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- Title
A Chromium(III)-Superoxo Complex as a Three-Electron Oxidant with a Large Tunneling Effect in Multi-Electron Oxidation of NADH Analogues.
- Authors
Devi, Tarali; Lee, Yong-Min; Jung, Jieun; Sankaralingam, Muniyandi; Nam, Wonwoo; Fukuzumi, Shunichi
- Abstract
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. A CrIII-superoxo complex, [CrIII(O2)(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 CrIV-oxo complex, [CrIV(O)(TMC)(Cl)]+ ( 2), is formed by a heterolytic O−O bond cleavage of a putative CrII-hydroperoxo complex, [CrII(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 (Cl4Q) 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.
- Subjects
OXIDATION states; TETRAMETHYL compounds; NAD+ synthase; CHARGE exchange; PROTONS
- Publication
Angewandte Chemie International Edition, 2017, Vol 56, Issue 13, p3510
- ISSN
1433-7851
- Publication type
Article
- DOI
10.1002/anie.201611709