Synthesis of RhH-doped Au–Ag alloy nanoclusters and dopant evolution

Abstract

Doping atomically precise metal nanoclusters (NCs) with heterometals is a powerful method for tuning the physicochemical properties of the original NCs at the atomic level. While the heterometals incorporated into metal NCs are limited to group 10–12 metals with closed d-shells, the doping of open d-shell metals remains largely unexplored. Herein, we report the synthesis of Rh-doped Au–Ag alloy NCs by a metal-exchange reaction of [RhHAg₂₄(SPhMe₂)₁₈]²⁻ NCs with an Au–thiolate complex. Combined experimental and theoretical structural studies revealed that the synthesized product is a dianionic [RhHAu_xAg_24−x(SPhMe₂)₁₈]²⁻ NC (x = 8–12), consisting of RhH dopant, Au-rich kernel, and Ag-thiolate staple motifs, with the superatomic 8-electron configuration (1S²1P⁶). Under aerobic conditions, the synthesized NCs underwent kernel evolution to generate a 6-electron [RhAu_xAg_24−x(SPhMe₂)₁₈]¹⁻ NC (1S²1P⁴), which was initiated by the desorption of hydride from the kernel. Structural analysis of the [RhHAu_xAg_24−x(SPhMe₂)₁₈]²⁻ NC suggests that the kernel evolution is induced by the change in chemical bonds surrounding the hydride in the Au-rich kernel.