Issue 40, 2023

Reaction landscape of a mononuclear MnIII–hydroxo complex with hydrogen peroxide

Abstract

Peroxomanganese species have been proposed as key intermediates in the catalytic cycles of both manganese enzymes and synthetic catalysts. However, many of these intermediates have yet to be observed. Here, we report the formation of a series of intermediates, each generated from the reaction of the mononuclear MnIII–hydroxo complex [MnIII(OH)(dpaq2Me)]+ with hydrogen peroxide under slightly different conditions. By changing the acidity of the reaction mixture and/or the quantity of hydrogen peroxide added, we are able to control which intermediate forms. Using a combination of electronic absorption, 1H NMR, EPR, and X-ray absorption spectroscopies, as well as density functional theory (DFT) and complete active space self-consistent field (CASSCF) calculations, we formulate these intermediates as the bis(μ-oxo)dimanganese(III,IV) complex [MnIIIMnIV(μ-O)2(dpaq2Me)2]+, the MnIII–hydroperoxo complex [MnIII(OOH)(dpaq2Me)]+, and the MnIII–peroxo complex [MnIII(O2)(dpaq2Me)]. The formation of the MnIII–hydroperoxo species from the reaction of a MnIII–hydroxo complex with hydrogen peroxide mimics an elementary reaction proposed for many synthetic manganese catalysts that activate hydrogen peroxide.

Graphical abstract: Reaction landscape of a mononuclear MnIII–hydroxo complex with hydrogen peroxide

Supplementary files

Article information

Article type
Paper
Submitted
16 Aug 2023
Accepted
22 Sep 2023
First published
22 Sep 2023

Dalton Trans., 2023,52, 14350-14370

Author version available

Reaction landscape of a mononuclear MnIII–hydroxo complex with hydrogen peroxide

E. N. Grotemeyer, J. D. Parham and T. A. Jackson, Dalton Trans., 2023, 52, 14350 DOI: 10.1039/D3DT02672H

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