Density functional theory studies on the reduction of H₂O₂ on a nonheme iron center is shown to lead to dioxygen products efficiently through the formation of a μ-1,2-peroxo bridged diiron(III)dihydroxo complex from two iron(IV)-oxo(hydroxo) intermediates.

Abstract

Hydrogen peroxide is a versatile reductant that under the right conditions can react to form dioxygen in an electrochemical reaction. This reaction has a low carbon footprint and applications are being sought for batteries. In this work a computational study is presented on a recently reported nonheme iron(II) complex where we study mechanistic pathways leading to dioxygen formation from H₂O₂. The work shows that upon reduction of the iron(III)-hydroperoxo species it rapidly leads through heterolytic cleavage of the dioxygen bond to form iron(IV)-oxo(hydroxo). The dimerization reaction of two iron(IV)-oxo(hydroxo) complexes then leads to formation of the dioxygen bond rapidly with small barriers. Dissociation of the dimer expels dioxygen in an exothermic reaction. An alternative mechanism through the formation of a μ-1,2-peroxo-μ-1,1-hydroperoxodiiron(II) intermediate was also tested but found to be highly endergonic. These studies highlight the electrochemical feasibilities of nonheme iron(III)-hydroperoxo complexes.