The Hydrolysis of AuCl4− and the Stability of Aquachlorohydroxocomplexes of Gold(III) in Aqueous Solution

The equilibria AuCl4−+jOH−+kH2O⇌AuCl4−j−k(OH)j(H2O)kk−1+(j+k)Cl−, βjk (0≤j,k≤4) have been studied spectrophotometrically at 20 °C in aqueous solution. For I=2 mol⋅dm−3(HClO4) the conventional constants, βi*, of the equilibria, Au*+iCl−⇌AuCli*, are equal to log 10β1*=(6.98±0.08); log 10β2*=(13.42±0.05); log 10β3*=(19.19±0.09); and log 10β4*=(24.49±0.07), where [AuCli*]=∑[AuCli(OH)j(H2O)4−i−j] at i=const. The hydrolysis and other transformations of AuCl4− in aqueous solution are discussed. On the basis of new and known data, a full set of equilibrium constants, βjk, or their estimates has been obtained.