Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)-superoxo complex via a proton-coupled hydrogen atom transfer

Tarali Devi, Yong Min Lee, Shunichi Fukuzumi, Wonwoo Nam

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The sequential transfer of an electron, a proton and an electron in a hydride transfer from dihydronicotinamide adenine dinucleotide (NADH) and its analogues has never been separated well. In addition, the effect of acids on hydride transfer from an NADH analogue to a metal-superoxo species has yet to be reported. We report herein the first example of an acid-promoted hydride transfer from an NADH analogue, 10-methyl-9,10-dihydroacridine (AcrH2), to a Cr(iii)-superoxo complex, [(TMC)CrIII(O2)]2+, in the presence of HOTf in MeCN at 233 K. The acid-promoted hydride transfer from AcrH2 to [(TMC)CrIII(O2)]2+ occurs via a proton-coupled hydrogen atom transfer from AcrH2 to [(TMC)CrIII(O2)]2+ to produce a radical cation (AcrH2+) with an inverse deuterium isotope effect (KIE) of 0.93(5). AcrH2+ decayed via a proton transfer from AcrH2+ to AcrH2 with a KIE of 2.0(1), followed by the reaction of 10-methylacridinyl radical (AcrH) with [(TMC)CrIII(H2O2)]3+ to produce a 10-methylacridinium ion (AcrH+) and [(TMC)CrIII]3+. This work provides valuable insights into the mechanism of hydride transfer of NADH analogues by metal-superoxo intermediates, such as the switchover of the reaction mechanism from a one-step to a separated multi-step pathway in the presence of an acid.

Original languageEnglish
Pages (from-to)675-680
Number of pages6
JournalDalton Transactions
Volume50
Issue number2
DOIs
StatePublished - 14 Jan 2021

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