Disproportionation of H2O2 to Dioxygen on a Nonheme Iron Center. A Computational Study

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 and 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. We also tested an alternative mechanism through the formation of a μ-1,2-peroxo-μ-1,1-hydroperoxodiiron(II) intermediate but find the mechanism to be highly endergonic. These studies highlight the electrochemical feasibilities of nonheme iron(III)- hydroperoxo complexes.