Gold nanoclusters supported on MgO:: Synthesis, characterization, and evidence of Au6

Gold nanoclusters on MgO powder were prepared from adsorbed [Au(CH(3))(2)(C(5)H(7)O(2))] and characterized by infrared and X-ray absorption spectroscopies. Treatment of the samples in He or H(2) at increasing temperatures removed CH(3) and C(5)H(7)O(2) 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 Au(6), with first- and second-shell Au-Au coordination numbers of 4.0 +/- 0.4 and 1.0 +/- 0.1, respectively, corresponding to Au(6) octahedra.