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18 results on '"Mieda, Kaoru"'

6. A Ruthenium(III)-Oxyl Complex Bearing Strong Radical Character

Author

Shimoyama, Yoshihiro, primary, Ishizuka, Tomoya, additional, Kotani, Hiroaki, additional, Shiota, Yoshihito, additional, Yoshizawa, Kazunari, additional, Mieda, Kaoru, additional, Ogura, Takashi, additional, Okajima, Toshihiro, additional, Nozawa, Shunsuke, additional, and Kojima, Takahiko, additional

Published
2016
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7. Frontispiece: Formation and High Reactivity of the anti -Dioxo Form of High-Spin μ-Oxodioxodiiron(IV) as the Active Species That Cleaves Strong C−H Bonds

Author

Kodera, Masahito, primary, Ishiga, Shin, additional, Tsuji, Tomokazu, additional, Sakurai, Katsutoshi, additional, Hitomi, Yutaka, additional, Shiota, Yoshihito, additional, Sajith, P. K., additional, Yoshizawa, Kazunari, additional, Mieda, Kaoru, additional, and Ogura, Takashi, additional

Published
2016
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9. A Model for the Active-Site Formation Process in DMSO Reductase Family Molybdenum Enzymes Involving Oxido−Alcoholato and Oxido−Thiolato Molybdenum(VI) Core Structures

Author

Sugimoto, Hideki, primary, Sato, Masanori, additional, Asano, Kaori, additional, Suzuki, Takeyuki, additional, Mieda, Kaoru, additional, Ogura, Takashi, additional, Matsumoto, Takashi, additional, Giles, Logan J., additional, Pokhrel, Amrit, additional, Kirk, Martin L., additional, and Itoh, Shinobu, additional

Published
2016
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16. A Ruthenium(III)-Oxyl Complex Bearing Strong Radical Character.

Author

Shimoyama Y, Ishizuka T, Kotani H, Shiota Y, Yoshizawa K, Mieda K, Ogura T, Okajima T, Nozawa S, and Kojima T

Abstract

Proton-coupled electron-transfer oxidation of a Ru II -OH 2 complex, having an N-heterocyclic carbene ligand, gives a Ru III -O . species, which has an electronically equivalent structure of the Ru IV =O species, in an acidic aqueous solution. The Ru III -O . complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru-O bond showed a lower-energy Raman scattering at 732 cm -1 and the Ru-O bond length was estimated to be 1.77(1) Å. The Ru III -O . complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C-H abstraction from the formyl group by the Ru III -O . complex bearing a strong radical character as the active species., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2016
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17. Formation and High Reactivity of the anti-Dioxo Form of High-Spin μ-Oxodioxodiiron(IV) as the Active Species That Cleaves Strong C-H Bonds.

Author

Kodera M, Ishiga S, Tsuji T, Sakurai K, Hitomi Y, Shiota Y, Sajith PK, Yoshizawa K, Mieda K, and Ogura T

Abstract

Recently, it was shown that μ-oxo-μ-peroxodiiron(III) is converted to high-spin μ-oxodioxodiiron(IV) through O-O bond scission. Herein, the formation and high reactivity of the anti-dioxo form of high-spin μ-oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic-absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of μ-oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene

Published
2016
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18. A Model for the Active-Site Formation Process in DMSO Reductase Family Molybdenum Enzymes Involving Oxido-Alcoholato and Oxido-Thiolato Molybdenum(VI) Core Structures.

Author

Sugimoto H, Sato M, Asano K, Suzuki T, Mieda K, Ogura T, Matsumoto T, Giles LJ, Pokhrel A, Kirk ML, and Itoh S

Subjects
Catalytic Domain, Crystallography, X-Ray, Molecular Structure, Spectrophotometry, Ultraviolet, Iron-Sulfur Proteins chemistry, Molybdenum chemistry, Oxidoreductases chemistry
Abstract

New bis(ene-1,2-dithiolato)-oxido-alcoholato molybdenum(VI) and -oxido-thiolato molybdenum(VI) anionic complexes, denoted as [Mo(VI)O(ER)L2](-) (E = O, S; L = dimethoxycarboxylate-1,2-ethylenedithiolate), were obtained from the reaction of the corresponding dioxido-molybdenum(VI) precursor complex with either an alcohol or a thiol in the presence of an organic acid (e.g., 10-camphorsulfonic acid) at low temperature. The [Mo(VI)O(ER)L2](-) complexes were isolated and characterized, and the structure of [Mo(VI)O(OEt)L2](-) was determined by X-ray crystallography. The Mo(VI) center in [Mo(VI)O(OEt)L2](-) exhibits a distorted octahedral geometry with the two ene-1,2-dithiolate ligands being symmetry inequivalent. The computed structure of [Mo(VI)O(SR)L2](-) is essentially identical to that of [Mo(VI)O(OR)L2](-). The electronic structures of the resulting molybdenum(VI) complexes were evaluated using electronic absorption spectroscopy and bonding calculations. The nature of the distorted O(h) geometry in these [Mo(VI)O(EEt)L2](-) complexes results in a lowest unoccupied molecular orbital wave function that possesses strong π* interactions between the Mo(d(xy)) orbital and the cis S(p(z)) orbital localized on one sulfur donor from a single ene-1,2-dithiolate ligand. The presence of a covalent Mo-S(dithiolene) bonding interaction in these monooxido Mo(VI) compounds contributes to their low-energy ligand-to-metal charge transfer transitions. A second important d-p π bonding interaction derives from the ∼180° O(oxo)-Mo-E-C dihedral angle involving the alcoholate and thiolate donors, and this contributes to ancillary ligand contributions to the electronic structure of these species. The formation of [Mo(VI)O(OEt)L2](-) and [Mo(VI)O(SEt)L2](-) from the dioxidomolybdenum(VI) precursor may be regarded as a model for the active-site formation process that occurs in the dimethyl sulfoxide reductase family of pyranopterin molybdenum enzymes.

Published
2016
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