Potentiometric determination of stability constants of ternary complexes of first row transition metal ions with ditopic azelaic acid dihydrazide and aspartic acid in aqueous medium

A Chemical speciation study of ternary complexes containing transition metal ions (Mn2+,Co2+,Ni2+, Cu2+ and Zn2+) with a ditopic novel ligand L = Azelaic acid dihydrazide (AZDH) and X = L-Aspartic acid of type [MmLlXxHh], (where m = 1, 2; l = 1; x = 1, 2 and h = -2 to 5) in different ratios of M:L:X = 1:1:1, 1:2:1, 2:1:1and 2:1:2 was carried out using pH -potentiometric method of data acquisition and applied to chemometric modelling methods of analysis. MINIQUAD-75 program was used for the resolution of the plausible species and their corresponding formation constants at 303 +/- 0.1 K, and 0.01 M ionic strength. Species concentration distribution diagrams were generated using HySS program. Best-fit chemical models were selected on the basis of statistical parameters like Standard deviation (SD), U (sum of the squares of the residuals in mass balance equations), and chi-square test etc. Relatively stable ternary complexes were evaluated quantitatively using Delta log K formulation. All the formation constants for the species were compared for Irving-Williams order of stability.