Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

摘要

Solution equihbna of the binary and ternary complex systems of the divalent transition metal ipns Cu , Ni~(2+) Zn~(2+), and Co~(2+)with 1,2,4-triazole (TRZ), 3-mercapto-l,2,4-triazole (TRZSH), and 3-amino-l,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) ℃, and a constant ionic strength 1=1×10~(-1) mol L~(-1) NaNO_3 in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of A log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu~(2+) Ni~(2+), and Co~(2+) has been studied along with the corresponding ther-modynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectropho-tometry.