[AuAgH(SPhCl)]: An Au-Ag Alloy Nanocluster with 12 Hydrides and Its Enlightenment on Nanocluster Structural Evolution.

The structural determination of alloy hydride nanoclusters with high nuclearity remains challenging. We herein report the synthetic procedure and the structural elucidation of an Au-Ag alloy nanocluster with 12 hydride ligands-[AuAgH(SPhCl)]. The structure of [AuAgH(SPhCl)] comprises an AuAg kernel that is stabilized by 12 hydride ligands, 8 thiol bridges, and 6 Ag(SR) motif units. The 12 hydride ligands in AuAg have been confirmed by both H NMR and ESI-MS measurements, and their positions have been theoretically evaluated, located at the interlayer between the AuAg kernel and the Ag-SR shell. The metastable [AuAgH(SPhCl)] can convert to [AuAg(SPhCl)] spontaneously. Structurally, the AuAg kernel of [AuAgH(SPhCl)] could be regarded as the overlapping of two hollow AuAg cages via sharing an Ag line, which is in contrast to the solely icosahedral Au kernel of [AuAg(SPhCl)]. Besides, the overall construction of AuAg or AuAg follows a complementing or overlapping assembly mode, respectively. Overall, the structural anatomy of AuAgH(SPhCl) sheds some new insight into the structural evolution of metal nanoclusters.