The "innocent" role of Sc3+ on a non-heme Fe catalyst in an O-2 environment

Density functional theory calculations have been used to investigate the reaction mechanism proposed for the formation of an oxoiron(iv) complex [Fe-IV(TMC)0](2+) (P) (TIvIC = 1,4,8,11-tetramethylcyclam) starting from a non-heme reactant complex-EFell(TMC)1(2+) (R) and 02 in the presence of acid H+ and reductant BPV. 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 02 activation, mainly dictated by the availability of two electrons from BPV, by forming a thermodynamically stable Sc3+-peroxo-Fe3+ core that facilitates 0-0 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 02 activation at non-heme centers.