Infrared Spectra and DFT Calculations for the Gold Hydrides AuH, (H2)AuH, and the AuH3 Transition State Stabilized in (H2)AuH3

Abstract

Reactions of laser-ablated gold atoms with hydrogen (H2, D2, HD) in excess argon and neon and in pure deuterium produced AuH and the (H2)AuH and (H2)AuH3 complexes in increasing yields, respectively, in these matrix hosts. The diatomic molecule AuH absorbs at 2226.6 cm-1 in solid argon, slightly blue shifted from the gas-phase value, and the stable (H2)AuH complex appears at 2173.6 cm-1 on annealing to allow diffusion and association of H2 and AuH. The higher (H2)AuH3 complex presents at 1642.0 cm-1 on deposition. In neon (H2)AuH and (H2)AuH3 give weak bands at 2170 and 1684 cm-1 with D2 counterparts at 1559 and 1207 cm-1, which become strong 1556.5 and 1198.6 cm-1 absorptions in pure deuterium. DFT structure and frequency calculations confirm these assignments and show that the AuH3 transition state with an imaginary b1 bending frequency is stabilized in the (H2)AuH3 complex with a real b1 bending frequency observed at 457.0 cm-1 for (D2)AuD3.