Density functional studies of closed-shell attractions of S(AuPH3)2 and HS(AuPH3)2 + and their dimers.

With the help of quantum chemical calculations, S(AuPH3)2, [HS(AuPH3)2]+ and their dimers have been examined by using scalar-relativistic theory. In agreement with experimental data, [HS(AuPH3)2 +]2 is a C(2h) structure. However, [S(AuPH3)2]2 is predicted to favor a D(2d) structure. Experimental structure parameters of the title compounds were reproduced at the Xalpha level. The electronic structure and HOMO-LUMO gaps were investigated. When two monomers formed a dimer, the electronic structure of the dimer changed only slightly, but the chemical stability decreased. The intermolecular aurophilic interaction energy is decomposed and analyzed.