Theory Revealing Unusual Non-Rebound Mechanisms Responsible for the Distinct Reactivities of O=MnIV=O and [HO-MnIV-OH]2+ in C-H Bond Activation

Dibyendu Mallick, Sason Shaik*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

This article uses theory to address the origins of the reactivity differences between MnIV=O and MnIV-OH complexes, having identical ligand spheres and metal oxidation states, toward 9,10-dihydroanthracene (DHA) under different pH conditions. Theory discovers different non-rebound mechanisms leading to unique products for the two complexes. One of these is a novel mechanism that operates under basic conditions and that rationalizes the formation of anthraquinone through an anthracene radical anion intermediate. In addition, the calculations reveal a rich mechanistic scheme having blended hydrogen atom transfer and proton-coupled electron transfer (HAT/PCET) with both proton transfer/electron transfer (PT/ET) and electron transfer/proton transfer (ET/PT) characters. The distinct nature of the transition states, such as PT/ET and ET/PT, for the second H-abstraction reactions from the substrate radical by the MnIV=O and MnIV-OH complexes accounts for the observed product distributions for these two species. The formation of an anthracene radical anion, and its participation in a unique non-rebound mechanism, is a testable prediction.

Original languageEnglish
Pages (from-to)2877-2888
Number of pages12
JournalACS Catalysis
Volume6
Issue number5
DOIs
StatePublished - 6 May 2016

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

Keywords

  • anthracene radical anion
  • ET/PT
  • Mn-hydroxo
  • Mn-oxo
  • non-rebound
  • PT/ET

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