Computational Study on O–O Bond Formation on a Mononuclear Non-Heme Iron Center

Abstract

Cleavage and formation of the O–O bond in dioxygen is among the most important metal-dependent processes in Nature. The former process has been mimicked structurally and functionaly with a number of biomimetic iron complexes. The reverse process, namely the dioxygen bond formation, however, appears unfavorable with iron. Over the years many attempts have been made to oxidize water on a mononuclear iron center through reactions with peroxide. In this work we present a computational study focused on the mechanism of dioxygen formation on two mononuclear non-heme iron(IV)-oxo species upon addition of peracid (m-chloroperbenzoic acid, mCPBA). A range of test reactions and sequences are analyzed with thermochemical cycles with respect to the thermodynamic and kinetic feasibility of product formation. The work shows that iron-borne O–O bond formation through peracid attack at FeIVO indeed is feasible through two competing pathways. These are initiated by homolytic inner-sphere splitting of the RC(O)OO-H and the RC(O)O-OH bond in the peracid, respectively.