Mechanistic Aspects of Transition-Metal Catalyzed Dehydrogenative Silane Coupling Reactions

Abstract Dehydrogenative silane couplings to give Si-Si bonded compounds are catalyzed by a number of transition-metal complexes. A mechanism based on transition-metal silylene complexes, LnM = SiR2, seems possible for some of these reactions; however, little evidence exists to support their involvement in known systems. Based on precedents that exist in stoichiometric reactions, a more likely mechanism for late transition-metal catalysts consists of oxidative addition/reductive elimination cycles. For early transition metal (d°) catalysts, evidence accumulated to date points toward a "σ-bond metathesis" mechanism based on concerted, 4-center transition states.