Icosahedral gold cage clusters: M@Au12− (M=V, Nb, and Ta)

Abstract

We report the observation and characterization of a series of stable bimetallic 18-valence-electron clusters containing a highly symmetric 12-atom icosahedral Au cage with an encapsulated central heteroatom of Group VB transition metals, M@Au12− (M=V,Nb,Ta). Electronic and structural properties of these clusters were probed by anion photoelectron spectroscopy and theoretical calculations. Characteristics of the M@Au12− species include their remarkably high binding energies and relatively simple spectral features, which reflect their high symmetry and stability. The adiabatic electronic binding energies of M@Au12− were measured to be 3.70±0.03, 3.77±0.03, and 3.76±0.03 eV for M=V, Nb, and Ta, respectively. Comparison of density-functional calculations with experimental data established the highly symmetric icosahedral structures for the 18-electron cluster anions, which may be promising building blocks for cluster-assembled nanomaterials in the form of stoichiometric [M@Au12−]X+ salts.