Complex Formation of Nickel(II) and Copper(II) with Barbituric Acid

Abstract

Equilibrium studies have been carried out on complex formation of M 2+ ions (M = Ni and Cu) with L = barbituric acid (BA) in aqueous solution at 25.0 ± 0.1 °C and with an ionic strength of I = 0 . 10 M (KNO 3 ) in aqueous medium. The basicity of the ligand was also assessed by the determination of the dissociation constants of the ligand. The experimental pH titration data were analyzed with the help of the BEST computer program in order to evaluate the stability constants of the various species formed. The stability constants of the binary systems decrease in the order of Cu(II) > Ni(II). Distribution diagrams for the species were drawn showing the concentrations of individual species as a function of pH by the SPE software program.