Thermodynamics of complex formation of Ag(I): XI. Systems Ag(I)–thiocarbonyl bidentate ligands in aqueous solution

Complex formation in aqueous solution between Ag(I) and dithioxamide, thiobiuret, dithiobiuret, 2-thiouracil, 4-propyl-2-thiouracil, acetyl-thiourea were investigated by potentiometry at T=278.2–318.2 K and ionic strength μ=0. The formation of mono-coordinate AgL complexes in the systems Ag(I)–dithioxamide, Ag(I)–thiobiuret and Ag(I)–acetyl-thiourea, the stepwise formation of di-cordinate AgLn (n=1,2) complexes in the system Ag(I)–4-propyl-2-thiouracil and the stepwise formation of three-coordinate AgLn (n=1–3) complexes in the systems Ag(I)–dithiobiuret and Ag(I)–thiobiuret have been found. The standard ΔHn0 and ΔSn0 values were deduced from the dependence of ΔGn0 on temperature. The values of ΔH10 and ΔS10 for the series of complex reactions Ag(I)+L(i)=AgL(i) are linearly related to each-other. The evaluated isoequilibrium temperature is Tiso=294 K. The influence of the coordinated ligand on the subsequent ligand coordination in the stepwise complex formation reactions is discussed.