Same Magic Number but Different Arrangement: Alkynyl‐Protected Au₂₅ with <i>D</i>₃ Symmetry

Abstract

Two homoleptic alkynyl-protected gold clusters with compositions of Na[Au₂₅ (C≡CAr)₁₈ ] and (Ph₄ P)[Au₂₅ (C≡CAr)₁₈ ] (Na⋅1 and Ph₄ P⋅1, Ar=3,5-bis(trifluoromethyl)phenyl) were synthesized via a direct reduction method. 1 is a magic cluster analogous to [Au₂₅ (SR)₁₈ ]^- in terms of electron counts and metal-to-ligand ratio. Single-crystal structure analysis reveals that 1 has an identical Au₁₃ kernel to [Au₂₅ (SR)₁₈ ]^- , but adopts a distinctly different arrangement of the six peripheral dimer staple motifs. The steric hindrance of alkynyl ligands is responsible for the D₃ arrangement of Au₂₅ . The introduction of alkynyl also significantly changes the optical absorption features of the nanocluster as supported by DFT calculations. This magic cluster confirms that there is a similar but quite different parallel alkynyl-protected metal cluster universe in comparison to the thiolated one.