Switchover of the Mechanism between Electron Transfer and Hydrogen-Atom Transfer for a Protonated Manganese(IV)–Oxo Complex by Changing Only the Reaction Temperature

Jieun Jung, Surin Kim, Yong Min Lee, Wonwoo Nam, Shunichi Fukuzumi

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Hydroxylation of mesitylene by a nonheme manganese(IV)–oxo complex, [(N4Py)MnIV(O)]2+(1), proceeds via one-step hydrogen-atom transfer (HAT) with a large deuterium kinetic isotope effect (KIE) of 3.2(3) at 293 K. In contrast, the same reaction with a triflic acid-bound manganese(IV)-oxo complex, [(N4Py)MnIV(O)]2+-(HOTf)2(2), proceeds via electron transfer (ET) with no KIE at 293 K. Interestingly, when the reaction temperature is lowered to less than 263 K in the reaction of 2, however, the mechanism changes again from ET to HAT with a large KIE of 2.9(3). Such a switchover of the reaction mechanism from ET to HAT is shown to occur by changing only temperature in the boundary region between ET and HAT pathways when the driving force of ET from toluene derivatives to 2 is around −0.5 eV. The present results provide a valuable and general guide to predict a switchover of the reaction mechanism from ET to the others, including HAT.

Original languageEnglish
Pages (from-to)7450-7454
Number of pages5
JournalAngewandte Chemie - International Edition
Volume55
Issue number26
DOIs
StatePublished - 20 Jun 2016

Keywords

  • bioinorganic chemistry
  • electron transfer
  • hydrogen atom transfer
  • manganese(IV)-oxo complex
  • mechanism switchover

Fingerprint

Dive into the research topics of 'Switchover of the Mechanism between Electron Transfer and Hydrogen-Atom Transfer for a Protonated Manganese(IV)–Oxo Complex by Changing Only the Reaction Temperature'. Together they form a unique fingerprint.

Cite this