Dopant-Dependent Electronic Structures Observed for MAu(SCH) Clusters (M = Pt, Pd).

Heteroatom doping is a powerful means to tune the optical and electronic properties of gold clusters at the atomic level. We herein report that doping a Au cluster with Pt and Pd atoms leads to core-doped [PtAu(SCH)] and [PdAu(SCH)], respectively. Voltammetric investigations show that these clusters exhibit drastically different electronic structures; whereas the HOMO-LUMO gap of [PtAu(SCH)] is found to be 0.95 V, that of [PdAu(SCH)] is drastically decreased to 0.26 V, suggesting Jahn-Teller distortion of the 12-electron cluster. Density functional investigations confirm that the HOMO-LUMO gap of the Pd-doped cluster is indeed reduced. Analysis of the optimized geometry for the 12-electron [PdAu(SCH)] reveals that the rod-like MAu core becomes more flattened upon Pd-doping. Reversible geometrical interconversion between [PtAu(SCH)] and [PtAu(SCH)] is clearly demonstrated by manipulating the oxidation state of the cluster.