To elucidate the formation mechanism of precious metal deposits, there have been numerous studies on the adsorption mechanism of precious metals onto minerals. From previous studies, the adsorption mechanism of [PdCl4]2- and [AuCl4]- onto minerals is known to be closely related to their ligand substitution. To reveal the relationship, the electronic states for [PdCl4-n(OH)n]2- and [AuCl4-n(OH)n]- (n = 0 - 4) were calculated using the DV-Xα method which is one of the first principle molecular orbital calculation method. The change of ionic properties of each atom caused by the substitution was revealed quantitatively. From the values of a bond overlap population, it was revealed that the electronic polarization of M-O bond (M: Pd or Au) is larger than that of M-Cl bond. Consequently, the adsorption of [PdCl4-n(OH)n]2- and [AuCl4-n(OH)n]- onto minerals may be proceed by the relatively strong electronic polarization of the M-O bond associated with the ligand substitution.
