Study of Complexation Processes in the Cu(Hg)–Cu(II)–L-Val–H2O System Using the Potentiometry Method

The processes of formation of complexes of L– valine with the Cu2+ ion at temperatures of 288.15, 298.15, 308.15, and 318.15 K and ionic strength of the solution (NaNO3)I = 1.00 mol/L are studied. The composition is identified and the step constants of complex formation are calculated. It is shown that with increasing temperature, the stability of the complexes decreases. It is established that the following coordination compounds are formed in this system: [CuL(H2O)3]+; [CuHL(H2O)3]2+; [CuL2(H2O)2]0; [CuL(OH)(H2O)2]0; [CuL(OH)2(H2O)]–; and [CuL(OH)3(H2O)0]2–. Using the method of successive approximation (iteration) of the oxidation function, the constants of complex formation are calculated, the areas of their dominance and maximum degrees of accumulation are determined, and diagrams of their distribution with respect to pH are constructed.