A Chromium(III)-Superoxo Complex as a Three-Electron Oxidant with a Large Tunneling Effect in Multi-Electron Oxidation of NADH Analogues
- 주제(키워드) chromium(III)-superoxo complexes , hydride transfer , hydrogen atom transfer , NADH analogues , three-electron oxidant
- 등재 SCIE, SCOPUS
- 발행기관 WILEY-V C H VERLAG GMBH
- 발행년도 2017
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000144565
- 본문언어 영어
- Published As http://dx.doi.org/10.1002/ange.201611709
초록/요약
Metal-superoxo species are involved in a variety of enzymatic oxidation reactions, and multi-electron oxidation of substrates is frequently observed in those enzymatic reactions. ACr(III)-superoxo complex, [Cr-III(O-2)(TMC)(Cl)](+) (1; TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), is described that acts as a novel three-electron oxidant in the oxidation of dihydronicotinamide adenine dinucleotide (NADH) analogues. In the reactions of 1 with NADH analogues, a Cr-IV-oxo complex, [Cr-IV(O)(TMC)(Cl)](+) (2), is formed by a heterolytic O-O bond cleavage of a putative Cr-II-hydroperoxo complex, [Cr-II(OOH)(TMC)(Cl)], which is generated by hydride transfer from NADH analogues to 1. The comparison of the reactivity of NADH analogues with 1 and p-chloranil (Cl(4)Q) indicates that oxidation of NADH analogues by 1 proceeds by proton-coupled electron transfer with a very large tunneling effect (for example, with a kinetic isotope effect of 470 at 233 K), followed by rapid electron transfer.
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