Direct oxygen atom transfer versus electron transfer mechanisms in the phosphine oxidation by nonheme Mn(IV)-oxo complexes

Direct oxygen atom transfer from a nonheme Mn(IV)-oxo complex, [(Bn-TPEN)Mn-IV(O)](2+), to triphenylphosphine (Ph3P) derivatives occurs with a significant steric effect resulting from the ortho-substituents on the phenyl group of the Ph3P derivatives, whereas the phosphine oxygenation by a Mn(IV)-oxo complex in the presence of HOTf occurs via an electron transfer mechanism without the substrate-steric effect.