Heterodinuclear AuNi(CO)_<i>n</i>^– (<i>n</i> = 2–3) Complexes Featuring an Anionic Au^– as a Donor Ligand for Ni(CO)_<i>n</i>

The gas-phase heterodinuclear gold-nickel carbonyl AuNi(CO)_<i>n</i>^- (<i>n</i> = 2-3) anion complexes were mass-selected and studied by using photoelectron velocity-map imaging spectroscopy in combination with quantum-chemical calculations, which can establish both the geometries and electronic structures of these anions. These complexes are all confirmed to be singlet ground states with one gold atom bonded at the central nickel atom of the Ni(CO)_<i>n</i> moieties. Further bonding analyses indicate that unlike the alkali-metals as covalently bonded ligands to form the electron-sharing alkali-metal-nickel bonding in the alkali-metal-nickel carbonyl anionic complexes, the Au atom in the AuNi(CO)_<i>n</i>^- complexes serves as a datively bound ligand for Ni(CO)_<i>n</i> to form gold-to-nickel dative bonding.