Probing the gold-hydrogen analogy in [L-Au-SR]- complexes (L = H and Au; R = H and CH3)

Thiolate-protected noble-metal clusters play essential roles in numerous applications, rendering this area one of the most vibrant research frontiers. The gold-hydrogen analogy has been firmly established in various hydrogen-atom-doped small gold clusters. In this work, we systematically investigate the chemical bonding characteristics in isolated model systems of [L-Au-SR]- (L = H and Au; R = H and CH3) complexes. By combining gas-phase negative ion photoelectron velocity-map imaging (NI-PEVMI) with density functional theory calculations, we demonstrate that the geometric and frontier molecular orbital properties of Au2SR- (R = H and CH3) closely mimic those of HAuSR- (R = H and CH3), respectively. Furthermore, our analyses reveal that the covalent character of the bonds is ligand-dependent and follows the trend: Au-H > Au-Au > Au-S.