The “innocent” role of Sc3+ on a non-heme Fe catalyst in an O2 environment

Abstract

Density functional theory calculations have been used to investigate the reaction mechanism proposed for the formation of an oxoiron(IV) complex [Fe^IV(TMC)O]²⁺ (P) (TMC = 1,4,8,11-tetramethylcyclam) starting from a non-heme reactant complex [Fe^II(TMC)]²⁺ (R) and O₂ in the presence of acid H⁺ and reductant BPh₄⁻. We also addressed the possible role of redox-inactive Sc³⁺ as a replacement for H⁺ acid in this reaction to trigger the formation of P. Our computational results substantially confirm the proposed mechanism and, more importantly, support that Sc³⁺ could trigger the O₂ activation, mainly dictated by the availability of two electrons from BPh₄⁻, by forming a thermodynamically stable Sc³⁺–peroxo–Fe³⁺ core that facilitates O–O bond cleavage to generate P by reducing the energy barrier. These insights may pave the way to improve the catalytic reactivity of metal–oxo complexes in O₂ activation at non-heme centers.