On the Differences in the Mechanisms of Reduction of AuCl2- and Ag(H2O)2+ with BH4.

The mechanism of reduction of AuCl4-/AuCl3OH- by BH4- was analyzed by density functional theory (DFT). The results point out that Auatoms0 are not intermediates in the process. The derived mechanism differs considerably from that reported for the analogous process involving the reduction of Ag(H2O)2+ by BH4-. Thus, though both processes follow the Creighton procedure, the detailed mechanism differs significantly. For Au, the agglomeration starts with AuH2-, whereas for Ag, it starts with (H2O)AgH. Stopped-flow measurements support the complicated mechanism.