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 = N,N-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.