Arylation of gold nanoclusters and insights into structure-related CO₂ reduction reaction performances

Research on arylgold complexes and ligand-protected gold nanoclusters has proceeded independently thus far due to the difficulty in controllably introducing aryl groups to synthesize arylgold nanoclusters. Herein we synthesized an arylgold Au₁₅ nanocluster, Au₁₅(DPPOE)₃(S-Ph ^<i>p</i> Me)₄(Ph)₂, thereby bridging the two independent research fields. Tetraarylborates were exploited as arylating agents to transfer aryl groups onto the nanocluster kernel, triggering the arylation of the Au₁₅ cluster while maintaining the molecular framework. Furthermore, two other arylgold Au₁₅ nanoclusters with halogenated surfaces were controllably synthesized by substituting the arylating agent NaBPh₄ with its benzene ring-halide derivatives. In addition, the change in the electronic structure from Au-SR to Au-aryl and the energetics of the arylation process from Au₁₅-SR to Au₁₅-Ph were elucidated computationally. Furthermore, the catalytic capability of the two Au₁₅ nanoclusters with nuanced ligand differences was investigated in the electrochemical reduction of CO₂, and the comparable reactivity of the two cluster-based nanocatalysts was theoretically rationalized. Our findings have cross-fertilized the fields of arylgold complexes and gold nanoclusters, pointing toward a new avenue of exploration for novel arylgold nanoclusters.