NHC-Stabilized Au10 Nanoclusters and Their Conversion to Au25 Nanoclusters

Herein, we describe the synthesis of a toroidal Au10 cluster stabilized by N-heterocyclic carbene and halide ligands via reduction of the corresponding NHC−Au−X complexes (X = Cl, Br, I). The significant effect of the halide ligands on the formation, stability, and further conversions of these clusters is presented. While solutions of the chloride derivatives of Au10 show no change even upon heating, the bromide derivative readily undergoes conversion to form a biicosahedral Au25 cluster at room temperature. For the iodide derivative, the formation of a significant amount of Au25 was observed even upon the reduction of NHC−Au−I. The isolated bromide derivative of the Au25 cluster displays a…