Phosphine-Scavenging Role of Gold(I) Complexes from Pd(PtBu3)2 in the Bimetallic Catalysis of Carbostannylation of Alkynes

Density functional theory (DFT) at the M06 level was utilized to compare the reactivity of Pd­(PtBu3)2 with that of Pd2(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(PtBu3)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 ZnCl2 might have potential for use as phosphine scavengers from palladium(0) bis­(phosphine) complexes.