Dopant-Dependent Electronic Structures Observed for M2Au36(SC6H13)(24) 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-38 cluster with Pt and Pd atoms leads to core-doped [Pt2Au36(SC6H13)(24)](2-) and [Pd2Au36(SC6H13)(24)], respectively. Voltammetric investigations show that these clusters exhibit drastically different electronic structures; whereas the HOMO-LUMO gap of [Pt2Au36(SC6H13)(24)](2-) is found to be 0.95 V, that of [Pd2Au36(SC6H13)(24)] 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 [Pd2Au36(SC6H13)(24)] reveals that the rod-like M2Au21 core becomes more flattened upon Pd-doping. Reversible geometrical interconversion between [Pt2Au36(SC6H13)(24)] and [Pt2Au36(SC6H13)(24)](2-) is clearly demonstrated by manipulating the oxidation state of the cluster.