Metal Exchange Method Using Au25 Nanoclusters as Templates for Alloy Nanoclusters with Atomic Precision

A metal exchange method based upon atomically precise gold nanoclusters (NCs) as templates is devised to obtain alloy NCs including CuxAu25-x(SR)(18), AgxAu25-x(SR)(18), Cd1Au24(SR)(18), and Hg1Au24(SR)(18) via reaction of the template with metal thiolate complexes of Cu-II, Ag-I, Cd-II, and Hg-II (as opposed to common salt precursors such as CuCl2, AgNO3, etc.). Experimental results imply that the exchange between gold atoms in NCs and those of the second metal in the thiolated complex does not necessarily follow the order of metal activity (i.e., galvanic sequence). In addition, the crystal structure of the exchange product (Cd1Au24(SR)(18)) is successfully determined, indicating that the Cd is in the center of the 13-atom icosahedral core. This metal exchange method is expected to become a versatile new approach for synthesizing alloy NCs that contain both high- and low-activity metal atoms.