A Ruthenium(III)–Oxyl Complex Bearing Strong Radical Character |
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| Authors: | Yoshihiro Shimoyama Dr. Tomoya Ishizuka Dr. Hiroaki Kotani Prof. Dr. Yoshihito Shiota Prof. Dr. Kazunari Yoshizawa Dr. Kaoru Mieda Prof. Dr. Takashi Ogura Dr. Toshihiro Okajima Prof. Dr. Shunsuke Nozawa Prof. Dr. Takahiko Kojima |
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| Affiliation: | 1. Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki, Japan;2. Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka, Japan;3. Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center, Hyogo, Japan;4. Kyushu Synchrotron Light Research Center, Saga, Japan;5. Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Ibaraki, Japan |
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| Abstract: | Proton‐coupled electron‐transfer oxidation of a RuII?OH2 complex, having an N‐heterocyclic carbene ligand, gives a RuIII?O. species, which has an electronically equivalent structure of the RuIV=O species, in an acidic aqueous solution. The RuIII?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 RuIII?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 RuIII?O. complex bearing a strong radical character as the active species. |
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| Keywords: | catalysis N-heterocyclic carbenes oxyl radicals ruthenium substrate oxidation |
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