Core Charge Density Dominated Size-Conversion from Au6 P8 to Au8 P8 Cl2.

The stimulus-response of metal nanoclusters is crucial to their applications in catalysis and bio-clinics, etc. However, its mechanistic origin has not been well studied. Herein, the mechanism of the AuI PPh3 Cl-induced size-conversion from [Au6 (DPPP)4 ]2+ to [Au8 (DPPP)4 Cl2 ]2+ (DPPP is short for 1,3-bis(diphenylphosphino)propane) is theoretically investigated with density functional theory (DFT) calculations. The optimal size-growth pathway, and the key structural parameters were elucidated. The Au-P bond dissociation steps are key to the size-growth, the easiness of which was determined by the charge density of the metallic core of the cluster precursors (i.e., "core charge density"). This study sheds light on the inherent structure-reactivity relationships during the size-conversion, and will benefit the deep understanding on the kinetics of more complex systems.