Au₁₉ Nanocluster Featuring a V‑Shaped Alkynyl–Gold Motif

A novel Au₁₉ nanocluster with a composition of [Au₁₉(PhCC)₉(Hdppa)₃]­(SbF₆)₂ was synthesized (Hdppa = <i>N</i>,<i>N</i>-bis­(diphenylphosphino)­amine). Single crystal X-ray structural analysis reveals that the cluster comprises a centered icosahedral Au₁₃ core hugged by three V-shaped PhCC–Au–CC­(Ph)–Au–CCPh motifs. Such motif is observed for the first time in an alkynyl-protected gold nanocluster. The Au₁₉ cluster shows two main optical-absorption bands at 1.25 and 2.25 eV, confirmed by time-dependent density functional theory. Orbital analysis indicates that PhCC– groups can actively participate in the frontier orbitals of the whole cluster. The new Au₁₉ cluster and the novel alkynyl–gold motif open the door to understanding the alkynyl–gold interface and discovering many potential members of this new class of gold clusters