Generation of an Isolable, Monomeric Manganese(V)–Oxo Complex from O2 and Visible Light

The direct conversion of a Mn(III) complex [(TBP(8)Cz)Mn(III) (1)] to a Mn(V)-oxo complex [(TBP(8)Cz)Mn(V)(O) (2)] with O(2) and visible light is reported. Complex 1 is also shown to function as an active photocatalyst for the oxidation of PPh(3) to OPPh(3). Mechanistic studies indicate that the photogeneration of 2 does not involve singlet oxygen but rather likely occurs via a free-radical mechanism upon photoactivation of 1.