphenyl) was synthesized and fully characterized using NMR spectroscopy and X-ray crystallography. Substitution reactions of [Ph2P(DipN)2]SiCl with N- and Fe-nucleophiles led to the unexpected formation of the corresponding silaimine derivatives. This process involves the ring-opening rearrangement of three-coordinated silylene intermediates that proceedsviaintramolecular N-P bond cleavage.
  Scientific journal
  DOI：https://doi.org/10.1039/d1cc02812j
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  DOI ID：10.1039/d1cc02812j, ISSN：1359-7345, eISSN：1364-548X, PubMed ID：34159981, SCOPUS ID：85109419079
• Interconversion between a silaimine and an aminosilylene supported by an iminophosphonamide ligand　　　　　　　　　　　　　　　
  Shintaro Takahashi; Akihiko Ishii; Norio Nakata
  Chemical Communications, Volume：57, Number：26, First page：3203, Last page：3206, Apr. 2021
  The reaction of a chlorosilylene, supported by an iminophosphonamide ligand, with KN(SiMe3)2resulted in the formation of a silaimine instead of the expected aminosilylene. However, this silaimine exists in equilibrium with the corresponding aminosilylene, which was experimentally demonstrated using variable-temperature NMR spectroscopy and a trapping reaction with elemental selenium to give a silaselenourea.
  Scientific journal
  DOI：https://doi.org/10.1039/d1cc00667c
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  DOI ID：10.1039/d1cc00667c, ISSN：1359-7345, eISSN：1364-548X, PubMed ID：33687409, SCOPUS ID：85103473238
• An Iminophosphonamido-Chlorosilylene as a Strong σ-Donating NHSi Ligand: Synthesis and Coordination Chemistry　　　　　　　　　　　　　　　
  Shintaro Takahashi; Jueri Sekiguchi; Akihiko Ishii; Norio Nakata
  Angewandte Chemie - International Edition, Volume：60, Number：8, First page：4055, Last page：4059, Feb. 2021
  The N-heterocyclic silylene (NHSi) [Ph2P(tBuN)2]SiCl (1), supported by an iminophosphonamide ligand, was obtained from the dehydrochlorination of [Ph2P(tBuN)2]SiHCl2 (2) with LiN(SiMe3)2. NHSi 1 contains an extremely high-energy HOMO level and consequently displays unique coordination behavior toward RhI complexes. When 1 was treated with 1/4 of an equivalent of [RhCl(cod)]2 (cod=1,5-cyclooctadiene), the 14-electron Y-shaped bis(chlorosilylene) RhI complex 5 was obtained as dark purple crystals. The reaction of 1 with 1/6 of an equivalent of [RhCl(cod)]2 yielded the cationic tris(silylene)-RhI complex [6]+⋅Cl− as red crystals, wherein a two-coordinated silylene ligand engages in a Si=Rh double bond. A structural analysis of 5 and [6]+⋅Cl− revealed that the central rhodium atoms adopt trigonal and square-planar coordination geometries, respectively, with considerably shortened Si-Rh bonds [5: 2.1605(5) Å; [6]+: 2.133(1) Å].
  Scientific journal
  DOI：https://doi.org/10.1002/anie.202013622
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  DOI ID：10.1002/anie.202013622, ISSN：1433-7851, eISSN：1521-3773, PubMed ID：33105520, SCOPUS ID：85097828314
• Synthesis and Properties of 1-(Dialkylstannyl)-1,4-diphenyl-1,3-butadiene Fused with a Dibenzobarrelene and the Corresponding Pentaorganostannate　　　　　　　　　　　　　　　
  Yasuha Miyashita; Norio Nakata; Akihiko Ishii
  Zeitschrift fur Anorganische und Allgemeine Chemie, Volume：647, Number：19, First page：1883, Last page：1889, 2021
  1-(Dialkylstannyl)-1,4-diphenyl-1,3-butadiene derivatives that fuse with a dibenzobarrelene were synthesized by the reaction of the dilithium salt, prepared by the treatment of the corresponding tellurium analogue with BuLi, with R2SnCl2 (R=Me or Bu). When Me2SnCl2 was used, a Me−Bu exchange (Bu is from BuLi) was observed. The dimethyl-, butylmethyl-, and dibutylstannyl derivatives exhibit weak fluorescence in solution and the solid state. The dibutylstannyl derivative reacted with BuLi in THF to give a pentaorganostannate, which was characterized by means of 119Sn NMR and UV-vis spectroscopies. Their optical properties were analyzed with TD-DFT calculations. The first excitation of dialkylstannyl derivatives is assigned to the π-π* excitation, and an intersystem crossing from the relaxed S1 state to a triplet state was suggested. The calculations show that the dark red color of the pentaorganostannate is ascribed to the excitation from the hypervalent Sn−C bonds (σ) to the π* orbital of the 1,4-diphenyl-1,3-butadiene moiety.
  Scientific journal
  DOI：https://doi.org/10.1002/zaac.202100227
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  DOI ID：10.1002/zaac.202100227, ISSN：0044-2313, eISSN：1521-3749, SCOPUS ID：85113649361
• Synthesis of a Stable N-Hetero-Rh^I-Metallacyclic Silanone　　　　　　　　　　　　　　　
  Shintaro Takahashi; Kazuki Nakaya; María Frutos; Antoine Baceiredo; Nathalie Saffon-Merceron; Stéphane Massou; Norio Nakata; Daisuke Hashizume; Vicenç Branchadell; Tsuyoshi Kato
  Angewandte Chemie - International Edition, Volume：59, Number：37, First page：15937, Last page：15941, Sep. 2020
  A novel N-hetero-RhI-metallacyclic silanone 2 has been synthesized. The silanone 2, showing an extremely large dimerization energy (ΔG=+86.2 kcal mol−1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular Csp3−H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5. The exceptional stability of 2, related to the unusual electronic and steric effects of RhI-substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H2 starts with the hydrogenation of RhI center leading to the corresponding RhIII-dihydride complex 7 and it undergoes a cis/trans-isomerization via a particular mechanism, demonstrating that addition-elimination processes can also happen for silanones just like for their carbon analogues!.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.202006088
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  DOI ID：10.1002/anie.202006088, ISSN：1433-7851, eISSN：1521-3773, PubMed ID：32495454, SCOPUS ID：85087618382
• Synthesis and photophysical properties of conjugated thioketone, thioketone S-oxide (Sulfine), and related compounds incorporated in a dibenzobarrelene skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Ryota Ebina; Mari Shibata; Yuki Hayashi; Norio Nakata
  Journal of Sulfur Chemistry, Volume：41, Number：3, First page：238, Last page：257, May 2020
  Conjugated thioketone and thioketone S-oxide (sulfine) were synthesized from the corresponding ketone conjugated to a 1,3-butadiene system incorporated in a dibenzobarrelene skeleton. The conjugated thioketone was obtained by the reaction of the corresponding diazo compound with elemental sulfur, the oxidation of which with m-chloroperoxybenzoic acid provided the conjugated sulfine as a mixture of (Z)- and (E)-stereoisomers. (E)-Sulfine gradually isomerized to (Z)-sulfine in solution in the dark. Photoisomerization between (Z)- and (E)-sulfines was observed under photoirradiation together with the desulfurization to the corresponding ketone. The conjugated thioketone showed the weak long-wavelength absorption at 626 nm due to the n-π* excitation in the optical absorption spectrum and nonphotoluminescent. The conjugated (Z)-sulfine exhibited the long-wavelength absorption at 448 nm due to the π-π* excitation and very weak photoluminescence at 489 nm with the quantum yield of 0.002 at room temperature. The weak photoluminescence was enhanced in EtOH at 77 K showing yellow luminescence, and the quantum yield increased to 0.32. Lifetime values of the luminescence (2.4 and 6.8 ns) at 77 K suggests that the luminescence is fluorescence. A large solvent effect and a similar temperature dependency of photoluminescence were observed for the conjugated ketone.
  Scientific journal
  DOI：https://doi.org/10.1080/17415993.2020.1727905
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  DOI ID：10.1080/17415993.2020.1727905, ISSN：1741-5993, eISSN：1741-6000, SCOPUS ID：85084272782
• Synthesis, Structure, and Dynamic Behavior of Hydrido(dihydrosilyl) Platinum(II) Complex Having Me3P Ligands　　　　　　　　　　　　　　　
  Norio Nakata; Motoo Aoyama; Shintaro Takahashi; Nanami Kato; Akihiko Ishii
  Chemistry Letters, Volume：49, Number：9, First page：1043, Last page：1046, 2020
  A hydrido(dihydrosilyl) platinum(II) complex having PMe3 ligands, [cis-PtH(SiH2Trip)(PMe3)2] (2) (Trip = 9-triptycyl) was prepared by the ligand-exchange reaction of [PtH(SiH2Trip)(PMe3)(PPh3)] (1) with an excess amount of free PMe3 in hexane. X-ray crystallographic analysis of 2 revealed that the platinum center adopts a twisted square-planar geometry; the dihedral angle between the PPtP and SiPtH planes is 10.43°. The complex displayed a fluxional NMR behavior in solution on the NMR time scale, where a ©1-SiH structure was suggested as a transition state of the rate-controlling step by DFT calculation.
  Scientific journal
  DOI：https://doi.org/10.1246/CL.200356
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  DOI ID：10.1246/CL.200356, ISSN：0366-7022, eISSN：1348-0715, SCOPUS ID：85090915033
• 1-phosphino-1,3-butadiene derivatives incorporated with dibenzobarrelene skeleton: Synthesis and photophysical properties　　　　　　　　　　　　　　　
  Akihiko Ishii; Chiharu Kikushima; Yuki Hayashi; Nobuhiko Ohtsuka; Norio Nakata; Atsuya Muranaka; Yusuke Tanaka; Masanobu Uchiyama
  Bulletin of the Chemical Society of Japan, Volume：93, Number：12, First page：1430, Last page：1442, 2020
  An intramolecular [4+2] cycloaddition of 1-(9-anthrylchloro-phosphino)-1,4-diphenylbut-1-en-3-yne produced the 1-(chloro-phosphino)-1,4-diphenyl-1,3-butadiene derivative incorporated with a dibenzobarrelene skeleton, the following reactions of which gave the corresponding secondary phosphine oxide and phenylphosphine sulfide. The secondary phosphine oxide was deprotonated with butyllithium followed by treatment with methyl iodide to give methylphosphine oxide. The phenylphosphine sulfide was desulfurized with P(NMe2)3 to give the corresponding phenylphosphine, which was converted to the oxide and selenide and AuCl and BH3 complexes. Their structures were determined by X-ray crystallography. These compounds show blue fluorescence in solution (¯F = 0.490.86) and the solid state (¯F = 0.020.72) in a narrow range (em = 442463 nm) except the phenylphosphine selenide with a low fluorescence efficiency. Their photophysical properties were considered theoretically. The secondary phosphine oxide and the methylphosphine oxide were optically resolved by means of HPLC equipped with a chiral column, and the chiroptical properties were investigated to show weak circular polarized luminescence (CPL) of «gem« = 2.88.8 © 1014.
  Scientific journal
  DOI：https://doi.org/10.1246/BCSJ.20200190
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  DOI ID：10.1246/BCSJ.20200190, ISSN：0009-2673, eISSN：1348-0634, SCOPUS ID：85097993812
• A Stable N-Hetero-Rh-Metallacyclic Silylene　　　　　　　　　　　　　　　
  Shintaro Takahashi; Ekaterina Bellan; Antoine Baceiredo; Nathalie Saffon-Merceron; Stéphane Massou; Norio Nakata; Daisuke Hashizume; Vicenç Branchadell; Tsuyoshi Kato
  Angewandte Chemie - International Edition, Volume：58, Number：30, First page：10310, Last page：10314, Jul. 2019
  A cyclic (amino)metal-substituted dicoordinated silylene derivative has been synthesized and fully characterized. Of particular interest is that the N-hetero-RhI-metallacyclic silylene exhibits a distorted tetrahedral geometry around the rhodium atom and a considerably shortened Si−Rh bond (2.138 Å) compared to classical Si−Rh single bonds (ca. 2.30–2.35 Å). A theoretical investigation reveals that the geometrical deviation around the rhodium center from the classical square-planar to a tetrahedral geometry increases the π-donating and σ-accepting character of the rhodium atom, thereby efficiently stabilizing the silylene moiety.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.201904594
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  DOI ID：10.1002/anie.201904594, ISSN：1433-7851, eISSN：1521-3773, PubMed ID：31132319, SCOPUS ID：85068172718
• Carbazolyl-substituted [OSSO]-type zirconium(IV) complex as a precatalyst for the oligomerization and polymerization of α-olefins　　　　　　　　　　　　　　　
  Norio Nakata; Kazuaki Nakamura; Shotaro Nagaoka; Akihiko Ishii
  Catalysts, Volume：9, Number：6, Jun. 2019
  The dibenzyl zirconium(IV) complex (4) incorporating with a carbazolyl(Cbz)-substituted [OSSO]-type bis(phenolate) ligand was synthesized. Upon activation with dried modified methylaluminoxane (dMMAO), precatalyst 4 at relatively low catalyst loadings was found to promote the 1,2-regioselective oligomerization of 1-hexene to produce the corresponding vinylidene-ended oligomers with moderate turnover frequencies (TOFs) up to 2080 h−1. The13 C NMR analysis of the resulting oligomers revealed the formation of dimer-enriched oligo(1-hexene)s in 39–62% distributions. The precatalyst 4 with dried methylaluminoxane (dMAO) also exhibited good performance in the polymerization of styrene yielding isotactic polystyrenes ([mm] > 99%) with quite large molecular weights (Mw < 508,100 g mol−1) and relatively high catalytic activity (up to 2810 g mmol(4)−1 h−1).
  Scientific journal
  DOI：https://doi.org/10.3390/catal9060528
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  DOI ID：10.3390/catal9060528, eISSN：2073-4344, SCOPUS ID：85069943944
• Dicationic ditelluride salts stabilized by N-heterocyclic carbene　　　　　　　　　　　　　　　
  Norio Nakata; Fumihiko Kawauchi; Shintaro Takahashi; Akihiko Ishii
  New Journal of Chemistry, Volume：43, Number：27, First page：10894, Last page：10898, 2019
  Treatment of 1,3-bis(2,6-diisopropylphenyl)imidazoline-2-tellone 1 with Tf2O in CH2Cl2 resulted in the formation of dicationic ditelluride salt 22+ 2 (OTf)- as air-stable green crystals in 88% yield. The anion exchange reaction of 22+ 2 (OTf)- with Na[B(C6F5)4] proceeded in CH3CN at room temperature giving the corresponding borate salt 22+ 2 [B(C6F5)4]- as blue crystals in 40% yield. The structures of these dicationic ditelluride derivatives were fully characterized on the basis of their NMR spectroscopic data and X-ray crystallography. In the crystalline state of 22+ 2 (OTf)-, two NHC ligands are entirely perpendicular to the central Te-Te bond with a Te-Te-C-N torsion angle of 89.93(19)°. In sharp contrast, X-ray analysis of 22+ 2 [B(C6F5)4]- revealed that two NHC ligands and the central Te-Te moiety are essentially coplanar with a Te-Te-C-N torsion angle of 7.99(17)°. In the DFT calculation for the model compound 32+, NBO orbitals around the Te-Te moiety in Ci symmetry consist of a Te-Te σ-bonding orbital, a Te-C σ-bonding orbital, a lone pair orbital on the Te atom (mainly s-character), and a lone pair orbital on the Te atom (pure p-character).
  Scientific journal
  DOI：https://doi.org/10.1039/c9nj02138h
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  DOI ID：10.1039/c9nj02138h, ISSN：1144-0546, eISSN：1369-9261, SCOPUS ID：85068593357
• A reversible and turn-on type fluorescence behaviour of hydrogen sulfide via a redox cycle between selenoxide and selenide　　　　　　　　　　　　　　　
  Tatsuro Annaka; Norio Nakata; Akihiko Ishii
  New Journal of Chemistry, Volume：43, Number：29, First page：11643, Last page：11652, 2019
  A turn-on type fluorescence behaviour of H2S based on a reversible selenoxide/selenide redox system is reported. Very weakly fluorescent selenoxides of 1,4-diphenyl-1-seleno-1,3-butadiene derivatives, incorporated with dibenzobarrelene (Dbb)- or (mono)benzobarrelene (Mbb) (DbbSeO and MbbSeO, respectively), are reduced quickly with NaSH as the equivalent of H2S in a dilute solution of CH3CN/PBS at pH 7.4 to yield the respective intensely fluorescent selenides (DbbSe and MbbSe). The selenoxides are highly selective for H2S compared to other biothiols such as l-cysteine (Cys) and reduced glutathione (GSH). On the other hand, the intense fluorescence of DbbSe is effectively quenched by oxidation with NaOCl as the equivalent of HOCl. The oxidation also showed high selectivity toward HOCl against other oxidants such as H2O2, t-BuOOH, and ONOO-. This reversibility of the fluorescence behaviour suggests that this system could monitor H2S and HOCl generation in one-pot. The fluorescence properties of DbbSe and DbbSeO were discussed based on the results of TD-DFT calculations.
  Scientific journal
  DOI：https://doi.org/10.1039/c9nj02813g
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  DOI ID：10.1039/c9nj02813g, ISSN：1144-0546, eISSN：1369-9261, SCOPUS ID：85069790999
• Group 13 metal carbochalcogenoato complexes: Synthesis, X-ray structure analysis, and reactions　　　　　　　　　　　　　　　
  Norio Nakata; Shinzi Kato; Osamu Niyomura; Masahiro Ebihara
  Heteroatom Chemistry, Volume：29, Number：5-6, Dec. 2018
  A series of alkali metal tetrakis(carbochalcogenoato)-gallates and -indates M[M′(EOCR)4](solv.) (M = alkali metal; M′ = Ga, In; E = S, Se) and tris(carbodithioato)aluminum, -gallates and -indates M′ (SSCR)3 (M′ = Al, Ga, In) were prepared by the reactions of alkali metal carbochalcogenate with metal trihalogenides (M′X3; M′ = Al, Ga, In; X = Cl, Br) and by those of piperidinium carbodithioates or carbodithioic and carboselenoic acids with M′X3, respectively. An X-ray molecular structure analysis revealed that they have an acetone molecule as a crystal solvent. The reactions of the potassium complexes K[M′ (EOCR)4](H2O) (E = S, Se) with methanol and primary and secondary amines gave the corresponding methyl ester and amides in good yields, while the reactions with iodomethane and iodine gave S- and Se-methyl chalcogenoesters RCOEMe (E = S, Se) in good yields. Similar reactions of the tris(carbodithioato)gallates and -indates led to the corresponding O-methyl thioesters, thioamides, and S-methyl dithioesters in moderate to good yields. Oxidation of the tetrakis- and tris-derivatives with iodine afforded the corresponding diacyl dichalcogenides (RCOE)2 (E = S, Se) and di(carbothioyl) disulfides in quantitative yields. These reactions appeared to occur on the carbonyl or selenium atom of the tetrakis compounds and on the sulfide sulfur or thiocarbonyl carbon atom of the tris-compounds, respectively. A possible mechanism for these I2-oxidation reactions is discussed.
  Scientific journal
  DOI：https://doi.org/10.1002/hc.21445
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  DOI ID：10.1002/hc.21445, ISSN：1042-7163, eISSN：1098-1071, SCOPUS ID：85056349724
• Highly Efficient and 1,2-Regioselective Method for the Oligomerization of 1-Hexene Promoted by Zirconium Precatalysts with [OSSO]-Type Bis(phenolate) Ligands　　　　　　　　　　　　　　　
  Norio Nakata; Kazuaki Nakamura; Akihiko Ishii
  Organometallics, Volume：37, Number：15, First page：2640, Last page：2644, Aug. 2018
  A mixture of zirconium complex 7, which carries a phenyl-substituted [OSSO]-type bis(phenolate) ligand, and dried modified methylaluminoxane (dMMAO) catalyzes the 1,2-regioselective oligomerization of 1-hexene at relatively low catalyst loadings (0.0056 mol %) to produce the corresponding vinylidene-terminated dimer, 5-methyleneundecane (74-80%), and trimer, 7-butyl-5-methylenetridecane (8-11%). The observed turnover frequencies (TOFs) are relatively high (up to 11※100 h-1). When a mixture of 2,6-dimethylphenyl-substituted precatalyst 8 and dMMAO was used, the oligomerization of 1-hexene proceeded effectively to afford predominantly the dimer (87-91%) together with a small amount of the trimer (8-11%) at remarkably high TOFs (up to 6640 h-1).
  Scientific journal
  DOI：https://doi.org/10.1021/acs.organomet.8b00411
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  DOI ID：10.1021/acs.organomet.8b00411, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：85051428985
• Synthesis and Photophysical Properties of Dibenzobarrelene-Incorporated 1,4-Diphenyl-1,3-pentadienes and a 5-Sila Derivative Having High Fluorescence Efficiency　　　　　　　　　　　　　　　
  Akihiko Ishii; Mari Shibata; Ryota Ebina; Norio Nakata
  European Journal of Organic Chemistry, Volume：2018, Number：8, First page：1011, Last page：1018, Feb. 2018
  Two dibenzobarrelene-incorporated 1,3-pentadienes and a 5-sila derivative have been synthesized by intramolecular cycloaddition reactions between (9-anthryl)methyl, (9-anthryl)hydroxymethyl, or (9-anthryl)dimethylsilyl groups and a phenylethynyl group linked by an ethene moiety with a cis conformation. The three compounds exhibit blue luminescence (λem = 432–445 nm) in CH2Cl2 with high quantum yields (ΦF = 0.83–0.92). In the solid state, the methylene and dimethylsilyl derivatives luminesce (λem = 442 and 438 nm, respectively) with narrow full-width at half-maxima (FWHM, 40 and 37 nm, respectively), whereas the hydroxymethylene compound shows a broad and slightly redshifted emission (λem = 488 nm, FWHM = 112 nm) due to intermolecular hydrogen bonding. The fluorescence intensity of the dimethylsilyl compound was decreased by desilylation with Bu4NF. The structures of the compounds were characterized unambiguously by NMR spectroscopy and X-ray crystallography, and their photophysical properties were elucidated both experimentally as well as by TD-DFT calculations.
  Scientific journal
  DOI：https://doi.org/10.1002/ejoc.201701616
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  DOI ID：10.1002/ejoc.201701616, ISSN：1434-193X, eISSN：1099-0690, SCOPUS ID：85042646291
• Chlorogermylenes and -stannylenes stabilized by diimidosulfinate ligands: Synthesis, structures, and reactivity　　　　　　　　　　　　　　　
  Norio Nakata; Narimi Hosoda; Shintaro Takahashi; Akihiko Ishii
  Dalton Transactions, Volume：47, Number：2, First page：481, Last page：490, 2018
  The reaction of the lithium salt of N,N′-di-tert-butyldiimidosulfinate ([PhS(NtBu)2]Li) having a phenyl group on the sulphur atom with ECl2·(dioxane) (E = Ge, Sn) afforded the corresponding chlorogermylene [PhS(NtBu)2]GeCl 1 and -stannylene [PhS(NtBu)2]SnCl 2, respectively. In contrast, treatment of the N,N′-bis(trimethylsilyl)diimidosulfinate ion ([PhS(NSiMe3)2]-) with ECl2·(dioxane) resulted in the unexpected formations of six-membered 1,3-bis(chlorogermylene) [PhS(NSiMe3)2(η1-η1-GeCl)2[μ-NSPh(NHSiMe3)] 7 and -stannylene [PhS(NSiMe3)2(η1-η1-SnCl)2[μ-NSPh(NHSiMe3)] 8. The structures of these chlorometallylene derivatives were fully characterized on the basis of their NMR spectroscopic data and X-ray diffraction. In the crystalline states of 1 and 2, the diimidosulfinate ligands chelate to the metal centre to form slightly hinged four-membered EN2S rings. On the other hand, X-ray analyses of 7 and 8 revealed that the central six-membered E2N3S rings adopt a distorted boat-conformation, and one diimidosulfinate ligand coordinates to the metal centre in a bridging monodentate μ-η1-η1-fashion. As the reactivity of 1 and 2, the oxidation of 1 with elemental chalcogen (S8 or Se) afforded the corresponding tetra-coordinated germanium compounds [PhS(NtBu)2]Ge(Ch)Cl 3 (ChS) and 4 (ChSe). In sharp contrast, the reactions of 2 with elemental chalcogen resulted in the formation of four-membered Sn2Ch2 ring compounds, 1,3,2,4-dichalcogenadistannetanes {(PhS(NtBu)2)SnCl(μ-Ch)}25 (ChS) and 6 (ChSe).
  Scientific journal
  DOI：https://doi.org/10.1039/c7dt04390b
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  DOI ID：10.1039/c7dt04390b, ISSN：1477-9226, eISSN：1477-9234, PubMed ID：29230468, SCOPUS ID：85040198766
• Group 2 metal bis(arenecarbochalcogenoate)(crown ether) complexes: Isolation and structural analysis　　　　　　　　　　　　　　　
  Yoshiharu Tatematsu; Shinzi Kato; Norio Nakata; Masahiro Ebihara; Osamu Niyomura; Koh Sugamata; Mariko Yukimoto; Mao Minoura
  Dalton Transactions, Volume：47, Number：29, First page：9787, Last page：9794, 2018
  A series of Group 2 metal bis(arenecarbochalcogenoato)(crown ether) complexes M(EE′CAr)2(L)(L′)x (M = Mg, Ca, Sr, Ba; Ar = aryl; E = S, Se; E′ = O, S; L = H2O or THF; L′ = 15-crown-5, 18-crown-6) were synthesized and their structures were revealed by X-ray analyses. The two carbothioato ligands in Mg, Ca and Sr 15-crown-5 complexes are located on the same side of the crown ether plane, while those in Mg, Ca, Sr, and Ba 18-crown-6 compounds are on both sides of the 18-crown-6 plane (trans relative to the plane). For the Ca 15-crown-5 complex, both carbothioato ligands are connected to the central Ca ion through an oxygen atom in a monodentate manner, and the two hydrogen atoms of the coordinated water molecule are intramolecularly hydrogen-bonded with thiocarbonyl sulfur atoms. One of the two carbothioate groups in the Ca 18-crown-6 complex is connected in a bidentate manner to the central metal, while the other is connected in a monodentate manner through an oxygen atom. The two thiocarboxylato ligands in the Sr 15-crown-5 congener are connected in a bidentate fashion to the same side of the crown ether plane. The Ca and Sr compounds are the first examples of alkali earth metal carbochalcogenoate complexes in which carbochalcogenolato ligands are connected in a monodentate manner through an oxygen atom. Both chalcogenoato ligands in Ba(SOCC6H4Me-4)2(18-crown-6) and Sr(SeOCC6H4Me-4)2(18-crown-6) are coordinated in a bidentate manner to the central metal ion.
  Scientific journal
  DOI：https://doi.org/10.1039/c8dt01959b
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  DOI ID：10.1039/c8dt01959b, ISSN：1477-9226, eISSN：1477-9234, PubMed ID：29992221, SCOPUS ID：85050877323
• Si-H bond activation of a primary silane with a Pt(0) complex: Synthesis and structures of mononuclear (hydrido)(dihydrosilyl) platinum(II) complexes　　　　　　　　　　　　　　　
  Norio Nakata; Nanami Kato; Noriko Sekizawa; Akihiko Ishii
  Inorganics, Volume：5, Number：4, Dec. 2017
  A hydrido platinum(II) complex with a dihydrosilyl ligand, [cis-PtH(SiH2Trip)(PPh3)2] (2) was prepared by oxidative addition of an overcrowded primary silane, TripSiH3 (1, Trip = 9-triptycyl) with [Pt(η2-C2H4)(PPh3)2] in toluene. The ligand-exchange reactions of complex 2 with free phosphine ligands resulted in the formation of a series of (hydrido)(dihydrosilyl) complexes (3-5). Thus, the replacement of two PPh3 ligands in 2 with a bidentate bis(phosphine) ligand such as DPPF [1,2-bis(diphenylphosphino)ferrocene] or DCPE [1,2-bis(dicyclohexylphosphino)ethane] gave the corresponding complexes [PtH(SiH2Trip)(L-L)] (3: L-L = dppf, 4: L-L = dcpe). In contrast, the ligand-exchange reaction of 2 with an excess amount of PMe3 in toluene quantitatively produced [PtH(SiH2Trip)(PMe3)(PPh3)] (5), where the PMe3 ligand is adopting trans to the hydrido ligand. The structures of complexes 2-5 were fully determined on the basis of their NMR and IR spectra, and elemental analyses. Moreover, the low-temperature X-ray crystallography of 2, 3, and 5 revealed that the platinum center has a distorted square planar environment, which is probably due to the steric requirement of the cis-coordinated phosphine ligands and the bulky 9-triptycyl group on the silicon atom.
  Scientific journal
  DOI：https://doi.org/10.3390/inorganics5040072
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  DOI ID：10.3390/inorganics5040072, eISSN：2304-6740, SCOPUS ID：85045386833
• Zirconium and Hafnium Complexes with Cycloheptane- or Cyclononane-Fused [OSSO]-Type Bis(phenolato) Ligands: Synthesis, Structure, and Highly Active 1-Hexene Polymerization and Ring-Size Effects of Fused Cycloalkanes on the Activity　　　　　　　　　　　　　　　
  Akihiko Ishii; Keita Ikuma; Norio Nakata; Kazuaki Nakamura; Hiroshi Kuribayashi; Kazuo Takaoki
  Organometallics, Volume：36, Number：20, First page：3954, Last page：3966, Oct. 2017
  Zirconium and hafnium complexes bearing cycloheptane- or cyclononane-fused [OSSO]-type bis(phenolato) ligands ([C7] and [C9], respectively) were prepared and subjected to the polymerization of 1-hexene as the precatalyst. The polymerizations produced poly(1-hexene)s with high activities and high isospecificity, where complexes bearing [C9] were more reactive than those bearing [C7]. Their activities were compared with those of the corresponding complexes bearing cyclohexane- and cyclooctane-fused ligands ([C6] and [C8], respectively), which we reported previously, to show the order of activity [C8] > [C9] > [C7] > [C6]. The ring-size effect on the activity was investigated with the help of DFT calculations on active and dormant cationic zirconium species, π complexes of the active species with propene, and transition states for propene insertion into the Zr-C(iBu) bond. The order of activity speculated from the activation energy, that is the energy difference between the π complex and the corresponding transition state, was [C8] > [C7] > [C9] ≈ [C6]. However, calculations on active and dormant cationic zirconium complexes including [B(C6F5)4]- as the counteranion revealed that the active species are more stable than the dormant species by 9.1 kcal mol-1 for [C8] followed by 7.4 kcal mol-1 for [C9] and 3.1 kcal mol-1 for [C7] and, in contrast, that the active species with [C6] is less stable by 1.0 kcal mol-1 than the corresponding dormant species. Thus, the abundances of active species bearing [C6] and [C7] are reduced, which leads to the reversal of the order of [C7] and [C9] on the basis of activation energy to reproduce the order observed experimentally.
  Scientific journal
  DOI：https://doi.org/10.1021/acs.organomet.7b00586
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  DOI ID：10.1021/acs.organomet.7b00586, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：85032011082
• Donor-Stabilized Silylene/Phosphine-Supported Carbon(0) Center with High Electron Density　　　　　　　　　　　　　　　
  Thibault Troadec; Tatsuya Wasano; Romaric Lenk; Antoine Baceiredo; Nathalie Saffon-Merceron; Daisuke Hashizume; Yosuke Saito; Norio Nakata; Vicenç Branchadell; Tsuyoshi Kato
  Angewandte Chemie - International Edition, Volume：56, Number：24, First page：6891, Last page：6895, Jun. 2017
  An isolable donor-stabilized silavinylidene phosphorane was synthesized. This molecule, which can also be regarded as a new carbon(0) complex featuring a phosphine and a donor-stabilized silylene ligand, presents a central carbon atom with a remarkably high electron density (−1.82). Furthermore, the experimental electron-density study of this compound demonstrates the delocalization of the σ-lone pair at the central carbon atom toward the silicon center, a feature which is remarkably different from electronic situation of other bent-allene-type molecules. This result clearly demonstrates the powerful electron-donating ability of donor-stabilized silylene ligands, as well as their excellent electron-acceptor properties.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.201702858
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  DOI ID：10.1002/anie.201702858, ISSN：1433-7851, eISSN：1521-3773, PubMed ID：28474846, SCOPUS ID：85018387081
• Enantio- and Stereoselective Cyclopolymerization of Hexa-1,5-diene Catalyzed by Zirconium Complexes Possessing Optically Active Bis(phenolato) Ligands　　　　　　　　　　　　　　　
  Norio Nakata; Takanori Watanabe; Tomoyuki Toda; Akihiko Ishii
  Macromolecular Rapid Communications, Volume：37, Number：22, First page：1820, Last page：1824, Nov. 2016
  Enantio- and stereoselective cyclopolymerization of hexa-1,5-diene was achieved by enantiomerically pure dichloro zirconium(IV) pre-catalysts 2 possessing chiral [OSSO]-type bis(phenolate) ligands (−)-1 and (+)-1 in combination with dried methylaluminoxane (dMAO) as an activator. The corresponding activities were recorded with quite high values up to 1,960 g mmol(2)–1 h–1, which are extremely larger than those of the related complexes. The microstructure analysis for the PMCPs furnished by pre-catalysts (Λ,S,S)-2 and (Δ,R,R)-2 showed good isotacticity factors (α = 75−78%) and relatively high proportions of trans-cyclopentane rings (σ = 14−21%). These enantiomeric PMCPs exhibited large specific optical rotations ([α]D = +28 to +32° from (Λ,S,S)-2, −26 to −34° from (Δ,R,R)-2). (Figure presented.).
  Scientific journal
  DOI：https://doi.org/10.1002/marc.201600351
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  DOI ID：10.1002/marc.201600351, ISSN：1022-1336, eISSN：1521-3927, SCOPUS ID：84988896833
• Highly Isospecific Polymerization of Silyl-Protected ω-Alkenols Using an [OSSO]-Type Bis(phenolato) Dichloro Zirconium(IV) Precatalyst　　　　　　　　　　　　　　　
  Yusuke Saito; Norio Nakata; Akihiko Ishii
  Macromolecular Rapid Communications, Volume：37, Number：12, First page：969, Last page：974, Jun. 2016
  The coordination polymerization of silyl-protected ω-alkenols such as ω-alken-α-oxytriisopropylsilanes 1 provides poly(ω-alkenyl-α-oxytriisopropylsilalne)s with a highly isospecific microstructure ([mmmm] > 95%) when a combination of [OSSO]-type bis(phenolato) dichloro zirconium(IV) complex 2 and dried methylaluminoxane is used as the precatalyst and activator, respectively. The resulting siloxy-substituted polymers could be efficiently transformed into the corresponding functionalized polyolefins, which contained up to 90% acetyl groups and ≈7% hydroxy groups in the terminal side chains. (Figure presented.) .
  Scientific journal
  DOI：https://doi.org/10.1002/marc.201600123
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  DOI ID：10.1002/marc.201600123, ISSN：1022-1336, eISSN：1521-3927, PubMed ID：27150730, SCOPUS ID：84966350010
• Highly active and isospecific styrene polymerization catalyzed by zirconium complexes bearing aryl-substituted [OSSO]-type bis(phenolate) ligands　　　　　　　　　　　　　　　
  Norio Nakata; Tomoyuki Toda; Yusuke Saito; Takanori Watanabe; Akihiko Ishii
  Polymers, Volume：8, Number：2, 2016
  [OSSO]-type dibenzyl zirconium(IV) complexes 9 and 10 possessing aryl substituents ortho to the phenoxide moieties (ortho substituents, phenyl and 2,6-dimethylphenyl (Dmp)) were synthesized and characterized. Upon activation with dMAO (dried methylaluminoxane), complex 9 was found to promote highly isospecific styrene polymerizations ([mm] = 97.5%-99%) with high molecular weights Mw up to 181,000 g· mmol-1. When the Dmp-substituted pre-catalyst 10/dMAO system was used, the highest activity, over 7700 g· mmol(10)-1· h-1, was recorded involving the formation of precisely isospecific polystyrenes of [mm] more than 99%.
  Scientific journal
  DOI：https://doi.org/10.3390/polym8020031
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  DOI ID：10.3390/polym8020031, eISSN：2073-4360, SCOPUS ID：84960080283
• Copolymerization of ethylene with ⁱPr3Si-protected 5-hexen-1-ol with an [OSSO]-type bis(phenolato) dichloro zirconium(IV) complex　　　　　　　　　　　　　　　
  Yusuke Saito; Norio Nakata; Akihiko Ishii
  Bulletin of the Chemical Society of Japan, Volume：89, Number：6, First page：666, Last page：670, 2016
  The ability of dichlorozirconium(IV) complex 4 incorporating an [OSSO]-type bis(phenolate) ligand with dMAO (dried methylaluminoxane) as an activator for the copolymerization of ethylene with iPr3Si-protected 5-hexen-1-ol, 5-hexen-1-oxytriisopropylsilane (5H1OSi), is described. This catalyst system efficiently promoted ethylene copolymerization with different feed ratios of 5H1OSi at 25 °C under an atmospheric pressure producing ethylene/5H1OSi copolymers with molecular weights Mw of 380010800 gmol-1. In the 1HNMR spectroscopic analysis, the contents of 5H1OSi in the copolymers were found to be in the range of 7.521.4 mol% depending upon the feed concentration of 5H1OSi. The sequence distributions and calculated reactive ratios (γEγP = 1.483.48) obtained from the 13CNMR spectra revealed that the catalytic system produced highly random ethylene/5H1OSi copolymers.
  Scientific journal
  DOI：https://doi.org/10.1246/bcsj.20160043
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  DOI ID：10.1246/bcsj.20160043, ISSN：0009-2673, eISSN：1348-0634, SCOPUS ID：84976463165
• 1,4-diaryl-1-oxy-1,3-butadiene conjugated system incorporated in a dibenzobarrelene skeleton: Synthesis, photophysical properties, and comparison with the heavier group 16 congeners　　　　　　　　　　　　　　　
  Akihiko Ishii; Mari Shibata; Norio Nakata
  Bulletin of the Chemical Society of Japan, Volume：89, Number：12, First page：1470, Last page：1479, 2016
  We have synthesized the 1,4-diaryl-1-thio-, seleno- and telluro-1,3-butadiene derivatives incorporated in a dibenzobarrelene skeleton and found that the thio and seleno derivatives are highly fluorescent in solution at room temperature. We report here the synthesis of the oxygen congener. The compounds were synthesized by the reaction of anthranolate with 1,4-diaryl-1,3-butadiyne followed by an intramolecular cycloaddition. Their structures were analyzed by X-ray crystallography to reveal high planarity of the 1,4-diaryl-1-oxy-1,3-butadiene moieties compared with the heavier chalcogen congeners. The oxy compounds are fluorescent similarly to the thio and seleno congeners; the diphenyl and bis(4-trifluorophenyl) derivatives exhibited somewhat red-shifted fluorescence spectra with vibrational structure. Fluorescence of the D-φ-A type derivatives reached to the red and near infrared regions. The bonding characters in the 1-chalcogeno-1,3-butadiene moieties are discussed on the basis of DFT calculations.
  Scientific journal
  DOI：https://doi.org/10.1246/bcsj.20160287
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  DOI ID：10.1246/bcsj.20160287, ISSN：0009-2673, eISSN：1348-0634, SCOPUS ID：85025803081
• Red and Near-Infrared Photoluminescence of D-π-A-Type Compounds Based on a 1,4-Diaryl-1-thio-1,3-butadiene Conjugated System in a Dibenzobarrelene Skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Yukihiro Makishima; Norio Nakata
  Journal of Organic Chemistry, Volume：80, Number：22, First page：11598, Last page：11604, Nov. 2015
  1,4-Diaryl-1-thio-1,3-butadiene derivatives having a π-donor dimethylamino group and several π-acceptor substituents at both terminals of the conjugated system were synthesized by intramolecular [4 + 2] cycloaddition of 1-thio-enynes and subsequent chemical transformations. They displayed largely red-shifted absorption and emission spectra in solution, the powder state, and in polymer films. The derivatives with a 2,2-dicyanoethenyl group as the π-acceptor exhibited inverted solvatochromism in both optical absorption and fluorescence spectroscopies.
  Scientific journal
  DOI：https://doi.org/10.1021/acs.joc.5b02189
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  DOI ID：10.1021/acs.joc.5b02189, ISSN：0022-3263, eISSN：1520-6904, SCOPUS ID：84947969653
• Extremely active α-olefin polymerization and copolymerization with ethylene catalyzed by a dMAO-activated zirconium(iv) dichloro complex having an [OSSO]-type ligand　　　　　　　　　　　　　　　
  Tomoyuki Toda; Norio Nakata; Tsukasa Matsuo; Akihiko Ishii
  RSC Advances, Volume：5, Number：108, First page：88826, Last page：88831, Oct. 2015
  The ability of a zirconium(iv) dichloro complex (6b) incorporating an [OSSO]-type ligand 5 with dMAO as an activator for the polymerization of 1-hexene and 4-methyl-1-pentene (4-MP) is described. In the polymerization of 1-hexene, the combination of the 6b/dMAO catalyst system efficiently provided poly(1-hexene)s with completely isotactic [mmmm] pentad more than 95% and relatively large molecular weight (Mw = 40 000-150 000 g mol-1). The corresponding activity was recorded with quite high values up to 18 100 g mmol(6b)-1 h-1, which increased significantly compared with those of the related non-Cp complexes. The polymerization of 4-MP using the 6b/dMAO system at different temperatures also gave perfect isotactic poly(4-MP)s ([mmmm] > 95%) with moderate molecular weights (Mw = 7000-21 300 g mol-1), relatively narrow polydispersities (Mw/Mn = 1.5-1.7), and activities of 1220-1690 g mmol(6b)-1 h-1. This catalyst system was also found to promote ethylene copolymerization with different amounts of 1-hexene at 25°C under atmospheric pressure producing random ethylene/1-hexene copolymers (Mw = 10 100-17 300 g mol-1, Mw/Mn = 1.8-1.9, 1-hexene contents = 37.3-66.7 mol%) with fairly high activity up to 2700 g mmol(6b)-1 h-1.
  Scientific journal
  DOI：https://doi.org/10.1039/c5ra20846g
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  DOI ID：10.1039/c5ra20846g, eISSN：2046-2069, SCOPUS ID：84945285608
• A Schrock-Type Germylene Complex: (η⁵-C5H4Et)2(PMe3)Hfi=Ge(SiMe^tBu2)2　　　　　　　　　　　　　　　
  Norio Nakata; Shinji Aoki; Vladimir Ya Lee; Akira Sekiguchi
  Organometallics, Volume：34, Number：11, First page：2699, Last page：2702, Jun. 2015
  The stable group 4 metal germylene complex (η5-C5H4Et)2(PMe3)Hfi=Ge(SiMetBu2)2 (2) is readily available by the reaction of the 1,1-dilithiogermane (tBu2MeSi)2GeLi2 with (η5-C5H4Et)2HfCl2 in toluene at -50 °C, followed by treatment with trimethylphosphine. The hafnium-germanium bond distance of 2.6705(5) Å in 2 is indicative of its double-bond character, being ca. 3-7% shorter than the usual Hf-Ge single bonds. The novel hafnium germylene derivative is classified as a Schrock-type complex, featuring a negatively polarized nucleophilic germanium center. (Figure Presented).
  Scientific journal
  DOI：https://doi.org/10.1021/om501134a
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  DOI ID：10.1021/om501134a, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：84931265678
• Cationic dinuclear platinum and palladium complexes with bridging hydrogermylene and hydrido ligands　　　　　　　　　　　　　　　
  Norio Nakata; Noriko Sekizawa; Akihiko Ishii
  Chemical Communications, Volume：51, Number：50, First page：10111, Last page：10114, May 2015
  Hydride-abstraction reactions of hydrido(dihydrogermyl) complexes [MH(GeH2Trip)(dcpe)] [M = Pt, Pd, Trip = 9-triptycyl, dcpe = 1,2-bis(dicyclohexylphosphino)ethane] with B(C6F5)3 led to the unexpected formation of new cationic (μ-germyl)(μ-hydrido) dinuclear platinum and palladium complexes, [{M(dcpe)}2(μ-GeHTrip)(μ-H)]+.
  Scientific journal
  DOI：https://doi.org/10.1039/c5cc03062e
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  DOI ID：10.1039/c5cc03062e, ISSN：1359-7345, eISSN：1364-548X, SCOPUS ID：84931282130
• Precise polymerization of α-olefins using a mixed donor-type ligand containing oxygen and sulfur atoms　　　　　　　　　　　　　　　
  Norio Nakata; Akihiko Ishii
  Kobunshi Ronbunshu, Volume：72, Number：5, First page：285, Last page：294, May 2015
  Much attention has been paid to the development of so-called post-metallocene complexes as potent single-site catalysts for α-olefin polymerization to achieve high activity and good stereo control. While studies on the syntheses and applications of Group IX metal complexes bearing mixed-donor based [OSSO]-type bis(phenolate) ligands were reported to date, there were few examples to achieve both high activity and stereo specificity during a-olefin polymerization. Recently, we reported the development of a new [OSSO]-type bis(phenolate) ligand based on a trans-1,2-cyclooctanediyl platform and syntheses of a series of Group IX metal complexes. In the presence of an activator, zirconium and hafnium pre-catalysts were found to promote precise isospecific polymerization of 1-hexene or 4-methyl-l-pentene with high activities to give the corresponding polymers with large molecular weights and narrow PDI values. Furthermore, the dibenzyl hafnium complex, upon activation with dMAO, led to the combination of high activity and considerably well controlled isotacticity in the polymerization of propylene at various temperatures.
  Scientific journal
  DOI：https://doi.org/10.1295/koron.2014-0093
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  DOI ID：10.1295/koron.2014-0093, ISSN：0386-2186, SCOPUS ID：84937931055
• Synthesis, Structures, and Temperature-Dependent Photoluminescence of 1,4-Diphenyl-1-telluro-1,3-butadiene Incorporated in a Dibenzobarrelene Skeleton and Derivatives　　　　　　　　　　　　　　　
  Tatsuro Annaka; Norio Nakata; Akihiko Ishii
  Organometallics, Volume：34, Number：7, First page：1272, Last page：1278, Apr. 2015
  1,4-Diphenyl-1-telluro-1,3-butadiene incorporated in a dibenzobarrelene skeleton was synthesized with a good yield by an intramolecular Diels-Alder reaction of the corresponding 1-(9-anthyltelluro)enyne. Oxidation and bromination of the telluride yielded telluroxide and hypervalent Te,Te-dibromide, respectively. Their structures were determined by X-ray crystallography. Unlike its highly fluorescent sulfur and selenium congeners, the telluride is barely fluorescent in solution at room temperature due to the heavy-atom effect of tellurium. The telluride displayed temperature-dependent fluorescence; it is fluorescent with a moderate quantum yield (ΦPL = 0.42) in the glass of 2-methyltetrahydrofuran at 77 K. (Chemical Equation Presented).
  Scientific journal
  DOI：https://doi.org/10.1021/acs.organomet.5b00016
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  DOI ID：10.1021/acs.organomet.5b00016, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：84927731830
• Palladium(0)-mediated C-S and O-H bonds cleavage reaction in 2-hydroxybenzyl phenyl sulfide: Formations of oxyphosphorane and 1,2-oxapalladacycle　　　　　　　　　　　　　　　
  Norio Nakata; Noriyuki Furukawa; Hiroki Kobayashi; Izuru Suzuki; Akihiko Ishii
  Heterocycles, Volume：90, Number：1, First page：144, Last page：149, 2015
  Treatment of 2-hydroxybenzyl phenyl sulfide 3 with 1.5 equiv. of [Pd(PPh3)4] in toluene led to the unanticipated formation of oxyphosphorane 4 in 30% isolated yield. In contrast, the reaction of 3 with Pd(0) complex bearing PMe3 ligands in toluene afforded the corresponding 1,2-oxapalladacycle 7 and oxyphosphorane 9 in addition to dithiolato complex trans-[Pd(SPh)2(PMe3)2] 8.
  Scientific journal
  DOI：https://doi.org/10.3987/COM-14-S(K)45
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  DOI ID：10.3987/COM-14-S(K)45, ISSN：0385-5414, eISSN：1881-0942, SCOPUS ID：84923273116
• Synthesis and photophysical properties of extended π-conjugative and PushPull- type 1,4-diaryl-1-thio-1,3-butadienes incorporated in a dibenzobarrelene skeleton　　　　　　　　　　　　　　　
  Tatsuro Annaka; Norio Nakata; Akihiko Ishii
  Bulletin of the Chemical Society of Japan, Volume：88, Number：4, First page：554, Last page：561, 2015
  1,4-Bis(p-ethynylphenyl)-1-thio-1,3-butadiene derivatives incorporated in a dibenzobarrelene skeleton were yielded by Sonogashira reactions of the corresponding 1,4-bis(p-halophenyl) derivatives, and pushpull- type sulfoxide and sulfone derivatives were obtained by oxidation of the amino derivative prepared by BuchwaldHartwig reaction of the 1,4-bis(p-halophenyl) derivatives. These compounds show red-shifted yellow and orange fluorescence [λcm( CH2Cl2) = 522562 nm, λcm( solid) = 522580 nm] in comparing with the unsubstituted, 1,4-diphenyl-1-thio-1,3-butadiene derivative [λcm( CH2Cl2) = 491 nm, λcm( solid) = 483 nm].
  Scientific journal
  DOI：https://doi.org/10.1246/bcsj.20140351
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  DOI ID：10.1246/bcsj.20140351, ISSN：0009-2673, eISSN：1348-0634, SCOPUS ID：84929472169
• Thiophene-fused 3-methylene-2,3-dihydrochalcogenophenes: Fluorescent dyes incorporated in a rigid dibenzobarrelene skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Shota Kobayashi; Yutaro Aoki; Tatsuro Annaka; Norio Nakata
  Heteroatom Chemistry, Volume：25, Number：6, First page：658, Last page：673, Nov. 2014
  3-Methylene-2,3-dihydrothienothiophene and -selenophenothiophene derivatives incorporated in a rigid dibenzobarrelene skeleton were synthesized by intramolecular Diels-Alder reaction, and their structures, fluorescent properties, and electrochemistry were elucidated. In 3-methylene-2,3-dihydrothieno[3,2-b]thiophene derivatives, silyl and phenyl substituents at the terminal position were effective for strong blue fluorescence (λem = 412-455 nm) with high quantum yields (ΦF = 0.65-0.99), whereas the unsubstituted parent compound was weakly fluorescent (λem = 338 nm, ΦF = 0.03). The phenylsubstituted [3,2-b]-derivative showed strong emission also in the solid state (ΦF = 0.70). The corresponding [2,3-b]-isomer showed blueshifted absorption (λabs = 342 nm) and emission (λem = 436 nm) maxima with low-to-moderate quantum yields in solution (ΦF = 0.24) and in the solid state (ΦF = 0.41). In the case of the selenium congeners (3-methylene-2,3-dihydroselenopheno[3,2-b]thiophene derivatives), the heavy atom effect due to the selenium was decisive to decrease the quantum yields (ΦF = 0.01-0.06). The oxidation of phenyl-substituted [3,2-b]-derivative yielded the corresponding sulfoxide and sulfone, which showed strong emission at around 440 nm with high quantum yields in dichloromethane (ΦF = 0.91 and 0.98, respectively). A dimer of the phenyl-substituted [3,2-b]-derivative was prepared by oxidative coupling of the lithio derivative. The dimer had weak redshifted emission (λem = 547 nm, ΦF = 0.10) and showed a reversible cyclic voltammogram with E1/2 = 0.35 V versus Fc/Fc+ redox couple.
  Scientific journal
  DOI：https://doi.org/10.1002/hc.21185
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  DOI ID：10.1002/hc.21185, ISSN：1042-7163, eISSN：1098-1071, SCOPUS ID：84915754560
• Reactions of bis(dibenzobarrelenyl) dichalcogenides with a palladium(0) complex: Unexpected formations of mononuclear chalcogenide(dichalcogenolato)palladium(II) complexes and dichalcogenahexacyclo compounds　　　　　　　　　　　　　　　
  Norio Nakata; Yuki Yamaguchi; Akihiko Ishii
  European Journal of Inorganic Chemistry, Volume：2014, Number：30, First page：5177, Last page：5184, Oct. 2014
  Thermal reactions of bis(dibenzobarrelenyl) dichalcogenides (E = S, Se) together with dichalcogenahexacyclo compounds. The reaction in the presence of PPh3 in toluene at 110 C led to a cyclometalation to furnish the corresponding four-membered 1,2-chalcogenapalladacycles [Pd(EDbb)(PPh3)2] (E = S, Se) with dichalcogenahexacyclo compounds. The structures of these PdII complexes and cyclization products were fully characterized on the basis of their NMR spectroscopic data and X-ray analyses. In the crystalline state of [Pd(SDbb-12-SDbb)(SDbb)(PPh3)], two thiolato sulfur atoms occupy cis positions with respect to the PPh3, and the sulfide sulfur atom from the chelating sulfido(thiolato) ligand is situated at the trans position.
  Scientific journal
  DOI：https://doi.org/10.1002/ejic.201402518
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  DOI ID：10.1002/ejic.201402518, ISSN：1434-1948, eISSN：1099-0682, SCOPUS ID：84949114924
• Synthesis of 4-chalcogeno-1-aza-1,3-butadiene derivatives by intramolecular cyano-Diels-Alder reaction and borane-coordination-induced fluorescence enhancement　　　　　　　　　　　　　　　
  Akihiko Ishii; Yutaro Aoki; Norio Nakata
  Journal of Organic Chemistry, Volume：79, Number：17, First page：7951, Last page：7960, Sep. 2014
  4-Thio-1-aza-1,3-butadiene derivatives 3 incorporating a rigid dibenzobarrelene skeleton were synthesized by the intramolecular cyano-Diels-Alder reaction of 9-anthryl cyanoethenyl sulfides 6. The thermal reaction of 6 afforded an equilibrium mixture of 3 and 6, but the cyclization was effectively promoted by the addition of BF3·Et2O or B(C6F5)3 to yield imine-borane adducts 8 and 9. The imine-borane adducts emit intense blue fluorescence both in solution and in the crystalline state. This is in stark contrast to free imines 3, which are weakly fluorescent. Selenium analogue 4 and N-oxide 12 of 3a were synthesized, along with their B(C6F5)3 adducts.
  Scientific journal
  DOI：https://doi.org/10.1021/jo501103e
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  DOI ID：10.1021/jo501103e, ISSN：0022-3263, eISSN：1520-6904, SCOPUS ID：84924325913
• Completely isospecific polymerization of 1-hexene catalyzed by hafnium(IV) dichloro complex incorporating with an [OSSO]-type bis(phenolate) ligand　　　　　　　　　　　　　　　
  Norio Nakata; Yusuke Saito; Takanori Watanabe; Akihiko Ishii
  Topics in Catalysis, Volume：57, Number：10-13, First page：918, Last page：922, Jun. 2014
  In the presence of dried methylaluminoxane as an activator, the hafnium(IV) dichloro pre-catalyst 4 incorporating with an [OSSO]-type ligand was found to promote precisely isospecific 1-hexene polymerizations of [mmmm] up to 95 % with fairly high activities (1,050-3,180 g mmol(4)-1 h-1) and relatively narrow polydispersities (M w/M n = 1.5-1.8). © 2014 Springer Science+Business Media New York.
  International conference proceedings
  DOI：https://doi.org/10.1007/s11244-014-0252-1
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  DOI ID：10.1007/s11244-014-0252-1, ISSN：1022-5528, SCOPUS ID：84902660124
• Neutral methyl and cationic aluminum complexes supported by a trans-1,2-cyclooctanediyl-bridged [OSSO]-type bis(phenolato) ligand: Synthesis, structures, and use in catalysis for propylene oxide polymerization　　　　　　　　　　　　　　　
  Norio Nakata; Yusuke Saito; Akihiko Ishii
  Organometallics, Volume：33, Number：7, First page：1840, Last page：1844, Apr. 2014
  Treatment of trans-1,2-cyclooctanediyl-bridged [OSSO]-type bis(phenolate) 1 with Me3Al in hexane led to the formation of methylaluminum 4 as colorless crystals. X-ray diffraction analysis of 4 revealed that the aluminum center adopts a distorted-trigonal-bipyramidal geometry which occupies the axial positions with one phenoxide oxygen and one sulfur atoms. The dealkylation reaction of 4 with 1 equiv of B(C6F5)3 in C6D6 afforded the novel cationic aluminum species 5 2+ as a dimeric structure, which was isolated in the form of a [MeB(C6F5)3]- salt. In the crystal structure of 52+, one aluminum atom has a distorted-trigonal- bipyramidal environment, in which phenoxide and μ-bridging oxygen atoms are located at two axial positions, whereas the other aluminum atom has a distorted-square-pyramidal geometry, which occupies the axial position with a nonbridged oxygen atom. The cationic species 52+ promoted the ring-opening polymerization (ROP) of propylene oxide to give an atactic polymer in 44% yield with a low molecular weight (Mn = 2500) and a very narrow molecular weight distribution (PDI = 1.04). © 2014 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om5001698
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  DOI ID：10.1021/om5001698, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：84898621575
• Characterization and phenylacetylene-assisted cyclometalation of an isolable hydrido-selenolato Pt^II complex having phosphite ligands, cis-[PtH(SeTrip){P(OPh)3}2]^#　　　　　　　　　　　　　　　
  Hitomi Kamon; Yutaro Aoki; Norio Nakata; Akihiko Ishii
  Bulletin of the Chemical Society of Japan, Volume：87, Number：2, First page：274, Last page：282, 2014
  A hydridoselenolato PtII complex having P(OPh)3 ligands, cis-[PtH(SeTrip){P(OPh)3}2] (Trip: 9-triptycyl), was synthesized by the reaction of TripSeH with [Pt{P(OPh)3} 2]. The structure was characterized by NMR spectroscopy and X-ray crystallography in comparison with the corresponding PPh3 complex, cis-[PtH(SeTrip)(PPh3)2], indicating the stronger coordination of P(OPh)3 to the Pt center than that of PPh 3. On heating at 130 °C in xylene for 17 h, cis-[PtH(SeTrip)- {P(OPh)3}2] was converted to the corresponding 1,2-selenaplatinacycle (SP-42)-[Pt(kC1,kSe9-TripSe(2-)) {P(OPh)3}2] through an intramolecular cyclization (cyclometalation). The reaction with dimethyl acetylenedicarboxylate (DMAD) gave a mixture of hydroselenation products (E)- and (Z)-(MeO2C)CH= C(SeTrip)CO2Me non-stereoselectively together with 1H-2-benzoselenin, dimethyl 7H-7,11b[1',2']-benzenoanthra[9,1-bc]selenin-2,3-dicarboxylate. In the reaction with phenylacetylene in toluene at 110 °C, phenylacetylene served as a hydrogen acceptor to form the 1,2-selenaplatinacycle and styrene. Based on the results of controlled experiments using cis-[PtD(SeTrip){P(OPh) 3}2] and phenylacetylene-d, the mechanism of the cyclometalation was proposed as the 1,2- (major) and 2,1- (minor) insertions of phenylacetylene into the Pt-H bond followed by cyclometalation between the Pt center and the triptycyl group. The reaction with phenylacetylene in the presence of excess P(OPh)3 furnished a 1,2,3-oxaphosphaplatinacycle, (SP-4-2)-[Pt{kC,kP-(Z)-CH=C(Ph)-OP(OPh)2}(SeTrip){P(OPh) 3}], as a minor product, together with the 1,2-selenaplatinacycle in a decreased yield. © 2013 The Chemical Society of Japan.
  Scientific journal
  DOI：https://doi.org/10.1246/bcsj.20130295
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  DOI ID：10.1246/bcsj.20130295, ISSN：0009-2673, eISSN：1348-0634, SCOPUS ID：84894287341
• Synthesis of [SSSS]-type bis(thiophenol) ligand based on a trans -cyclooctane-1,2-diyl(thio) platform and an unexpected reaction with platinum complexes to produce sulfide-bis(thiolato) Pt^II complex　　　　　　　　　　　　　　　
  Hiroki Mikami; Eriko Toyoda; Norio Nakata; Akihiko Ishii
  Journal of Sulfur Chemistry, Volume：34, Number：6, First page：661, Last page：670, Dec. 2013
  A new [SSSS]-type bis(thiophenol) ligand based on a trans-cyclooctane-1,2- diyl(thio) platform was prepared by the reaction of trans-cyclooctane-1,2- dithiol with 2 mol equiv. of 3,5-di-tert-butyl-2- (2-cyanoethylthio)benzyl bromide followed by deprotection. The reactions of the [SSSS]-type ligand with [Pt(nb)(PPh3)2] (nb=norbornene) or [PtCl 2(PPh3)2] complexes produced unexpectedly a [sulfide-bis(thiolato)]-PPh3 PtII complex accompanying loss of one of the 2-sulfanylbenzyl groups. The structure of the PtII complex was determined by X-ray crystallography. The physical property and formation mechanism for the PtII complex are discussed. © 2013 Taylor & Francis.
  Scientific journal
  DOI：https://doi.org/10.1080/17415993.2013.781605
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  DOI ID：10.1080/17415993.2013.781605, ISSN：1741-5993, eISSN：1741-6000, SCOPUS ID：84889565144
• A stable silene substituted by strong π-donors at the silicon center　　　　　　　　　　　　　　　
  Norio Nakata; Ricardo Rodriguez; Thibault Troadec; Nathalie Saffon-Merceron; Jean Marc Sotiropoulos; Antoine Baceiredo; Tsuyoshi Kato
  Angewandte Chemie - International Edition, Volume：52, Number：41, First page：10840, Last page：10844, Oct. 2013
  Keen to donate: A stable and isolable silene with two π-donating groups on the silicon center has been synthesized. This silicon-substituted silene shows totally different π-substituent effects compared to those of related carbon-substituted silenes, and it presents intrinsic silene properties with an enhanced electron-donating character, making it an excellent ligand for transition metals. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.201304594
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  DOI ID：10.1002/anie.201304594, ISSN：1433-7851, eISSN：1521-3773, SCOPUS ID：84885125251
• Strong solid-state phosphorescence of 1,2-telluraplatinacycles incorporated into rigid dibenzobarrelene and triptycene skeletons　　　　　　　　　　　　　　　
  Yuki Yamaguchi; Norio Nakata; Akihiko Ishii
  European Journal of Inorganic Chemistry, Number：30, First page：5233, Last page：5239, Oct. 2013
  Four- and five-membered 1,2-telluraplatinacycles incorporated into dibenzobarrelene and triptycene skeletons were synthesized by the reaction of bis(dibenzobarrelenyl) ditelluride and bis(triptycyl) ditelluride, respectively, with [Pt(η2-norbornene)(PPh3)2] in the presence of PPh3. These complexes emit strong, orange phosphorescence in the solid state at room temperature (λem = 622-676 nm). Ligand-exchange reactions of a five-membered telluraplatinacycle with bidentate phosphine ligands gave a series of derivatives that emitted a range of colors (blue to orange, λem = 507-596 nm) with high emission quantum yields (max. ΦF = 0.93) in the solid state at room temperature, for which vapoluminescence was observed. Four- and five-membered 1,2-telluraplatinacycles incorporated into dibenzobarrelene and triptycene skeletons phosphoresce strongly in the solid state at room temperature. Ligand-exchange reactions of the latter gives a series of derivatives that emit a range of colors (blue to orange) with high emission quantum yields (max ΦF = 0.93). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  Scientific journal
  DOI：https://doi.org/10.1002/ejic.201301104
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  DOI ID：10.1002/ejic.201301104, ISSN：1434-1948, eISSN：1099-0682, SCOPUS ID：84885662459
• Controlled isospecific polymerization of α-olefins by hafnium complex incorporating with a trans -cyclooctanediyl-bridged [OSSO]-type bis(phenolate) ligand　　　　　　　　　　　　　　　
  Norio Nakata; Tomoyuki Toda; Tsukasa Matsuo; Akihiko Ishii
  Macromolecules, Volume：46, Number：17, First page：6758, Last page：6764, Sep. 2013
  Treatment of trans-cyclooctanediyl-bridged [OSSO]-type ligand 1 with Hf(CH2Ph)4 in toluene afforded the corresponding hafnium(IV) dibenzyl complex 5 as pale yellow crystals. X-ray crystallographic analysis of 5 revealed that the six-coordinated hafnium center incorporated in the [OSSO]-type ligand 1 adopted cis-α configuration, and two benzyl ligands were coordinated to hafnium center by η1-fashion. In the polymerization of 1-hexene, the combination of hafnium complex 5 and B(C 6F5)3, (Ph3C)[B(C6F 5)4], or dMAO (dried methylaluminoxane) as an activator provided poly(1-hexene)s with perfect isotacticity ([mmmm] > 95%) and high molecular weights (Mw = 74 800-421 000 g mol-1). The combination of 5/dMAO catalyst system, in particular, exhibited fairly high activity of 2100 g mmol (5)-1 h-1, which is quite higher than those of previously reported [OSSO]-type hafnium complexes. In addition, the polymerization of 4-methyl-1-pentene (4-MP) catalyzed by the 5/(Ph 3C)[B(C6F5)4] system at room temperature produced completely isotactic poly(4-MP)s with good activity (54-101 g mmol (5)-1 h-1) and relatively narrow PDI (M w/Mn = 1.3). Furthermore, the propylene polymerization catalyzed by the 5/dMAO system at different temperatures (0-70 C) for 1 h afforded highly isotactic polypropylenes, where the catalyst activity and isotacticity depend on the polymerization temperature. Thus, the activity greatly increased from 500 to 17 000 g mmol (5)-1 h-1 when the polymerization temperature was increased. In contrast, isotacticity and melting transition temperature (Tm) were elevated by decreasing polymerization temperature (at 0 C: [mmmm] = 93.7%, Tm = 156.2 C; at 70 C: [mmmm] = 86.8%, Tm = 140.9 C). © 2013 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ma401115v
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  DOI ID：10.1021/ma401115v, ISSN：0024-9297, eISSN：1520-5835, SCOPUS ID：84884197879
• Synthesis, structure, and 1-hexene polymerization catalytic ability of group 5 metal complexes incorporating an [OSSO]-type ligand　　　　　　　　　　　　　　　
  Tomoyuki Toda; Norio Nakata; Tsukasa Matsuo; Akihiko Ishii
  ACS Catalysis, Volume：3, Number：8, First page：1764, Last page：1767, Aug. 2013
  Group 5 metal complexes bearing an [OSSO]-type bis(phenolate) ligand have been successfully prepared by the reaction of a bis(phenol) compound 3 or its dilithio salt 6 with VO(OPr)3, NbCl5, or TaCl5. X-ray crystallographic analyses revealed the monomeric nature of the resulting complexes, [OSSO]VO(OPr) (5), [OSSO]NbCl3 (7), and [OSSO]TaCl 3 (8), where the metal centers adopted cis-α configurations of the [OSSO] tetradentate ligand. The tantalum(V) complex 8 with iBu3Al/(Ph3C)[B(C6F 5)4] as an activator catalyzed the polymerization of 1-hexene to provide completely isotactic poly(1-hexene), with a narrow molecular weight distribution ([mmmm] > 95%, Mw = 9100 g mol-1, PDI = 1.6); this is the first group 5 metal catalyst for α-olefin polymerization to afford a highly isospecific polymer. © 2013 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/cs4003996
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  DOI ID：10.1021/cs4003996, ISSN：2155-5435, SCOPUS ID：84881273452
• The mechanism for transition-metal-catalyzed hydrochalcogenation of unsaturated organic molecules　　　　　　　　　　　　　　　
  Akihiko Ishii; Norio Nakata
  Topics in Organometallic Chemistry, Volume：43, First page：21, Last page：50, 2013
  In this chapter, discussions are focused on two types of mechanisms of transition-metal-catalyzed hydrochalcogenation, Type I and Type II, which are classified by the initial behavior of precatalysts. In Type I mechanism, precatalyst M-X (M = Pd, Ni, Zr, Ln, and An) first undergoes protonolysis with REH (E = O, S, and Se) to generate active catalyst M-ER, which then undergoes insertion of alkyne into the M-ER bond (chalcogenometalation) to give 2-chalcogenovinyl complex, followed by protonolysis of M-C vinyl with REH to produce the product and to regenerate active catalyst M-ER. Type II mechanism starts from oxidative addition of REH (E = S and Se) to complex [M] (M = Pd, Pt, Rh, and Ir) to give chalcogenolato-hydrido complex, [M]H(ER). In the next alkyne insertion, [M]-H insertion (hydrometalation) to give [M](ER)(vinyl) or [M]-E insertion (chalcogenometalation) to give [M]H(2-RE-vinyl) occurs and then reductive elimination of the resulting vinyl [M] complexes yields the product and [M]. Reactions where transition metal catalysts exert as Lewis acid to activate unsaturated bonds and those proceeding through vinylidene intermediates are mentioned only shortly. © 2013 Springer-Verlag Berlin Heidelberg.
  Scientific journal
  DOI：https://doi.org/10.1007/3418-2011-16
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  DOI ID：10.1007/3418-2011-16, ISSN：1436-6002, SCOPUS ID：84869077106
• Convenient syntheses and photophysical properties of 1-thio- and 1-seleno-1,3-butadiene fluorophores in rigid dibenzobarrelene and benzobarrelene skeletons　　　　　　　　　　　　　　　
  Akihiko Ishii; Tatsuro Annaka; Norio Nakata
  Chemistry - A European Journal, Volume：18, Number：21, First page：6428, Last page：6432, May 2012
  No heavy-atom effect: Highly fluorescent, sulfur- or selenium-containing compounds were synthesized by intramolecular [4+2]-cycloadditions between 9-anthryl or 1-naphthyl and alkynyl moieties (see scheme). Their fluorescence is based on a 1-chalcogeno-1,3-butadiene-conjugated system in a rigid skeleton. Some of them are also highly fluorescent in the solid state. The monoxide of Mbb-S is more fluorescent in the solid state (φ F=0.6) than in solution (φ F<0.02). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  Scientific journal
  DOI：https://doi.org/10.1002/chem.201200761
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  DOI ID：10.1002/chem.201200761, ISSN：0947-6539, eISSN：1521-3765, PubMed ID：22517430, SCOPUS ID：84861163970
• Titanium complexes supported by an [OSSO]-type bis(phenolato) ligand based on a trans -cyclooctanediyl platform: Synthesis, structures, and 1-hexene polymerization　　　　　　　　　　　　　　　
  Norio Nakata; Tomoyuki Toda; Tsukasa Matsuo; Akihiko Ishii
  Inorganic Chemistry, Volume：51, Number：1, First page：274, Last page：281, Jan. 2012
  trans-Cyclooctanediyl-bridged [OSSO]-type ligand 4 reacts with TiCl 4(thf) 2 in toluene to produce the corresponding titanium(IV) dichloro complexes as an inseparable mixture of cis-α isomer 6a and cis-β isomer 6b in a ratio of 2:1, whereas treatment of dilithio salt of 4 with TiCl 3(thf) 3 in Et 2O afforded chloride-bridged dimeric titanium(III) complex 8, which indicated the antiferromagnetic character in a nonpolar solvent solution. Di(isopropoxy) titanium(IV) complex 10 having a C 2-symmetric cis-α configuration was synthesized by the reaction of 4 with Ti(O iPr) 4 in toluene as yellow crystals. Moreover, the reaction of 4 with Ti(NEt 2) 4 in toluene resulted in the unexpected formation of [OSSO]-type bis(phenolato)-bridged dinuclear diamido titanium(IV) complex 11, which adopted a distorted tetrahedral geometry on the titanium center. These titanium complexes were characterized on the basis of their NMR spectroscopic data, and the molecular structures of complexes 8, 10, and 11 were established by single crystal X-ray diffraction. The titanium(IV) and (III) complexes 6 and 8 upon activation with a cocatalyst in toluene polymerized 1-hexene isospecifically to produce poly(1-hexene) having high molecular weight (M w = 22,000-52,000 g mol -1) and relatively narrow polydispersity (M w/M n = 1.7-1.8), albeit with low activity [0.27-1.0 g mmol(cat) -1 h -1]. © 2011 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ic2016484
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  DOI ID：10.1021/ic2016484, ISSN：0020-1669, SCOPUS ID：84855375983
• Palladium(II) hydrido complexes having a primary silyl or germyl ligand: Synthesis, crystal structures, and dynamic behavior　　　　　　　　　　　　　　　
  Norio Nakata; Shun Fukazawa; Nanami Kato; Akihiko Ishii
  Organometallics, Volume：30, Number：17, First page：4490, Last page：4493, Sep. 2011
  The first examples of palladium(II) hydrido complexes having a dihydrosilyl or dihydrogermyl ligand, [PdH(EH2Trip)(dcpe)] (E = Si (2), Ge (4); dcpe = 1,2-bis(dicyclohexylphosphino)ethane), were synthesized by oxidative addition of an overcrowded primary silane and germane, TripEH3 (E = Si (1), Ge (3); Trip = 9-triptycyl) with [(μ-dcpe)Pd]2 in toluene. The molecular structures of complexes 2 and 4 were established by single-crystal X-ray analysis, which showed a distorted-square-planar geometry around the palladium centers, probably due to the steric requirements of the chelating dcpe ligand and the bulky 9-triptycyl group on the silicon or germanium atom. A variable-temperature NMR experiment on the palladium silyl complex 2 indicated that the intramolecular interchange of coordination environments between the silyl and hydrido ligands through an Si-H σ-complex intermediate occurs on the NMR time scale. © 2011 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om200576f
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  DOI ID：10.1021/om200576f, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：80052492458
• Fluorescent 3-methylene-2,3-dihydrochalcogenophenes incorporated in a rigid dibenzobarrelene skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Yuki Yamaguchi; Norio Nakata
  Organic Letters, Volume：13, Number：14, First page：3702, Last page：3705, Jul. 2011
  The fluorescent 3-methylene-2,3-dihydroselenophene derivative (ΦF = 0.86 in CH2Cl2) incorporated in a dibenzobarrelene skeleton was synthesized by the reaction of a four-membered selenaplatinacycle with dimethyl acetylenedicarboxylate (DMAD) or reaction of bis(dibenzobarrelenyl) diselenide with DMAD in the presence of Pd(PPh 3)4 and PPh3. A fluorescent sulfur homologue (ΦF = 1.0 in CH2Cl2) was also synthesized by the reaction of bis(dibenzobarrelenyl) disulfide with DMAD in the presence of Pd(PPh3)4. Selected chemical transformations of these diesters were also investigated. © 2011 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ol2013523
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  DOI ID：10.1021/ol2013523, ISSN：1523-7060, eISSN：1523-7052, PubMed ID：21688857, SCOPUS ID：79960192964
• Synthesis of titanium(IV) and zirconium(IV) complexes with an [OSSO]-type bis(phenolate) ligand bearing a trans-cyclohexane-1,2-diyl ring and 1-hexene polymerization　　　　　　　　　　　　　　　
  Akihiko Ishii; Kanako Asajima; Tomoyuki Toda; Norio Nakata
  Organometallics, Volume：30, Number：11, First page：2947, Last page：2956, May 2011
  The Ti(IV) and Zr(IV) complexes 9 and 11 with a new [OSSO]-type bis(phenolate) ligand bearing a trans-cyclohexane-1,2-diyl ring (6) were synthesized. The reaction of 6 with Ti(OiPr)4 in toluene gave the two C2-symmetric, diastereomeric Ti complexes (Λ*,S*, S*)-9 and (Δ*,S*,S*)-9, the latter of which was characterized by X-ray crystallography. The reaction of 6 with Zr(CH 2Ph)4 also provided a mixture of the two C 2-symmetric diastereomers (Λ*,S*,S*)-11 and (Δ*,S*,S*)-11. Polymerization of 1-hexene employing 11 as the precatalyst yielded isotactic poly(1-hexene) with high activity. In relation to the activity, an NMR study was carried out for the cationic zirconium complex 12+[B(CH2Ph)(C6F 5)3]- in comparison with the corresponding complex 13+[B(CH2Ph)(C6F5) 3]-, bearing a trans-cyclooctane-1,2-diyl ring in the ligand. © 2011 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om101131k
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  DOI ID：10.1021/om101131k, ISSN：0276-7333, eISSN：1520-6041, SCOPUS ID：79958097029
• Synthesis and structures of dialkyl zirconium complexes with an [OSSO]-type bis(phenolate) ligand bearing a trans-1,2-cyclooctanediylbis(thio) unit　　　　　　　　　　　　　　　
  Tomoyuki Toda; Norio Nakata; Tsukasa Matsuo; Akihiko Ishii
  Journal of Organometallic Chemistry, Volume：696, Number：6, First page：1258, Last page：1261, Mar. 2011
  Dimethyl and bis[(trimethylsilyl)methyl] zirconium complexes ([OSSO]ZrR2) [4, R = Me; 5, R = CH2SiMe3] having [OSSO]-type bis(phenolato) ligand 1 based on the trans-1,2- cyclooctanediylbis(thio) core have been synthesized by the reactions of the corresponding dichloro zirconium complex 3 with 2 equiv. of MeMgBr and Me 3SiCH2MgCl, respectively, in Et2O/toluene at -78 °C. The molecular structures of these complexes 3-5 were characterized by NMR spectroscopy, elemental analyses, and X-ray crystallography. 1H and 13C NMR data of complexes 3-5 exhibited that they took the C2-symmetry in solution in the NMR time scale. In the crystal structures of 3-5, each zirconium center lies at the center of a distorted octahedral coordination sphere with cis sulfur atoms and trans oxygen atoms, which adopts a cis-α configuration. © 2010 Elsevier B.V. All rights reserved.
  International conference proceedings
  DOI：https://doi.org/10.1016/j.jorganchem.2010.11.035
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  DOI ID：10.1016/j.jorganchem.2010.11.035, ISSN：0022-328X, SCOPUS ID：79952360178
• Syntheses, structures, and complexation of cis- and trans-cycloheptane-1,2- diyl-fused crown thioethers ([12]ansS4)　　　　　　　　　　　　　　　
  Akihiko Ishii; Sohei Asami; Yoko Fujiwara; Aya Ono; Norio Nakata
  Heteroatom Chemistry, Volume：22, Number：3-4, First page：388, Last page：396, 2011
  cis- and trans-Cycloheptane-1,2-diyl-fused crown thioethers ([12]ansS 4), 2,3-cis- and 2,3-trans-cycloheptano-1,4,7,10- tetrathiacyclododecanes (cis-2 and (±)-trans-2), were synthesized from newly prepared cis- and trans-cycloheptane-1,2-ditiols, respectively. X-ray diffraction analyses on cis-2 and (-)-trans-2, which was obtained by optical resolution of (±)-trans-2 with a chiral column, showed that in cis-2 the S-C-C-S part fused with the cis-cycloheptane-1,2-diyl adopted a gauche orientation and that in (-)-trans-2 all S-C-C-S parts took anti-conformations. A competitive complexation experiment of cis-2 and (±)-trans-2 with AgOTf revealed that cis-2 was more favorable than (±)-trans-2 for the complexation. The structure of [Ag(cis-2)]NO3 was analyzed by X-ray crystallography. © 2011 Wiley Periodicals, Inc.
  Scientific journal
  DOI：https://doi.org/10.1002/hc.20695
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  DOI ID：10.1002/hc.20695, ISSN：1042-7163, eISSN：1098-1071, SCOPUS ID：79959620308
• Coordination chemistry and organic synthesis utilizing cycloalkane-1,2- dithiol　　　　　　　　　　　　　　　
  Akihiko Ishii; Tomoyuki Toda; Norio Nakata; Tsukasa Matsuo
  Phosphorus, Sulfur and Silicon and the Related Elements, Volume：186, Number：5, First page：1169, Last page：1174, 2011
  An [OSSO]-type tetradentate ligand was prepared starting from trans-cyclooctane-1,2-dithiol. Hexacoordinated dibenzyl Zr complex was synthesized by the reaction of the ligand with Zr(CH2Ph)4 and its structure was fully characterized by nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography. The zirconium complex has the C 2 symmetry in solution. The zirconium complex activated with B(C 6F5)3 or (Ph3C)[B(C 6F5)4] provided a highly active catalytic system for coordinate polymerization of 1-hexene to yield poly(1-hexene)s with high isospecificity. Copyright © Taylor & Francis Group, LLC.
  International conference proceedings
  DOI：https://doi.org/10.1080/10426507.2010.520283
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  DOI ID：10.1080/10426507.2010.520283, ISSN：1042-6507, eISSN：1563-5325, SCOPUS ID：79960501518
• Syntheses of selenolato-bridged dinuclear hydridoplatinum complexes [Pt2H2(μ-Se^tBu)2(PPh 3)2] and [Pt2H(Se^tBu)(μ-Se ^tBu)2(PPh3)2]: Unusual thermal reaction of hydrido(1,1-dimethylethaneselenolato)　　　　　　　　　　　　　　　
  Norio Nakata; Takashige Ikeda; Akihiko Ishii
  Inorganic Chemistry, Volume：49, Number：17, First page：8112, Last page：8116, Sep. 2010
  Novel selenolato-bridged dinuclear hydridoplatinum complexes, cis-[Pt 2H2(μ-SetBu)2(PPh 3)2] (2) and cis-[Pt2H(SetBu)(μ- SetBu)2(PPh3)2] (3) were synthesized in 30% and 57% yields, respectively, by the thermolysis of hydrido(1,1- dimethylethaneselenolato) Pt(II) complex cis-[PtH(SetBu)(PPh 3)2] (1) in toluene at 80 °C for 3 h. The structures of dinuclear complexes 2 and 3 were fully characterized on the basis of their NMR and IR spectroscopic data and X-ray crystallography. The two distorted square planar Pt atoms in 2 and 3 are held together by two bridged selenolato ligands, tBu groups of which adopt a trans configuration with respect to the four-membered Pt2Se2 ring. Each central Pt 2Se2 ring in 2 and 3 has a hinged arrangement due to the steric repulsion among the two PPh3 ligands and the tBu group lying between them. © 2010 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ic1011742
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  DOI ID：10.1021/ic1011742, ISSN：0020-1669, SCOPUS ID：77956252949
• Cleavage of C-S and O-H bonds by platinum(O) complexes to give five-membered 1,2-oxaplatinacycles　　　　　　　　　　　　　　　
  Norio Nakata; Noriyuki Furukawa; Tomoyuki Toda; Akihiko Ishii
  Angewandte Chemie - International Edition, Volume：49, Number：33, First page：5784, Last page：5787, Aug. 2010
  chemical equation presented Spectacular platinum(0): 1,2-Oxaplatinacycles 2 were formed unexpectedly from 2-hydroxybenzyl sulfide derivatives 1 by bond cleavage mediated by platinum(O) (see scheme; nb = norbornene). The thermal reaction of 2 gave novel six-membered 1,2,3-oxaphosphaplatinacycles through ring expansion accompanied by the insertion of a phosphorus atom into the Pt-O bond and the 1,2-shift of a phenyl group. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.201001937
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  DOI ID：10.1002/anie.201001937, ISSN：1433-7851, eISSN：1521-3773, SCOPUS ID：77955335498
• Reactions of 7,8-dithiabicyclo[4.2.1]nona-2,4-diene 7-exo-oxide with dodecacarbonyl triiron Fe3(CO)12: A novel type of sulfenato thiolato diiron hexacarbonyl complexes　　　　　　　　　　　　　　　
  Jochen Windhager; Ulf Peter Apfel; Tomoharu Yoshino; Norio Nakata; Helmar Gçrls; Manfred Rudolph; Akihiko Ishii; Wolfgang Weigand
  Chemistry - An Asian Journal, Volume：5, Number：7, First page：1600, Last page：1610, Jul. 2010
  The reaction of Fe3(CO)12 (13) with 7,8-dithiabicyclo[4.2.1]nona-2,4-diene 7-exo-oxide (12) yields the sulfenato-thiolato complex 14, which is used as starting material for further reactions. The disulfenato complex 17 is obtained by using one equivalent of dimethyldioxirane (DMD), and the monoepoxide 18 is prepared by the oxidation of 14 with an excess of DMD. Complex 14 can be converted to the monophosphine complexes 19 a and 19b by subsequent substitution of one CO ligand using trimethylaminoxide Me3NO and triphenylphosphine PPh3. Additional substitution reactions are done with 17 by using acetonitrile as a ligand to form 20 a and 20b. In the electrochemical part of the paper, the reactions of the reduced iron species 14, 15, 17, and 19 a are studied. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
  Scientific journal
  DOI：https://doi.org/10.1002/asia.200900733
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  DOI ID：10.1002/asia.200900733, ISSN：1861-4728, eISSN：1861-471X, SCOPUS ID：77954342916
• Spiro[2,5-dibenzo-1,4-disilacyclohexa-2,5-diene-1,7′-2′, 5′- dibenzo-1′,4′,7′-trisilanorbornadiene]: Unusual dimerization of silyl-substituted 9,10-disila(dewar anthracene)　　　　　　　　　　　　　　　
  Norio Nakata; Sayaka Masubuchi; Akira Sekiguchi
  Phosphorus, Sulfur and Silicon and the Related Elements, Volume：185, Number：5-6, First page：957, Last page：963, May 2010
  The reduction of 9,10-dibromo-9,10-dihydro-9,10-disilaanthracene (3) with 2.2 equiv. of KC8 in THF afforded the unexpected spiro[2,5-dibenzo-1,4- disilacyclohexa-2,5-diene-1,7′-2′,5′-dibenzo-1′, 4′,7′-trisilanorbornadiene] (4) through the dimerization of the transient 9,10-disila-9,10-Dewar anthracene (5). The formation of 5 was demonstrated by low-temperature NMR spectroscopy. Copyright © Taylor & Francis Group.
  Scientific journal
  DOI：https://doi.org/10.1080/10426501003771385
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  DOI ID：10.1080/10426501003771385, ISSN：1042-6507, eISSN：1563-5325, SCOPUS ID：77952971950
• Synthesis and properties of hydrido(selenolato)platinum(II) complexes bearing chelating phosphine ligands　　　　　　　　　　　　　　　
  Norio Nakata; Tomoharu Yoshino; Akihiko Ishii
  Phosphorus, Sulfur and Silicon and the Related Elements, Volume：185, Number：5-6, First page：992, Last page：999, May 2010
  The reactions of an overcrowded selenol, TripSeH (1, Trip = 9-triptycyl) with [PtCl2L] (L = dppe, dppf), in the presence of NaBH4 afforded the corresponding hydrido(selenolato) platinum(II) complexes [PtH(SeTrip)(L)] [2 (L = dppe), 3 (L = dppf)]. Complexes 2 and 3 were fully characterized by NMR and IR spectroscopies, and their molecular structures were determined by X-ray crystallography. Thermal reaction of 2 or treatment of 2 with an excess amount of HBF4 produced five-membered selenaplatinacycle [Pt(η2-C,Se-Trip)(dppe)] 4 in moderate yields. Copyright © Taylor & Francis Group.
  Scientific journal
  DOI：https://doi.org/10.1080/10426501003772078
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  DOI ID：10.1080/10426501003772078, ISSN：1042-6507, eISSN：1563-5325, SCOPUS ID：77953005275
• Synthesis and thermal reaction of hydrido(selenolato) platinum(II) complex having a 9,10,11,12,14,15-hexahydro-9,10[3′,4′]-furanoanthracenyl group　　　　　　　　　　　　　　　
  Norio Nakata; Yuki Yamaguchi; Akihiko Ishii
  Journal of Organometallic Chemistry, Volume：695, Number：7, First page：970, Last page：973, Apr. 2010
  The oxidative addition of selenol, HhfSeH (2, Hhf = 9,10,11,12,14,15-hexahydro-9,10[3′,4′]-furanoanthracenyl) with [Pt(η2-nb)(Ph3P)2] (nb = norbornene) in toluene afforded the corresponding hydrido(selenolato) Pt(II) complex [cis-PtH(SeHhf)(Ph3P)2] (3) as a stable compound. Refluxing a xylene solution of 3 produced two isomers of five-membered selenaplatinacycles 4 in moderate yield as an inseparable mixture. In addition, the molecular structures of HhfSeH 2 and the minor selenaplatinacycle 4a were determined by X-ray crystallography. © 2009 Elsevier B.V. All rights reserved.
  Scientific journal
  DOI：https://doi.org/10.1016/j.jorganchem.2009.11.012
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  DOI ID：10.1016/j.jorganchem.2009.11.012, ISSN：0022-328X, SCOPUS ID：77749314738
• Synthesis, structure, and catalytic activity of bimetallic pt ^II-Ir^III complexes bridged by cyclooctane- 1,2-dithiolato ligands　　　　　　　　　　　　　　　
  Norio Nakata; Masahiro Sakashita; Chizuru Komatsubara; Akihiko Ishii
  European Journal of Inorganic Chemistry, Number：3, First page：447, Last page：453, 2010
  Cationic PtIIIrIII heterobimetallic complexes bridged by cyclooctane-l.,2-dithiolato ligands with [IrCl(μ-Cl)(η5-Cp*)]2 in thf in the presence of AgSbF6. The structures of complexes 5 and 6 were fully characterized, by their NMR spectroscopic data. Moreover, X-ray crystallographic analysis of 5 revealed that the PtS2Ir core exhibits a hinged arrangement, in which the cis-cyclooctane1,2-dithiolate acts as a bridging ligand between the platinum and iridium metals. Complexes 5 and 6 served as a catalyst in the hydrosilylation of terminal alkynes R'CCH (R' = Ph, Bu, CO2Me) with tertiary hydrosilanes such as Et3SiH and Ph3SiH to afford selectively ß-(Z)-vinylsi.lanes 8 in high yields. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/ejic.200900958
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  DOI ID：10.1002/ejic.200900958, ISSN：1434-1948, eISSN：1099-0682, SCOPUS ID：74549170377
• Hydroselenation and carboselenation of electron-deficient alkynes with isolable (Hydrido)(selenolato)platinum(II) complexes and a selenaplatinacycle bearing a triptycene skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Hitomi Kamon; Keiko Murakami; Norio Nakata
  European Journal of Organic Chemistry, Number：9, First page：1653, Last page：1659, 2010
  The reaction of [PtH(SeTrip) (PPh3)2] (Trip = 9-triptycyl) (3) with dimethyl acetylenedicarboxylate (DMAD) or methyl propiolate gave hydroselenation syn adducts. The reaction of [PtH(SeTrip)(dppe)J [dppe = 1,2-bis(diphenylphosphanyl)ethane], which has a stronger phosphane σ-donor ligand than 3, with DMAD gave both syn and anti adducts. The reaction of 3 and DMAD in the presence of PPh3 yielded no adducts. These observations indicate that, in the hydroselenation, the dissociation of a PPh3 ligand from 3 is a key step. The selenaplatinacycle 6, which is a thermal reaction product of 3, reacted with DMAD to give the carboselenation product, 1H-2-benzoselenin 7, which was also formed by the reaction of TripSeH with DMAD. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/ejoc.200901408
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  DOI ID：10.1002/ejoc.200901408, ISSN：1434-193X, eISSN：1099-0690, SCOPUS ID：77949292190
• Thermal reaction of a (hydrido)(selenolato)platinum(ii) complex having a dibenzobarrelenyl group leading to three cyclometalations　　　　　　　　　　　　　　　
  Akihiko Ishii; Yuki Yamaguchi; Norio Nakata
  Dalton Transactions, Volume：39, Number：27, First page：6181, Last page：6183, 2010
  The thermal reaction of a (dibenzobarreleneselenolato)(hydrido)platinum(ii) complex gave two four-membered selenaplatinacycles, one of which is formed by hydroplatination of the Pt-H bond to the etheno bridge and the other is a vinylic C-H bond activation product, and a five-membered selenaplatinacycle formed by an aromatic C-H bond activation. © 2010 The Royal Society of Chemistry.
  Scientific journal
  DOI：https://doi.org/10.1039/c0dt00483a
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  DOI ID：10.1039/c0dt00483a, ISSN：1477-9226, eISSN：1477-9234, SCOPUS ID：77954265690
• Three syntheses of trans-cyclooctane-1,2-dithiol by ring opening of cis-cyclooctene episulfoxide with ammonium thiocyanate followed by reduction and reductions of trans-1,2-di(thiocyanato)cyclooctane and trans-1,2-cyclooctyl trithiocarbonate　　　　　　　　　　　　　　　
  Akihiko Ishii; Aya Ono; Norio Nakata
  Journal of Sulfur Chemistry, Volume：30, Number：3-4, First page：236, Last page：244, Jun. 2009
  Trans-Cyclooctane-1,2-dithiol was synthesized by three methods: (i) ring opening of trans-cyclooctene episulfoxide with NH4SCN in THF followed by a stepwise reduction with diisobutylaluminum hydride (DIBAH) in hexane and then LiAlH4 in ether; (ii) a stepwise reduction of trans-1,2-di(thiocyanato)cyclooctane 11 with DIBAH and then LiAlH4; and (iii) the reduction of trans-1,2-cyclooctyl trithiocarbonate with LiAlH 4 in refluxing ether. The course of reactions of method (i) was investigated in detail.
  Scientific journal
  DOI：https://doi.org/10.1080/17415990902839435
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  DOI ID：10.1080/17415990902839435, ISSN：1741-5993, eISSN：1741-6000, SCOPUS ID：71149085757
• Oxidation and reduction reactions of cis-9,10,11-trithiabicyclo[6.3.0] undecane synthesized by reaction of cis-Cyclooctene with S⁸O　　　　　　　　　　　　　　　
  Akihiko Ishii; Manami Suzuki; Taeko Sone; Norio Nakata
  Phosphorus, Sulfur and Silicon and the Related Elements, Volume：184, Number：5, First page：1184, Last page：1205, May 2009
  cis-Cyclooctene reacted with S8O in refluxing carbon disulfide to give cis-9,10,11-trithiabicyclo[6.3.0]undecane (1,2,3-trithiolane). Oxidation of the 1,2,3-trithiolane with m-chloroperbenzoic acid (MCPBA) or dimethyldioxirane (DMD) yielded the corresponding 1-exo-oxide, 1-endo-oxide, 2-endo-oxide, 2-exo-oxide, 1-endo,3-exo-dioxide, 1-exo,3-exo-dioxide, 1,1,3-exo-trioxide, and 1,1,3,3-tetraoxide, depending on the amount of the oxidants. Formation of another 1,3-dioxide assignable to the 1-endo,3-endo-dioxide was observed in the oxidation of the 1-endo-oxide with MCPBA. Oxidation of the 2-exo-oxide with DMD gave the 1,1,3,3-tetraoxide in low yield. Reduction of the 1,2,3-trithiolane and its trans isomer with LiAlH 4 gave cis- and trans-cyclooctane-1,2-dithiol, respectively, in high yields. Oxidation of the sodium salt of the cis-1,2-dithiol with MCPBA provided the corresponding 1,2,5,6-tetrathiocane in low yield as the only identifiable product. © Taylor & Francis Group, LLC.
  Scientific journal
  DOI：https://doi.org/10.1080/10426500902855232
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  DOI ID：10.1080/10426500902855232, ISSN：1042-6507, eISSN：1563-5325, SCOPUS ID：70349755654
• Reactions of 9-triptyceneselenol with palladium(0) complexes: Unexpected formations of the dinuclear palladium(I) complex [{pd(PPh3)} 2(μ-SeTrip)2] and Five-Membered Selenapalladacycle [Pd(η²(C,Se)-Trip)(dppe)]　　　　　　　　　　　　　　　
  Norio Nakata; Rei Uchiumi; Tomoharu Yoshino; Takashige Ikeda; Hitomi Kamon; Akihiko Ishii
  Organometallics, Volume：28, Number：7, First page：1981, Last page：1984, Apr. 2009
  The oxidative addition reaction of the overcrowded selenol TripSeH (1; Trip = 9-triptycyl) with [Pd(Ph3P)4] in toluene produced a novel dinuclear palladium(I) complex with bridging selenolato ligands, [{Pd(PPh3)}2(μ-SeTrip)2] (2). In contrast, the reaction of 1 with [Pd(dppe)2] in toluene resulted in the formation of the five-memhered selenapalladacycle lPd(η2(C,Se)- Tnp)(dppe)] (3). © 2009 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om900077d
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  DOI ID：10.1021/om900077d, ISSN：0276-7333, SCOPUS ID：65349117584
• Synthesis and crystal structures of the first stable mononuclear dihydrogermyl(hydrido) platinum(II) complexes　　　　　　　　　　　　　　　
  Norio Nakata; Shun Fukazawa; Akihiko Ishii
  Organometallics, Volume：28, Number：2, First page：534, Last page：538, Jan. 2009
  The first stable dihydrogermyl(hydrido) platinum(II) complex cis-(Ph3P)2Pt(H)(GeH2Trip) (2) was synthesized by the oxidative addition reaction of an overcrowded trihydrogermane, TripGeH 3 (1, Trip = 9-triptycyl), with (Ph3P)2Pt(η 2-C2H4) in toluene. The reaction of 1 with (dppe)PtCl2 in the presence of NaBH4 afforded the corresponding hydrido complex (dppe)Pt(H)(GeH2Trip) (3) together with bis(germyl) platinum(II) complex (dppe)Pt(GeH2Trip)2 (4). In addition, the ligand exchange reaction of complex 2 with free Cy 2PCH2CH2PCy2 in toluene resulted in the formation of (dcpe)Pt(H)(GeH2Trip) (5) in moderate yield. The structures of complexes 2-5 were fully determined on the basis of their NMR and IR spectra and elemental analyses. Moreover, the low-temperature X-ray crystallography of 2, 3, and 5 revealed that the platinum center has a distorted square-planar environment, probably due to the Steric requirement of the cis-coordinated phosphine ligands and the bulky 9-triptycyl group on the germanium atom. Furthermore, the thermal rearrangement of bis(germyl) complex 4 in toluene at 60 °C gave digermyl- (hydrido) complex (dppe)Pt(H)[Ge(HTrip) GeH2Trip] (6) in high yield without irreversible reductive elimination of tetrahydrodigermane.© 2009 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om800809n
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  DOI ID：10.1021/om800809n, ISSN：0276-7333, SCOPUS ID：61849136135
• Synthesis and X-ray structural analysis of hydrido(thiolato) platinum(II) complexes　　　　　　　　　　　　　　　
  Norio Nakata; Suzuka Yamamoto; Wataru Hashima; Akihiko Ishii
  Chemistry Letters, Volume：38, Number：5, First page：400, Last page：401, 2009
  The oxidative addition of [Pt(η 2-nb)(PPh 3) 2] with a sterically hindered thiol, TripSH (4, Trip = 9-triptycyl) in toluene afforded cis-hydrido(thiolato) Pt II complex [PtH(STrip)(PPh 3) 2] (5), as thermally and moisture-stable colorless crystals in 91% yield. Complex 5 was fully characterized by 1H, 13C{ 1H}, and 31P{ 1H) NMR and IR spectroscopies, and the molecular structure of 5 was determined by X-ray crystallography. Copyright © 2009 The Chemical Society of Japan.
  Scientific journal
  DOI：https://doi.org/10.1246/cl.2009.400
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  DOI ID：10.1246/cl.2009.400, ISSN：0366-7022, eISSN：1348-0715, SCOPUS ID：67650360823
• Zirconium complex of an [OSSO]-type diphenolate ligand bearing trans-1,2-cyclooctanediylbis(thio) core: Synthesis, structure, and isospecific 1-hexene polymerization　　　　　　　　　　　　　　　
  Akihiko Ishii; Tomoyuki Toda; Norio Nakata; Tsukasa Matsuo
  Journal of the American Chemical Society, Volume：131, Number：38, First page：13566, Last page：13567, 2009
  (Chemical Equation Presented) Six-coordinated dibenzyl Zr complex bearing an [OSSO]-type tetradentate ligand was synthesized, and the structure was fully characterized by NMR spectroscopy and X-ray crystallography. The zirconium complex has C2 symmetry in solution. Owing to an effect of the cyclooctane ring structure, the combination of the zirconium complex and B(C6F5)3 or (Ph3C) [B(C 6F5)4] as the activator exhibited high activity toward polymerization of 1-hexene to yield highly isotactic poly(1-hexene). © 2009 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ja903369q
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  DOI ID：10.1021/ja903369q, ISSN：0002-7863, SCOPUS ID：70349739283
• Reactions of a ditriptycyl-substituted selenoseleninate and related compounds with a platinum(0) complex: Formation of selenaplatinacycle and hydrido selenolato platinum(II) complexes　　　　　　　　　　　　　　　
  Akihiko Ishii; Norio Nakata; Rei Uchiumi; Keiko Murakami
  Angewandte Chemie - International Edition, Volume：47, Number：14, First page：2661, Last page：2664, Mar. 2008
  (Figure Presented) A selenaplatinacycle (see structure 1; red P, blue Pt, greenSe) is formed by the reactions of TripSe(O)SeTrip (Trip = 9-triptycyl) and TripSeOH with [Pt(PPh3)2-(η2-C 2H4)] by intramolecular C-H activation leading to the cyclometalation. The reaction of TripSeSeTrip with [Pt(PPh3) 2-(η2-C2H4)] also provided 1 together with TripSeH, which reacts with [Pt(PPh3) 2(η2-C2H4)] to give the hydrido selenolato platinum(II) complex 2. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.200705336
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  DOI ID：10.1002/anie.200705336, ISSN：1433-7851, SCOPUS ID：53549092263
• Photochemical reaction of silyl-substituted 1,4-disila(dewar-benzene) with isocyanide and phenylacetylene　　　　　　　　　　　　　　　
  Toru Oikawa; Norio Nakata; Takeshi Matsumoto; Yoshio Kabe; Akira Sekiguchi
  Heteroatom Chemistry, Volume：19, Number：1, First page：87, Last page：92, 2008
  The irradiation of silyl-substituted 1,4-disila(Dewar-benzene) 1 with light of wavelength γ > 320 nm in the presence of 2,6- dimethylphenylisocyanide or phenylacetylene produced 1,4-bis(ditert- butylmethylsilyl)-2,3,5,6-tetraethyl- 7- (2, 6-dimethylphenylimino)-1, 4-disilabicyclo [2.2. 1]hepta-2, 5-diene 5 or 1,4-bis(di-tert-butylmethylsilyl)- 2,3,5,6-tetraethyl-1-(2-phenylethynyl)-1,4-disilacyclohexa-2, 5-diene 6, respectively. The molecular structures of 5 and 6 were determined by spectroscopic data and X-ray crystallography. ©2008 Wiley Periodicals, Inc.
  Scientific journal
  DOI：https://doi.org/10.1002/hc.20411
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  DOI ID：10.1002/hc.20411, ISSN：1042-7163, eISSN：1098-1071, SCOPUS ID：38449108807
• 1,3-Digerma-2-gallata- and -indataallenic anions: The first compounds with Ge=Ga or Ge=In double bonds　　　　　　　　　　　　　　　
  Norio Nakata; Rika Izumi; Vladimir Ya Lee; Masaaki Ichinohe; Akira Sekiguchi
  Chemistry Letters, Volume：37, Number：11, First page：1146, Last page：1147, 2008
  The novel allenic anions consisting of two germanium atoms and a gallium or indium atom, 1,3-digerma-2-gallata- and -indataallenic anions, {M = Cr (2), Mo (3), and W (4); Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), have been synthesized by ligand-exchange reactions between [M(CO) 3(CH3CN)3] (M = Cr, Mo, and W) and the kinetically stabilized germabenzene 1 and characterized by 1H and 13C NMR, IR, and UV/Vis spectroscopy. In the 1H and 13C NMR spectra of 2-4, all of the signals for the germabenzene rings were shifted upfield relative to their counterparts in the free germabenzene 1. X-ray crystallographic analysis of 2 and 4 revealed that the germabenzene ligand was nearly planar and was coordinated to the M(CO)3 group (M = Cr, W) in an η6 fashion. The formation of complexes 2-4 from germabenzene 1 should be noted as the application of germaaromatics as 6π-electron ligands toward complexation with Group 6 metals. On the other hand, treatment of 1 with [{RuCp*Cl}4] (Cp* = C 5Me5) in THF afforded a novel η5-germacy- clohexadienido complex of ruthenium - [RuCp*{η5-C 5H5GeTbt(Cl)}] (9) - instead of the expected η6-germabenzene-ruthenium cationic complex [RuCp* {η6-C5H5GeTbt}]Cl (10). Crystallographic structural analysis of 9 showed that the five carbon atoms of the germacyclohexadienido ligand of 9 were coordinated to the Ru center in an η5 fashion. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/chem.200601196
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  DOI ID：10.1002/chem.200601196, ISSN：0947-6539, eISSN：1521-3765, SCOPUS ID：34250786751
• Preparation of 3,3-di-tert-butylthiirane trans-1,2-dioxide and its reaction with a platinum(0) complex to give a (disulfenato)platinum(II) complex: Regioselectivity of the oxidation of a related (sulfenato-thiolato)platinum(II) complex　　　　　　　　　　　　　　　
  Akihiko Ishii; Masayuki Ohishi; Norio Nakata
  European Journal of Inorganic Chemistry, Number：33, First page：5199, Last page：5206, 2007
  A three-membered vic-disulfoxide, 3,3-di-tert-butyldithiirane trans- 1,2-dioxide (8), was synthesized by oxidation of the corresponding dithiirane 1-oxide 15 in high yield. Treatment of 8 and 15 with a platinum(0) complex, , yielded the (disulfenato)PtII complex 18 and the (sulfenato-thiolato)PtII complex 14, respectively, in high yields. Oxidation of the sulfenato-thiolato complex 14 with an acetone solution of dimethyldioxirane (DMD) took place at the sulfenato sulfur atom to yield the (sulfinato-thiolato)PtII complex 19, while the oxidation with CF 3CO3H occurred at the thiolato-sulfur atom leading to the disulfenato complex 18. Oxidation of 14 with MCPBA formed both 18 and 19. The position of oxidation on 14 with DMD was dependent on the acidity of a coexisting acid. Thus, oxidation of 14 with DMD/CF3CO2H provided 18 and that with DMD/PhCO2H gave 19. Oxidation of 14 with an excess amount of DMD yielded the (disulfonato)PtII complex 20. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
  Scientific journal
  DOI：https://doi.org/10.1002/ejic.200700824
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  DOI ID：10.1002/ejic.200700824, ISSN：1434-1948, eISSN：1099-0682, SCOPUS ID：36549015563
• A stable Schrock-type hafnium-silylene complex　　　　　　　　　　　　　　　
  Norio Nakata; Toshiyuki Fujita; Akira Sekiguchi
  Journal of the American Chemical Society, Volume：128, Number：50, First page：16024, Last page：16025, Dec. 2006
  The first stable hafnium-silylene complex, (η-C5H4Et)2(PMe3)Hf=Si(SiMetBu2)2 (6) was obtained in the form of the phosphine adduct as red crystals by the coupling reaction of 1,1-dilithiosilane (1) with 0.9 equiv of (η-C5H4Et)2HfCl2 in dry toluene at -50 °C, followed by treatment with an excess of PMe3 at -50 °C. In the 29Si NMR spectrum of 6, the signal from the silylene ligand is shifted greatly downfield at 295.4 ppm, with a JSiP coupling constant of 15.0 Hz. X-ray crystallographic analysis of 6 revealed that the Si-Hf bond length (2.6515(9) Å) is about 5% shorter than typical Si-Hf single bonds, obviously indicating the double-bond character between the silicon and hafnium atoms. The compound 6 was found to be a Schrock-type silylene complex, a conclusion that was supported by the natural population analysis (NPA) charge distribution for the model complex, (η-C5H4Et)2(PMe3)Hf=Si(SiMe3)2 (8), showing a negative charge on the silicon atom (-0.34). Copyright © 2006 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ja067251d
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  DOI ID：10.1021/ja067251d, ISSN：0002-7863, SCOPUS ID：33845591959
• Dilithium 1,4-disilacyclohexa-2,5-diene-1,4-diide by the reduction of 1,4-disilabicyclo[2.2.0]hexa-2,5-diene: Synthesis and characterization　　　　　　　　　　　　　　　
  Norio Nakata; Toru Oikawa; Takeshi Matsumoto; Yoshio Kabe; Akira Sekiguchi
  Organometallics, Volume：25, Number：25, First page：5850, Last page：5851, Dec. 2006
  The dilithium 1,4-bis(di-tert-butylmethylsilyl)-2,3,5,6-tetraethyl-1,4- disilacyclohexa-2,5-diene-1,4-diide compound 22-·2[Li +(thf)] was prepared by the reduction of 1,4-bis(ditert- butylmethylsilyl)-2,3,5,6-tetraethyl-1,4-disilabicyclo[2.2.0]-hexa-2,5-diene (1) with lithium in THF. 22-·2[Li+(thf)] has a boat conformation of its six-membered ring with a folding angle of 124.0°. © 2006 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om0609261
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  DOI ID：10.1021/om0609261, ISSN：0276-7333, SCOPUS ID：33845899433
• Synthesis and characterization of two isomers of 14π-electron germaaromatics: Kinetically stabilized 9-germaanthracene and 9-germaphenanthrene　　　　　　　　　　　　　　　
  Takahiro Sasamori; Koji Inamura; Wataru Hoshino; Norio Nakata; Yoshiyuki Mizuhata; Yasuaki Watanabe; Yukio Furukawa; Norihiro Tokitoh
  Organometallics, Volume：25, Number：15, First page：3533, Last page：3536, Jul. 2006
  The first stable 9-germaanthracene and 9-germaphenanthrene were successfully synthesized by taking advantage of kinetic stabilization utilizing effective steric protection groups, Tbt and Bbt groups (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Bbt = 2,6-bis[bis(trimethylsilyl)methylJ4-[tris(trimethylsilyl)methyl]phenyl). The similarities and differences of the structures and properties between the two isomers of germaaromatics are discussed. © 2006 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om060371+
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  DOI ID：10.1021/om060371+, ISSN：0276-7333, SCOPUS ID：33746378641
• A stable silaborene: Synthesis and characterization　　　　　　　　　　　　　　　
  Norio Nakata; Akira Sekiguchi
  Journal of the American Chemical Society, Volume：128, Number：2, First page：422, Last page：423, Jan. 2006
  A stable silicon-boron doubly bonded compound, silaborene (2), was synthesized by the reaction of 1,1-dilithiosilane (1) with dichloro(2,2,6,6-tetramethylpiperidino)borane in toluene. The X-ray crystallographic analysis of 2 revealed that the Si=B<- resonance structure. Copyright © 2006 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ja0570741
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  DOI ID：10.1021/ja0570741, ISSN：0002-7863, SCOPUS ID：31544433734
• Silyl-substituted 1,4-disila(Dewar benzene): New synthesis and unexpected insertion of CO into the Si-Si bond to form a disilyl ketone　　　　　　　　　　　　　　　
  Norio Nakata; Toru Oikawa; Takeshi Matsumoto; Yoshio Kabe; Akira Sekiguchi
  Organometallics, Volume：24, Number：14, First page：3368, Last page：3370, Jul. 2005
  The silyl-substituted 1,4-disila(Dewar benzene) (1) was synthesized by the reduction of the corresponding dichloride 2 with 2.2 equiv of KC8 in THF. The irradiation of 1 with light of wavelength λ > 320 nm in THF under a CO atmosphere produced the cyclic disilyl ketone 3 by the insertion of CO into the central Si-Si bond, whereas the photolysis of 1 in cyclohexane-d12 afforded the silyl-substituted 2,5-disilabenzvalene 4 by intramolecular isomerization. © 2005 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/om050261n
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  DOI ID：10.1021/om050261n, ISSN：0276-7333, SCOPUS ID：22444434578
• Reaction of dilithiosilane R2SiLi2 and dilithiogermane R2GeLi2 (R = SiMetBu 2) with MesBCl2 (Mes = 2,4,6-trimethylphenyl): Evidence for the formation of silaborene R2Si=BMes and germaborene R 2Ge=BMes　　　　　　　　　　　　　　　
  Norio Nakata; Rika Izumi; Vladimir Ya Lee; Masaaki Ichinohe; Akira Sekiguchi
  Chemistry Letters, Volume：34, Number：4, First page：582, Last page：583, Apr. 2005
  1,1-Dilithiosilane and -germane, R2SiLi2 and R 2GeLi2 (R = SiMetBu2) reacted with MesBCl2 to give the unexpected seven-membered ring products, [1,3,2|oxasila- and -germaborepanes, through the intermediate formation of >Si=B- and >Ge=B- doubly bonded species. Copyright © 2005 The Chemical Society of Japan.
  Scientific journal
  DOI：https://doi.org/10.1246/cl.2005.582
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  DOI ID：10.1246/cl.2005.582, ISSN：0366-7022, SCOPUS ID：21644439157
• 1,3-Disila-2-gallata- and -indataallenic Anions [>Si- ^..M-^..Si<]^-·Li⁺ (M = Ga, In): Compounds Featuring Double Bonds between Elements of Groups 13 and 14　　　　　　　　　　　　　　　
  Norio Nakata; Rika Izumi; Vladimir Ya Lee; Masaaki Ichinohe; Akira Sekiguchi
  Journal of the American Chemical Society, Volume：126, Number：16, First page：5058, Last page：5059, Apr. 2004
  The first compounds containing Si=Ga or Si=In double bonds, 1,3-disila-2-gallata- (2-) and -indataallenic anions (3-), were obtained in the form of lithium salts as dark red crystals by the reaction of bis(di-tert-butylmethylsilyl)dilithiosilane 1 with GaCl3 or InCl3. X-ray crystallographic analysis of 2-·[Li(thf)4]+ and 3-·[Li(thf)4]+ showed that the >Si×M×Si< frameworks (M = Ga, In) are not linear and the two Si=M bond lengths are about 9% shorter than typical Si-M single bonds. In the 29Si NMR spectra, the signals of the terminal Si atoms in 2- and 3- are greatly shifted upfield (2-: -79.9; 3-: -77.6 ppm). The NPA charge distribution for the model compound, [(Me3Si)2Si×Ga×Si(SiMe3)2]- (4-) showed a large part of the negative charge localizing on the two terminal silicon atoms (-0.736 and -0.729). In addition, 2-·[Li(thf)4]+ reacted with MeI to give the corresponding iodogallane 5 nearly quantitatively. This result confirms that the allenic [>Si×M×SiSi<]- fragments are highly polarized. Copyright © 2003 American Chemical Society.
  Scientific journal
  DOI：https://doi.org/10.1021/ja040001h
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=1942425158&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=1942425158&origin=inward
  DOI ID：10.1021/ja040001h, ISSN：0002-7863, SCOPUS ID：1942425158
• Reaction of a stable germabenzene with chalcogens: Synthesis and structure of a novel germanium analog of pentathiepane, 1,2,3,4,5,6-pentathiagermepane　　　　　　　　　　　　　　　
  Norio Nakata; Nobuhiro Takeda; Norihiro Tokitoh
  Journal of Organometallic Chemistry, Volume：672, Number：1-2, First page：66, Last page：71, Apr. 2003
  Treatment of a germabenzene (4) bearing a Tbt group (Tbt=2,4,6-tris[bis(trimethylsilyl)methyl]phenyl) with elemental sulfur gave a 1,2,3,4-trithiagermolane (5) together with a novel 1,2,3,4,5,6-pentathiagermepane (6), which is the germanium analog of pentathiepane. On the other hand, the reaction of 4 with elemental selenium gave only 1,2,3,4-triselenagermolane (7). All the newly obtained polychalcogenides containing a germanium atom were characterized by NMR spectroscopy and elemental analysis. The molecular structures of 5 and 6 were determined by X-ray crystallographic analysis. In addition, the thermolyses of 5 and 6 were examined. © 2003 Elsevier Science B.V. All rights reserved.
  Scientific journal
  DOI：https://doi.org/10.1016/S0022-328X(03)00141-4
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0037437221&origin=inward
  DOI ID：10.1016/S0022-328X(03)00141-4, ISSN：0022-328X, SCOPUS ID：0037437221
• Synthesis and properties of the first stable neutral germaaromatic compound, 2-{2,4,6-Tris-[bis(trimethylsilyl)methyl]phenyl}-2-germanaphthalene　　　　　　　　　　　　　　　
  Norio Nakata; Nobuhiro Takeda; Norihiro Tokitoh
  Organometallics, Volume：22, Number：3, First page：481, Last page：489, Feb. 2003
  The first stable neutral germaaromatic compound, 2-germanaphthalene 1a, was synthesized by taking advantage of an extremely bulky and efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt). The molecular structure and aromaticity of 1a were discussed on the basis of its NMR, UV-vis, and Raman spectra, X-ray crystallographic analysis, and theoretical calculations. All the 1H and 13C NMR chemical shifts of the 2-germanaphthalene ring of 1a were in good agreement with the calculated values for 2-germanaphthalene and 2-phenyl-2-germanaphthalene. The patterns of UV-vis and Raman spectra of 1a were similar to those of naphthalene, although the shift to longer wavelength (in the UV-vis spectrum) and smaller wavenumber (in the Raman spectrum) resulting from the replacement of carbon with germanium were observed. X-ray crystallographic analysis of 1a revealed that the 2-germanaphthalene ring was almost planar and perpendicular to the benzene ring of the Tbt group. These experimental results indicate the delocalization of π-electrons in the 2-germanaphthalene ring of 1a. Theoretical calculations (NICS(1), Λ, and ASEisom) also indicated the ring current effects and aromatic stabilization of 2-germanaphthalene. 2-Germanaphthalene 1a reacted as a Ge-C double-bond compound (germene) with water, t-BuLi, mesitonitrile oxide, 2,3-dimethyl-1,3-butadiene, and some elemental chalcogens to give the corresponding adducts.
  Scientific journal
  DOI：https://doi.org/10.1021/om020879m
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0037415305&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0037415305&origin=inward
  DOI ID：10.1021/om020879m, ISSN：0276-7333, SCOPUS ID：0037415305
• η⁶-Germabenzene complexes of chromium and molybdenum　　　　　　　　　　　　　　　
  Norio Nakata; Nobuhiro Takeda; Norihiro Tokitoh
  Angewandte Chemie - International Edition, Volume：42, Number：1, First page：115, Last page：117, Jan. 2003
  η6 Bonding characteristics are exhibited by stable germabenzene complexes that are stabilized with the extremely bulky 2,4,6-tris[bis(trimethylsilyl) methyl]phenyl ligand. The ring system coordinates to transition-metal centers (M = Cr, Mo; see picture) to give the first evidence of the aromatic character in germabenzene complexes, from the standpoint of their chemical reactivity.
  Scientific journal
  DOI：https://doi.org/10.1002/anie.200390038
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0037414919&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0037414919&origin=inward
  DOI ID：10.1002/anie.200390038, ISSN：1433-7851, SCOPUS ID：0037414919
• Reactions of 2-germanaphthalene with elemental sulfur and selenium: Synthesis of novel cyclic polychalcogenides containing a germanium, trichalcogenagermolanes　　　　　　　　　　　　　　　
  Norio Nakata; Nobuhiro Takeda; Norihiro Tokitoh
  Chemistry Letters, Number：8, First page：818, Last page：819, Aug. 2002
  Novel five-membered cyclic trichalcogenides containing a germanium atom were synthesized by the reactions of a kinetically stabilized 2-germanaphthalene with elemental sulfur and selenium, and the molecular structure of the triselenide was determined by X-ray crystallographic analysis.
  Scientific journal
  DOI：https://doi.org/10.1246/cl.2002.818
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0037025506&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0037025506&origin=inward
  DOI ID：10.1246/cl.2002.818, ISSN：0366-7022, SCOPUS ID：0037025506
• Synthesis and properties of the first stable germabenzene　　　　　　　　　　　　　　　
  Norio Nakata; Nobuhiro Takeda; Norihiro Tokitoh
  Journal of the American Chemical Society, Volume：124, Number：24, First page：6914, Last page：6920, Jun. 2002
  The first stable germabenzene (1a) bearing an efficient steric protection group, 2,4,6-tris[bis-(trimethylsilyl)methyl]phenyl, was successfully synthesized by the reaction of the corresponding chlorogermane (4) with lithium diisopropylamide in THF. The molecular structure and aromaticity of 1a were discussed on the basis of its NMR, UV-vis, and Raman spectra, X-ray crystallographic analysis, and theoretical calculations. All 1H and 13C NMR chemical shifts of the germabenzene ring of 1a were in good agreement with those calculated. UV-vis and Raman spectra of 1a showed patterns similar to those of benzene, suggesting the structural similarity between germabenzene and benzene. X-ray crystallographic analysis of 1a revealed that the germabenzene ring was almost planar, indicating the delocalization of π-electrons. Theoretical calculations (NICS(1) and ASEsom) also indicated the ring current effects and aromatic stabilization of the germabenzene. While germabenzene la reacted as a Ge-C double-bond compound (germene) with mesitonitrile oxide and 2,3-dimethyl-1,3-butadiene, 1a also reacted as a 1 -germabuta-1,3-diene with C-C double- and triple-bond compounds. Furthermore, 1a reacted with water and MeOH to give both 1, 2- and 1, 4-adducts.
  Scientific journal
  DOI：https://doi.org/10.1021/ja0262941
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0037134939&origin=inward
  DOI ID：10.1021/ja0262941, ISSN：0002-7863, PubMed ID：12059214, SCOPUS ID：0037134939
• Synthesis and characterization of an extremely hindered tetraaryl-substituted digermene and its unique properties in the solid state and in solution　　　　　　　　　　　　　　　
  Norihiro Tokitoh; Kuniyuki Kishikawa; Renji Okazaki; Takahiro Sasamori; Norio Nakata; Nobuhiro Takeda
  Polyhedron, Volume：21, Number：5-6, First page：563, Last page：577, Mar. 2002
  An extremely hindered digermene (E)-Tbt(Mes)Ge=Ge(Mes)Tbt (1; Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Mes = mesityl) was synthesized. X-ray crystallographic analysis of the hexane solvated single crystal [1·0.5hexane] revealed that 1 has an extremely long germanium-germanium double bond [2.416(2) Å] as that of a carbon-substituted digermene. The temperature-dependent change of UV-Vis absorption of digermene 1 in solution indicated the quantitative interconversion between 1 and the corresponding germylene Tbt(Mes)Ge: (3). The thermodynamic parameters (ΔH = 14.7 ± 0.2 kcal mol-1 and ΔS = 42.4 ± 0.8 cal mol-1 deg-1) for the dissociation of digermene 1 to germylene 3 were obtained from temperature dependence of the absorption of 1. Since the reactivity of germylene 3 is much higher than that of digermene 1, almost all the intermolecular reactions of 1 in solution proceeded via dissociated 3. For instance, the reaction of 1 with oxygen in solution resulted in a non-stereospecific formation of the cis- and trans-1,3,2,4-dioxadigermetanes 11 and 7 via the initial formation of germanone 12 derived from oxygenation of the dissociated germylene 3. In case of the oxidation in the solid state, however, digermene 1 reacted with O2 without dissociation to give the corresponding trans-substituted 1,3,2,4-dioxadigermetane stereospecifically. The reaction of digermene 1 with W(CO)5(THF) was also examined to give the corresponding terminal tungsten complex of the dissociated germylene 3, i.e. Tbt(Mes)Ge=W(CO)5 (23), as a marginally stable orange yellow paste. © 2002 Published by Elsevier Science Ltd.
  International conference proceedings
  DOI：https://doi.org/10.1016/S0277-5387(01)01035-X
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0037088222&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0037088222&origin=inward
  DOI ID：10.1016/S0277-5387(01)01035-X, ISSN：0277-5387, SCOPUS ID：0037088222
• Synthesis and structure of a kinetically stabilized 2-germanaphthalene: The first stable neutral germaaromatic compound　　　　　　　　　　　　　　　
  Norio Nakata; Nobuhiro Takeda; Norihiro Tokitoh
  Organometallics, Volume：20, Number：26, First page：5507, Last page：5509, Dec. 2001
  The first stable neutral germaaromatic compound, i.e., the 2-germanaphthalene 1a bearing an efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt), was successfully synthesized by the reaction of the corresponding bromogermane 4 with lithium diisopropylamide. The molecular structure and aromaticity of 1a were discussed on the basis of its NMR, UV-vis, and Raman spectra, X-ray crystallographic analysis, and theoretical calculations.
  Scientific journal
  DOI：https://doi.org/10.1021/om010881y
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0035945422&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0035945422&origin=inward
  DOI ID：10.1021/om010881y, ISSN：0276-7333, SCOPUS ID：0035945422

• Synthesis and photophysical property of 1-chalcogeno-1,3-butadiene derivatives and the related compounds incorporated in a dibenzobarrelene skeleton　　　　　　　　　　　　　　　
  Akihiko Ishii; Norio Nakata
  Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry, Volume：76, Number：10, First page：1042, Last page：1054, 2018
  In recent years, luminescent organic compounds including group 13-16 elements have been extensively studied from the viewpoints of applications for electronic devices and chemical sensors, in which the group 13 - 16 elements play an important role by providing a perturbation to the photophysical property of original hydrocarbons. We have developed dibenzobarrelene-incorporated 1-chalcogeno-1,3-butaidiene derivatives being fluorescent with high efficiency, which are synthesized by two methods; ( 1) the reaction of thio-or selenometallacycles with dimethyl acetylenedicarboxylate or (2) the intramolecular cycloaddition between (9-anthryl)chalcogeno and arylalkynyl groups connected by a (Z)-alkenyl group. The latter method (2) are applied to the syntheses of benzobarrelene analogues, 1-aza-1,3-butadiene analogues by cyano-Diels-Alder reaction, thiophene-fused analogues, and derivatives having π-donor and π-acceptor substituents that luminesce in the near-infrared region. In addition, we have succeeded in the synthesis of carbon and silicon analogues utilizing the intramolecular cycloaddition. In this paper, we describe the syntheses of the luminescent compounds in details with comparing their relevant and characteristic photophysical properties.
  Book review
  DOI：https://doi.org/10.5059/yukigoseikyokaishi.76.1042
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85055051317&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85055051317&origin=inward
  DOI ID：10.5059/yukigoseikyokaishi.76.1042, ISSN：0037-9980, SCOPUS ID：85055051317
• Macromol. Rapid Commun. 12/2016　　　　　　　　　　　　　　　
  Yusuke Saito; Norio Nakata; Akihiko Ishii
  Macromolecular Rapid Communications, Volume：37, Number：12, First page：1008, 01 Jun. 2016
  Report scientific journal
  DOI：https://doi.org/10.1002/marc.201670051
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84975109792&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84975109792&origin=inward
  DOI ID：10.1002/marc.201670051, ISSN：1022-1336, eISSN：1521-3927, SCOPUS ID：84975109792
• Isospecific Polymerization of α-Olefins Catalyzed by Transition-metal Catalysts Supported by Cycloalkane-fused[OSSO]-type Tetradentate Ligand　　　　　　　　　　　　　　　
  石井 昭彦; 中田 憲男
  Volume：58, Number：1, First page：2, Last page：7, Jan. 2016
  Japanese
  ISSN：0559-8958, CiNii Articles ID：40020732352, CiNii Books ID：AN00117719
• Recent advances in the chemistry of Group 4 metal complexes incorporating [OSSO]-type bis(phenolato) ligands as post-metallocene catalysts　　　　　　　　　　　　　　　
  Norio Nakata; Tomoyuki Toda; Akihiko Ishii
  Polymer Chemistry, Volume：2, Number：8, First page：1597, Last page：1610, Aug. 2011
  Several recent efforts concerning post-metallocene Group 4 metal complexes incorporating mixed donor [OSSO]-type tetradentate bis(phenolato) ligands are reviewed. These [OSSO]-type ligands can be mainly classified as 5-5-5, 5-6-5 and 6-5-6 arrays of chelate rings toward central metals. As the main topics are described the design and unique coordination chemistry of the [OSSO]-type ligands and catalytic activities of the resultant titanium, zirconium, and hafnium complexes as single-site catalysts for polymerizations and copolymerizations of olefins. © 2011 The Royal Society of Chemistry.
  Book review
  DOI：https://doi.org/10.1039/c1py00058f
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=79960303151&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=79960303151&origin=inward
  DOI ID：10.1039/c1py00058f, ISSN：1759-9954, eISSN：1759-9962, SCOPUS ID：79960303151
• Study on the effective and selective synthetic reaction with transition metal　　　　　　　　　　　　　　　
  石井 昭彦; 中田 憲男; 芦田 彪; 加藤 淳一; 新井 輝明; 森 さやか
  Number：2, First page：23, Last page：25, 2009
  The thermal reaction of a (dibenzobarreleneselenolato)(hydrido)platinum(II) complex gave twofour-membered selenaplatinacycles, one of which is formed by hydroplatination of the Pt-H bond to the etheno bridge and the other is a vinylic C-H bond activation. The reaction mechanism for the cyclometalation is investigated.
  Japanese
  ISSN：1883-8278, CiNii Articles ID：120002354108, CiNii Books ID：AA12486867
• Study on the effective and selective synthetic reaction with transition metal catalysts
  石井 昭彦; 中田 憲男; 芦田 彪; 加藤 淳一; 新井 輝明; 森 さやか
  Report of Comprehensive Open Innovation Center, Saitama University, Number：1, First page：30, Last page：32, 2008
  The oxidative addition of [Pt(2-nb)(PPh3)2] with a sterically hindered thiol TripSH (Trip = 9-triptycyl) in toluene afforded cis-hydrido(thiolato) Pt(II) complex PtH(Strip)(PPh3)2 as thermally and moisture stable colorless crystals in 91% yield. The thermal reaction of PtH(Strip)(PPh3)2 gave the corresponding thiaplatinacycle. The first stable dihydrogermyl(hydrido) platinum(II) complex PtH(GeH2Trip)(Ph3P)2 was synthesized by the oxidative addition reaction of TripGeH3 with Pt( 2-C2H4)(Ph3P)2 in toluene. The reaction of TripGeH3 with (dppe)PtCl2 in the presence of NaBH4 afforded the corresponding hydrido complex PtH(GeH2Trip)(dppe) together with bis(germyl) platinum(II) complex Pt(GeH2Trip)2(dppe). The ligand exchange reaction of PtH(GeH2Trip)(Ph3P)2 with Cy2PCH2CH2PCy2 (DCPE) in toluene resulted in the formation of PtH(GeH2Trip)(dcpe) in the moderate yield. Thermal rearrangement of Pt(GeH2Trip)2(dppe) in toluene at 60 ˚C gave digermyl(hydrido) complex PtH[Ge(Htrip)GeH2Trip](dppe) in high yield.
  Japanese
  ISSN：1883-8278, CiNii Articles ID：120001493933

• May 2017 - Present
• Oct. 2013 - Present
• Feb. 2012 - Present
• Jun. 2008 - Present
• Dec. 2004 - Present
• Sep. 2000 - Present
• Oct. 1997 - Present

• Coordination chemistry of stronger sigma-donating N-heterocyclic silylenes than carbenes　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), 01 Apr. 2022 - 31 Mar. 2025
  Saitama University
  Grant amount(Total)：4290000, Direct funding：3300000, Indirect funding：990000
  Grant number：22K05138
• Development of precise synthetic method for paraffinic fuel precursors by post-metallocene catalysts　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), 01 Apr. 2017 - 31 Mar. 2020
  Nakata Norio, Saitama University
  Grant amount(Total)：4810000, Direct funding：3700000, Indirect funding：1110000
  In this research project, we aimed to develop a precise synthetic methodology for the vinylidene dimer of 1-hexene, which can be used as precursors of alternative jet fuels. Upon activation of arious aryl-substituted [OSSO]-type zirconium complexes with 100-300 equivalents of dried modified-methylaluminoxane as a co-catalyst, the oligomerization of 1-hexene were perfectly proceeded to give the corresponding vinylidene-selective dimer as a main product. The TOF values of these reactions were found to be quite higher than those of conventional metallocene catalysts.
  Grant number：17K05771
• ヒドリドシリレンを感応性化学種とする触媒機能の設計・開発　　　　　　　　　　　　　　　
  01 Apr. 2015 - 31 Mar. 2017
  Grant amount(Total)：5200000, Direct funding：4000000, Indirect funding：1200000
  Grant number：15H00919
• Development and design of [OSSO]-type catalysts for precise polymerization of versatile alfa-olefins　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), 01 Apr. 2013 - 31 Mar. 2016
  Nakata Norio, Saitama University
  Grant amount(Total)：5330000, Direct funding：4100000, Indirect funding：1230000
  In order to realize precise polymerization of versatile alfa-olefins such as propylene and styrene, novel [OSSO]-type bis(phenolate) ligands based on a trans-1,2-cyclooctanediyl platform and their zircoium complexes were developed. As a result, upon activation with dMAO (dried methylaluminoxane), the complex 4 was found to promote highly isospecific styrene polymerizations ([mm] = 97.5-99%) with high molecular weights up to 181,000 g mmol-1. When the Dmp-substituted pre-catalyst 5/dMAO system was used, the highest activity over 7,700 g mmol(5)-1 h-1 was recorded involving the formation of precisely isospecific polystyrenes of [mm] more than 99%.
  Grant number：25410035
• 生体内の硫化水素を可視化するON-OFF型蛍光プローブの開発　　　　　　　　　　　　　　　
  2014 - 2015
• 炭素－硫黄結合ならびに酸素－水素結合の同時活性化を鍵とする新規分子変換反応の開発　　　　　　　　　　　　　　　
  01 Apr. 2011 - 31 Mar. 2013
  Grant amount(Total)：7020000, Direct funding：5400000, Indirect funding：1620000
  Grant number：23105508
• Development of ultimate post-metallocene catalyst realizing high activity, high stereoselectivity, and living polymerization　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Grant-in-Aid for Young Scientists (B), 2011 - 2012
  NAKATA Norio, Saitama University
  Grant amount(Total)：4680000, Direct funding：3600000, Indirect funding：1080000
  In order to realize high active, high stereoselective, and living polymerization of α-olefin, a series of novel [OSSO]-type ligands and their Group 4 and 5 transition metal complexes were developed. As a result, dMAO-activated zirconium(IV), hafnium(IV), titanium(III) and (IV), and tantalum(V) complexes having the [OSSO]-type ligand could be catalyzed the polymerization of1-hexene to produce perfectly isotactic polymers. In the presence of dMAO as an activator, especially, a dichloro zirconium(IV) pre-catalyst incorporating with the [OSSO]-type ligand was found to promote1-hexene polymerizations giving completely isotactic polymer with excellent activity of 17,300 g・mmol^<-1>・h<1>.
  Grant number：23750034
• Study on the Reaction Mechanism of the Reaction of Isolable Hydrido-chalcogenolato Platinum Complexes with Alkynes　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), 2009 - 2011
  ISHII Akihiko; NAKATA Norio, Saitama University
  Grant amount(Total)：4940000, Direct funding：3800000, Indirect funding：1140000
  The hydroselenation of hydrido-selenolato Pt(II) complexes with alkynes was studied. On the basis of the results employing the complexes having a 9-triptycyl group on the selenium and triphenylphosphine or 1,2-(diphenylphosphino)ethane as the phosphorus ligand, it was revealed that the dissociation of a phosphorus ligand is essential in the initial stage. It is also discovered that the complex having triphenyl phosphite ligands reacts with phenylacetylene to yield the corresponding selenaplatinacycle and styrene.
  Grant number：21550035
• 強発光性含カルコゲン複素環化合物の開発と発光材料への応用　　　　　　　　　　　　　　　
  2009 - 2009
  Principal investigator
• 4族遷移金属-シリレン錯体の創製とそれを触媒とする新規重合反応の開発　　　　　　　　　　　　　　　
  2007 - 2008
  Grant amount(Total)：3600000, Direct funding：3600000
  Grant number：18750026
• セレナメタラサイクルの創製と新合成反応への展開　　　　　　　　　　　　　　　
  2007 - 2007
  Grant amount(Total)：2500000, Direct funding：2500000
  Grant number：19027014