Complexes with Atomic Gold Ions: Efficient Bis-Ligand Formation.

Complexes of atomic gold with a variety of ligands have been formed by passing helium nanodroplets (HNDs) through two pickup cells containing gold vapor and the vapor of another dopant, namely a rare gas, a diatomic molecule (H, N, O, I, P), or various polyatomic molecules (HO, CO, SF, CH, adamantane, imidazole, dicyclopentadiene, and fullerene). The doped HNDs were irradiated by electrons; ensuing cations were identified in a high-resolution mass spectrometer. Anions were detected for benzene, dicyclopentadiene, and fullerene. For most ligands L, the abundance distribution of AuL versus size displays a remarkable enhancement at = 2. The propensity towards bis-ligand formation is attributed to the formation of covalent bonds in AuL which adopt a dumbbell structure, L-Au-L, as previously found for L = Xe and C. Another interesting observation is the effect of gold on the degree of ionization-induced intramolecular fragmentation. For most systems gold enhances the fragmentation, i.e., intramolecular fragmentation in AuL is larger than in pure L. Hydrogen, on the other hand, behaves differently, as intramolecular fragmentation in Au(H) is weaker than in pure (H) by an order of magnitude.