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(O)], to triphenylphosphine (PhP) derivatives occurs with a significant steric effect resulting from the ortho-substituents on the phenyl group of the PhP 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.