Stable N-heterocyclic carbenes (2) represent an important new class of organometallic ligands, and have been employed in place of phosphines in transition metal catalysts for a number of important reactions (olefin methathesis, e.g.), in some cases providing superior catalysis.  The success of N-heterocyclic carbenes as ligands in metal catalysts invites the study of catalytic properties of analogous silylene-metal complexes.  Thus, the incorporation of a stable silylene (1) into metal complexes, and their subsequent application as catalysts in organometallic reactions has been a primary focus of our research. 

The catalytic activity of a silylene-palladium complex (3) has been demonstrated by means of the Stille reaction (see reaction scheme below), a palladium-catalyzed reaction that affords new carbon-carbon bonds under remarkably mild reaction conditions.  Model Stille reactions, employing traditional catalysts such as Pd(PPh₃)₄ have been performed and the yields and reaction rates have been  compared to those obtained using compound 3 as the catalyst.  In some cases, the latter catalyst affords higher yields of coupled product, with lower percentages of undesirable homocoupled products.  Preliminary results will be summarized.