Theoretical Study on the Dissolution Reaction of Gold

Abstract

It is well known that gold can be dissolved in aqua regia. Recently, reversible dissolution/deposition of gold was reported in organic solvent with excessive iodine. In both reactions, gold exists in the form of gold halides (AuX2-, AuX4-, X = Cl, Br, I). To examine the geometries and electronic structures of gold halides, which is closely related to the dissolution/deposition reactions, MP2, CCSD(T) and B3LYP calculations were carried out using relativistic effective core potentials (RECPs). Optimized geometric parameters of linear triatomic anions of gold halides and polyhalides are compared with the experimental data. There is not much difference in the calculated bond lengths between MP2, CCSD(T) and B3LYP. Atoms at the edge have negative charge in the gold halides as well as in the polyhalides. Pentatomic anions of gold halides and polyhalides had three local minima on the potential energy surface, with V-shaped, T-shaped and square-planar geometries. Studies on electronic structures and reaction mechanisms involving pentatomic anions are in progress.