Computational Approaches for Redox Potentials of Iron(IV)‐oxido Complexes. Issue 22 (13th November 2020)

• Record Type: Journal Article
• Authors: Comba, Peter; Faltermeier, Dieter; Martin, Bodo
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 646:Issue 22(2020)
• Page Start: 1839
• Page End: 1845
• Publication Date: 2020-11-13
• Subjects: Redox chemistry -- Quantum chemistry -- Non‐heme iron -- Redox potential -- Proton‐coupled electron transfer; Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.202000355
• Languages: English
• ISSNs: 0044-2313

Abstract

Abstract : The potential of the redox couple Fe IV =O / Fe III –O is of interest for the reactivity of the high‐valent nonheme iron oxidants in enzymes and bioinspired small molecule systems but, unfortunately, experimentally it so far is very poorly described. Discussed are three computational methods that are used in combination with available experimental data derived from titrations of Fe IV =O species with ferrocene derivatives in dry acetonitrile, and from spectroelectrochemical titrations of Fe III –OH complexes in wet acetonitrile, i.e. describing the Fe IV =O / Fe III –OH couple – both data sets are known to have some ambiguities. First, a DFT‐based method is used to compute the E° values of 14 Fe IV =O / Fe III –O couples with an error margin of around 110 mV. A subset of four species of the original data set is used to evaluate a DLPNO‐CCSD(T) based approach, and another subset of complexes, where the spectroelectrochemically determined Fe IV =O / Fe III –OH potentials are also known, are used for a Bordwell‐Polanyi analysis, which also yield p K a values. It is shown that the three approaches lead to a consistent picture but due to possible ambiguities with the experimental data, it currently is not possible to fully evaluate the accuracy of the used approaches. Abstract :