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 [Pt 2 Au 36 (SC 6 H 13 ) 24 ] 2– and [Pd 2 Au 36 (SC 6 H 13 ) 24 ] 0, respectively. Voltammetric investigations show that these clusters exhibit drastically different electronic structures; whereas the HOMO–LUMO gap of [Pt 2 Au 36 (SC 6 H 13 ) 24 ] 2– is found to be 0.95 V, that of [Pd 2 Au 36 (SC 6 H 13 ) 24 ] 0 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 [Pd 2 Au 36 (SC 6 H 13 ) 24 ] 0 reveals that the rod-like M 2 Au 21 core becomes more flattened upon Pd-doping. Reversible geometrical interconversion between [Pt 2 Au 36 (SC 6 H 13 ) 24 ] 0 and [Pt 2 Au 36 (SC 6 H 13 ) 24 ] 2– is clearly demonstrated by manipulating the oxidation state of the cluster.