On the Reactivity of NHCtBuAuCl towards Rb6Cs6Si17: The First Gold-Silicon Cluster [(NHCtBuAu)6(η2-Si4)]Cl2·7NH3 and an Imide Capped Gold Triangle (NHCtBuAu)3NHCl

Abstract

Crystals of the two new compounds (NHCtBuAu)3NHCl and [(NHCtBuAu)6(η2-Si4)]Cl2·7NH3 could be isolated from the reaction of Rb6Cs6Si17 with NHCtBuAuCl in the presence of [2.2.2]-cryptand in liquid ammonia. Both compounds were characterized by single-crystal X-ray diffraction and crystallize trigonally without any alkali metals or chelating ligands. Additionally, the crystal of [(NHCtBuAu)6(η2-Si4)]Cl2·7NH3 was further interpreted by means of ELF and NBO calculations. In the case of (NHCtBuAu)3NHCl, NMR experiments provided an exceptional insight into the reaction processes in solution and allowed for the detection of sequential precursors. In the class of capped gold triangles (NHCtBuAu)3NHCl impresses with its unique characteristics of being capped by an imide and bound to N-heterocyclic carbenes as ligands instead of the ubiquitously employed phosphines. The gold capped silicon tetrahedron [(NHCtBuAu)6(η2-Si4)]Cl2·7NH3 represents the first known silicide-gold compound, as well as the first known functionalized Zintl anion, crystallized with a cationic central moiety.