Density functional theory (DFT) at the M06 level was utilized to compare the reactivity of Pd(P t Bu 3 ) 2 with that of Pd 2 (dba) 3 in catalyzing carbostannylation of alkynes in the presence of [AuL] + , where L is a phosphine ligand. In both cases, a common active catalyst is found to be responsible for conducting the reaction. The underlying reason for this is that [AuL] + is capable of acting as a phosphine scavenger and removing both phosphines from Pd(P t Bu 3 ) 2 . The phosphine scavenger property of the cationic gold complexes may find applications in other catalytic coupling reactions. We also found that other Lewis acids such as AuCl, CuCl, and ZnCl 2 might have potential for use as phosphine scavengers from palladium(0) bis(phosphine) complexes.