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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| Institution: | 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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