Sc3+-triggered oxoiron(IV) formation from O2 and its non-heme iron(II) precursor via a Sc3+-peroxo-Fe3+ intermediate.

We report that redox-inactive Sc(3+) can trigger O2 activation by the Fe(II)(TMC) center (TMC = tetramethylcyclam) to generate the corresponding oxoiron(IV) complex in the presence of BPh4(-) as an electron donor. To model a possible intermediate in the above reaction, we generated an unprecedented Sc(3+) adduct of [Fe(III)(η(2)-O2)(TMC)](+) by an alternative route, which was found to have an Fe(3+)-(μ-η(2):η(2)-peroxo)-Sc(3+) core and to convert to the oxoiron(IV) complex. These results have important implications for the role a Lewis acid can play in facilitating O-O bond cleavage during the course of O2 activation at non-heme iron centers.