Hydrosilylation of Aldehydes and Ketones Catalyzed by HalfSandwich Manganese( I) N-Heterocyclic Carbene Complexes

Easily available manganese(I) N-heterocyclic carbene (NHC) complexes, Cp(CO)(2)Mn(NHC), obtained in one step from industrially produced cymantrene, were evaluated as pre-catalysts in the hydrosilylation of carbonyl compounds under UV irradiation. Complexes with NHC ligands incorporating at least one mesityl group led to the most active and selective catalytic systems. A variety of aldehydes (13 examples) and ketones (11 examples) were efficiently reduced under mild conditions [Cp(CO)(2)Mn(IMes) (1mol%), Ph2SiH2 (1.5equiv.), h (350nm), toluene, 25 degrees C, 1-24h] with good functional group tolerance.