A first glance into mixed phosphine-stibine moieties as protecting ligands for gold clusters

Atomically precise gold clusters have attracted considerable research interest as their tunable structure-property relationships have resulted in widespread applications, from sensing and biomedicine to energetic materials and catalysis. In this article, the synthesis and optical properties of a novel [Au₆(SbP₃)₂][PF₆]₂ cluster are reported. Despite the lack of spherical symmetry in the core, the cluster shows exceptional thermal and chemical stability. Detailed structural attributes and optical properties are evaluated experimentally and theoretically. This, to the best of our knowledge, is the first report of a gold cluster protected via synergistic multidentate coordination of stibine (Sb) and phosphine moieties (P). To further show that the latter moieties give a set of unique properties that differs from monodentate phosphine-protected [Au₆(PPh₃)₆]²⁺, geometric structure, electronic structure, and optical properties are analyzed theoretically. In addition, this report also demonstrates the critical role of overall-ligand architecture in stabilizing mixed ligand-protected gold clusters.