Ligand Protected Gold Alloy Clusters as Superatoms

Density functional study of the experimentally observed ligand-protected gold alloy clusters reveal the same stabilization mechanism as in ligand protected pure AuN: the delocalized s-electron subsystem of a high symmetry metal core exhibits a shell closing. On the basis of this observation it is predicted that the substitution of a single Au atom in the well-known Au25(SR)18 compound with Pd, Ag, and Cd will produce stable clusters resulting in a method to tune redox properties in such a nanoscale building block. Similar shell closings are shown to stabilize the cores of experimentally known carbonyl protected nickel-gold and nickel-silver clusters. These species can be understood as structurally as well as electronically separated, weakly interacting gold/silver and nickel-carbonyl subsystems.