A Homoleptic Alkynyl‐Ligated [Au₁₃Ag₁₆L₂₄]³⁻ Cluster as a Catalytically Active Eight‐Electron Superatom

Abstract

A new alkynylated cluster [Au₁₃ Ag₁₆ (C₁₀ H₆ NO)₂₄ ]^3- is prepared by a NaBH₄ mediated reduction method. The AuAg clusters are confirmed by sophisticated characterization techniques. It has a unique "Au_center @Ag₁₂ @Au₁₂ Ag₄ " metal framework which is protected by 24 atypical alkyne ligands L (L=C₁₀ H₆ NO). The ligands construct a unique type of motif L-(Ag)-Au-(Ag)-L at the cluster interface, where the alkyne (C≡C) group of each L was linked by sharing an Au atom through the σ bonds and each C≡C group was discretely connected to a chemically different Ag atom (Ag_icosahedral /Ag_cap ) through π bonds. The electronic and optical properties of [Au₁₃ Ag₁₆ L₂₄ ]^3- were studied. DFT characterized the cluster as a clear 8-electron superatom, and peaks in the optical absorption spectrum were interpreted in terms of the P and D superatom states. The supported Au₁₃ Ag₁₆ L₂₄ /CeO₂ catalyst exhibited high catalytic activity and selectivity towards the A³ -coupling reaction involving benzaldehyde, diethylamine, and phenylacetylene.