Gold Nanoclusters Supported on MgO:  Synthesis, Characterization, and Evidence of Au₆

Abstract

Gold nanoclusters on MgO powder were prepared from adsorbed [Au(CH3)2(C5H7O2)] and characterized by infrared and X-ray absorption spectroscopies. Treatment of the samples in He or H2 at increasing temperatures removed CH3 and C5H7O2 ligands and caused the gold to aggregate into nanoclusters of increasing size, ultimately those with the properties of metallic gold. Treatment in He at 373 K gave clusters that are inferred to be nearly monodisperse Au6, with first- and second-shell Au−Au coordination numbers of 4.0 ± 0.4 and 1.0 ± 0.1, respectively, corresponding to Au6 octahedra.