A5078901618- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Crystallography and molecular interactions
- Metal-Catalyzed Oxygenation Mechanisms
- Metal complexes synthesis and properties
- Magnetism in coordination complexes
- Organometallic Complex Synthesis and Catalysis
- Polyoxometalates: Synthesis and Applications
- Porphyrin and Phthalocyanine Chemistry
- Metal-Organic Frameworks: Synthesis and Applications
- Oxidative Organic Chemistry Reactions
- Chemical Synthesis and Reactions
- Machine Learning in Materials Science
- Lanthanide and Transition Metal Complexes
- Mesoporous Materials and Catalysis
- Vanadium and Halogenation Chemistry
- Carbon dioxide utilization in catalysis
- Synthetic Organic Chemistry Methods
- Asymmetric Hydrogenation and Catalysis
- Synthesis and characterization of novel inorganic/organometallic compounds
- Catalytic C–H Functionalization Methods
- Catalytic Processes in Materials Science
- Catalytic Cross-Coupling Reactions
- Covalent Organic Framework Applications
- Cyclopropane Reaction Mechanisms
Kanagawa University
2016-2025
Japan Science and Technology Agency
2006-2023
Faculty (United Kingdom)
2019-2020
Engineering (Italy)
2019-2020
Material (Belgium)
2013-2014
Hitachi (Japan)
1998-2013
Ibaraki National College of Technology
1998-2013
Komatsu (Japan)
2013
Kao Corporation (Japan)
2010
Tokyo Institute of Technology
1998-2009
Epoxides are an important class of industrial chemicals that have been used as chemical intermediates. Catalytic epoxidation olefins affords interesting production technology. We found a widely usable green route to the epoxides: A silicotungstate compound, [gamma-SiW10O34(H2O)2]4-, is synthesized by protonation divacant, lacunary, Keggin-type polyoxometalate [gamma-SiW10O36]8- and exhibits high catalytic performance for various olefins, including propylene, with hydrogen peroxide (H2O2)...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFixation of atmospheric carbon dioxide by a series hydroxo complexes divalent metal ions and the implication for catalytic role ion in carbonic anhydrase. Synthesis, characterization, molecular structure [LM(OH)]n (n = 1 or 2) LM(.mu.-CO3)ML (M(II) Mn, Fe, Co, Ni, Cu, Zn; L HB(3,5-iso-Pr2pz)3)Nobumasa Kitajima, Shiro Hikichi, Masako Tanaka, Yoshihiko MorookaCite this: J. Am. Chem. Soc. 1993, 115, 13, 5496–5508Publication Date (Print):June 1,...
The tetra-n-butylammonium (TBA) salt of the divacant Keggin-type polyoxometalate [TBA](4)[gamma-SiW(10)O(34)(H(2)O)(2)] (I) catalyzes oxygen-transfer reactions olefins, allylic alcohols, and sulfides with 30 % aqueous hydrogen peroxide. negative Hammett rho(+) (-0.99) for competitive oxidation p-substituted styrenes low value (nucleophilic oxidation)/(total oxidation), X(SO)=0.04, I-catalyzed thianthrene 5-oxide (SSO) reveals that a strongly electrophilic oxidant species is formed on I....
Rhodium−diene complexes with the TpiPr ligand, TpiPrRh(diene) (TpiPr = hydridotris(3,5-diisopropylpyrazolyl)borate; diene 1,5-cyclooctadiene (cod) (1), norbornadiene (nbd) (2)), are prepared by treatment of [Rh(μ-Cl)(diene)]2 KTpiPr or TlTpiPr. The structure 1, characterized X-ray crystallography, contains κ2-coordinated and its central Rh atom adopts a square-planar geometry, whereas unit cell 2 two independent molecules: ligand similar to 1 trigonal-bipyramidal one κ3-coordinated ligand....
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Monomeric Side-On Peroxo Manganese(III) Complex: Mn(O2)(3,5-iPr2pzH)(HB(3,5-iPr2pz)3)Nobumasa Kitajima, Hidehito Komatsuzaki, Shiro Hikichi, Masahisa Osawa, and Yoshihiko Moro-okaCite this: J. Am. Chem. Soc. 1994, 116, 25, 11596–11597Publication Date (Print):December 1, 1994Publication History Published online1 May 2002Published inissue 1 December...
Abstract Reaction of O 2 with a high‐spin mononuclear iron(II) complex supported by five‐azole donor set yields the corresponding non‐heme iron(III)–superoxo species, which was characterized UV/Vis spectroscopy and resonance Raman spectroscopy. 1 H NMR analysis reveals diamagnetic nature superoxo arising from antiferromagnetic coupling between spins on low‐spin iron(III) superoxide. This species reacts H‐atom donating reagents to give iron(III)–hydroperoxo showing characteristic UV/Vis,...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFirst Synthesis and Structural Characterization of Dinuclear M(III) Bis(μ-oxo) Complexes Nickel Cobalt with Hydrotris(pyrazolyl)borate Ligand†Shiro Hikichi, Michito Yoshizawa, Yasuyuki Sasakura, Munetaka Akita, Yoshihiko Moro-okaView Author Information Research Laboratory Resources Utilization Tokyo Institute Technology, 4259 Nagatsuta Midori-ku, Yokohama 226-8503, Japan Cite this: J. Am. Chem. Soc. 1998, 120, 40, 10567–10568Publication Date...
Reaction of the dinuclear MII–bis(μ-hydroxo) complexes nickel and cobalt, [{MII(TpR)}2(μ-OH)2] (M=Ni; 3Ni, M=Co: 3Co), with one equivalent H2O2 yields corresponding MIII–bis(μ-oxo) complexes, [{MIII(TpR)}2(μ-O)2] 2Ni, 2Co). The employment a series Tp (Tp=hydrotris(3,5-dimethyl-4-X-1-pyrazolyl)borate; X=Me, H, Br) as metal supporting ligand makes it possible to isolate structurally characterize thermally unstable 2Ni 2Co. Both starting (3Ni 3Co) resulting (2Ni 2Co) contain five-coordinate...
A novel titanium-substituted silicotungstate cluster of [{gamma-SiTi2W10O36(OH)2}2(mu-O)2]8- (1) is synthesized by the introduction titanium(IV) ions into a divacant lacunary gamma-Keggin-type [gamma-SiW10O36]8-. This polyoxometalate, 1, exhibits dimeric structure. One half gamma-Keggin fragment 1 contains dinuclear titanium center bridged two hydroxo groups, and resulting Ti2(mu-OH)2 core connects to other paired subunit through Ti-O-Ti linkages. The reacts with MeOH form corresponding...
Nickel complexes with hydrotris(pyrazolyl)borate ( = Tp(R)) ligands catalyze alkane oxidation organic peroxide meta-Cl-C(6)H(4)C([double bond, length as m-dash]O)OOH mCPBA). The electronic and steric hindrance properties of Tp(R) affect the catalyses. complex an electron-withdrawing group containing a less-hindered ligand, that is, Tp(Me2,Br), exhibits higher alcohol selectivity. Higher selectivity for secondary over tertiary alcohols upon methylcyclohexane indicates oxygen atom transfer...
The nickel(II)-acylperoxo complex [Ni(Tp(CF3Me))(κ(2)-mCPBA)] (1(CF3Me)) [Tp(CF3Me) = hydrotris(3-trifluoromethyl-5-methylpyrazolyl)borate, mCPBA m-chloroperbenzoate] was isolated and fully characterized. electrophilic oxygenation ability of 1(CF3Me) toward sulfides olefins confirmed. Michaelis-Menten-type behavior thioanisole indicates the existence a pre-equilibrium substrate association in reaction. In addition, retains H-atom abstraction for hydrocarbons with activated methylene C-H...
Aliphatic C−H bond oxygenation is achieved by Co(II)−peroxo species. The dinuclear Co(II)−μ-peroxo complex, {Co[HB(3,5-Pri2pz)3]}2(μ-O2) (2), yielded reaction of the bis(μ-hydroxo)−Co(II) {Co(OH)[HB(3,5-Pri2pz)3]}2 (1), with an equimolar amount H2O2. Spontaneous decomposition μ-peroxo complex 2 yields a mono-oxygenated μ-alkoxo-μ-hydroxo in which one six 3-isopropyl methine carbon atoms oxygenated and resulting alkoxo ligand bridges two Co(II) centers. In contrast, presence excess H2O2...
A series of hydrocarbyl complexes supported only by hydrotris(pyrazolyl)borato ligands (TpR' = 3,5-diisopropylpyrazolyl (TpiPr2) and 3,4,5-trimethylpyrazolyl derivatives (TpMe3)), TpR'M−R (M/R/R' Ni/η3-allyl/iPr2 (2iPr2Ni), Co/η3-allyl/iPr2 (2iPr2Co), Fe/η1-allyl/iPr2 (2iPr2Fe), Ni/η3-prenyl/iPr2 (3iPr2Ni), Co/η1-p-methylbenzyl/iPr2 (4iPr2Co), Fe/η1-p-methylbenzyl/iPr2 (4iPr2Fe), Co/η1-p-methylbenzyl/Me3 (4Me3Co), Fe/η1-p-methylbenzyl/Me3 (4Me3Fe), Co/η1-α-naphthylmethyl/iPr2 (5iPr2Co),...
Fe(III)−catecholato complexes with the hydrotris(pyrazolyl)borate ligands (TpR; R denotes substituents of 3- and 5-positions pyrazolyl rings) are synthesized as structural functional models for catechol dioxygenase enzymes. Coordination geometry Fe centers depends on steric hindrance TpR ligands. O2 treatment TpPri2FeIII(DBC) (DBCH2 = 3,5-di-tert-butylcatechol) affords major products those derived from extradiol cleavage catechol, although a highly hindered ligand complex,...
By using a hindered tripodal ligand, hydrotris(3-tert-butyl-5-isopropylpyrazol-1-yl)borate HB(3-tBu-5-iPrpz)(3), series of monomeric ferrous complexes having acetate, hydroxide, and benzoylformate ligands were synthesized. Reaction KHB(3-tBu-5-iPrpz)(3) with anhydrous Fe(OAc)(2) yielded acetato Fe(OAc)[HB(3-tBu-5-iPrpz)(3)] (1) Fe(OAc)[HB(3-tBu-5-iPrpz)(3)](3-iPr-5-tBupzH) (2). A hydroxo complex Fe(OH)[HB(3-tBu-5-iPrpz)(3)] (3) was prepared by the treatment 1 or 2 aqueous NaOH. The geometry...
Substrate-dependent reactivity: The nickel(II) alkylperoxo complex 1 (see structure), obtained by the dehydrative condensation of hydroxo with tert-butylhydroperoxide has a unique structure; coordination mode OO moiety is an intermediate between η1 and η2. Compound exhibits substrate-dependent reactivity toward aliphatic CH, phosphines, carbon monoxide, aldehydes.
Abstract Our recent research on transition metal complexes containing hydrotris(pyrazolyl)borato ligands (TpR), which ranges from bioinorganic chemistry of dioxygen to organometallic systems, is reviewed. The TpR ligand turns out be versatile in a wide variety inorganic studies, because the coordination properties (both steric and electronic) can finely tuned systematic manner by choosing appropriate substituents pyrazolyl rings serve purpose study (e.g. stabilization, activation,...
Abstract A dinuclear peroxotungstate, K 2 [{W(O)(O ) (H O)} (μ‐O)]⋅2 H O, exhibits high catalytic performance for the epoxidation of various allylic alcohols with only one equivalent hydrogen peroxide at 305 in water solvent. The effectiveness this system is evidenced by chemo‐, regio‐, and diastereoselectivity, stereospecificity alcohols. Furthermore, products/catalyst separation can be easily carried out simple extraction catalyst recovered reused maintenance performance.
CO2 contamination in air is fixed by a binuclear di-µ-hydroxo copper(II) complex to give corresponding µ-carbonato of which the crystal structure established X-ray crystallography.
Dehydrative condensation of the hydroxopalladium complex (Tp(iPr2))(py)Pd-OH (1) with hydroperoxides (XOOH: X = H, t-Bu) produces corresponding (hydroperoxo)-, (Tp(iPr2))(py)Pd-OOH (2a), and (tert-butylperoxo)palladium complexes, (Tp(iPr2))(py)Pd-OOBu(t) (3). Treatment 2a PPh(3) results in concomitant ligand displacement giving (Tp(i)(Pr2))(Ph(3)P)Pd-OOH (2b) oxygenation O=PPh(3). Further between 1 gives mu-kappa(1):kappa(1)-peroxo (Tp(iPr2))(py)Pd-OO-Pd(Tp(iPr2))(py) (4), while...
S. Hikichi, M. Tanaka, Y. Moro-Oka and N. Kitajima, J. Chem. Soc., Commun., 1992, 814 DOI: 10.1039/C39920000814
The complexation of Dawson-type polyoxometalates [α-P2W18O62]6-, [α2-P2W17V1O62]7-, and [α-P2W15V3O62]9- with the macrocation ([Cr3O(OOCH)6(H2O)3]+) forms ionic crystals (NH4)4[Cr3O(OOCH)6(H2O)3]2[α-P2W18O62]·15H2O (1a), (NH4)5[Cr3O(OOCH)6(H2O)3]2[α2-P2W17V1O62]·15H2O (2a), (NH4)7[Cr3O(OOCH)6(H2O)3]2[α-P2W15V3O62]·15H2O (3a), respectively. compounds 1a−3a show honeycomb packing symmetry constituent ions reflect on crystal structures. lengths a axes are almost same, while those c decrease in...
Partial protonation of a divacant lacunary Keggin-type silicodecatungstate in an anhydrous organic solvent led to dehydrative condensation and formation novel S-shaped disilicoicosatungstate (see picture). The cluster efficiently promotes Baeyer–Villiger oxidation cycloalkanones with high turnover numbers (TONs, ≥1900) selectivities (≥90 %) for the corresponding lactones. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z502543_s.pdf...