A New Mechanism for Metal-Catalyzed Stannane Dehydrocoupling Based on α-H-Elimination in a Hafnium Hydrostannyl Complex

The hafnium hydrostannyl complex CpCp*Hf(SnHMes2)Cl (Cp* = η5-C5Me5) has been synthesized from the reaction of CpCp*Hf(H)Cl with Mes2SnH2. This compound has been identified as an intermediate in the metal-catalyzed dehydrocoupling of Mes2SnH2 to the distannane Mes2HSnSnHMes2 (Mes = 2,4,6-trimethylphenyl). The dehydrocoupling in this system appears to occur by elimination of :SnMes2 from CpCp*Hf(SnHMes2)Cl, with Sn−Sn bond formation proceeding via insertion of the stannylene into a Sn−H bond.