Issue 4, 2012

Quantum chemical characterization of the mechanism of an iron-based water oxidation catalyst

Abstract

Theoretical models are used to demonstrate a catalytic cycle for the generation of O2 from an iron(III)-centered tetraamido macrocycle in water that is consistent with experimentally observed energetics in the presence of a sacrificial oxidant. Application of density functional theory and multireference second-order perturbation theory indicates that two proton-coupled electron transfer steps followed by an electron-transfer step first generate a reactive species that is well described as an iron(V)-oxo supported by a macrocycle that has also suffered a one-electron oxidation. Subsequent O–O bond formation occurs through water nucleophilic attack on the iron-oxo with the local solvent shell serving to relay a proton away from the reacting partners. Subsequent steps of proton-coupled electron transfer and low-energy water displacement of O2 complete the catalytic cycle. Modification of the TAML ligand to reduce the likely instability of the non-innocent aromatic radical may prove useful in future catalyst design.

Graphical abstract: Quantum chemical characterization of the mechanism of an iron-based water oxidation catalyst

Supplementary files

Article information

Article type
Edge Article
Submitted
08 Dec 2011
Accepted
05 Jan 2012
First published
12 Jan 2012

Chem. Sci., 2012,3, 1293-1299

Quantum chemical characterization of the mechanism of an iron-based water oxidation catalyst

M. Z. Ertem, L. Gagliardi and C. J. Cramer, Chem. Sci., 2012, 3, 1293 DOI: 10.1039/C2SC01030E

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