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 PPh3 to OPPh3. 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.