Equilibrium studies of mixed-ligand complexes of uranyl ion with mono- and dicarboxylic acids in aqueous solution

Abstract

The stability constants of the ternary UO₂²⁺ complexes involving monobasic acids, propionic, pyruvic and phenoxy acetic acids and secondary ligands were determined by pH titrations. Most of the ternary complexes with the primary ligands, propionic and pyruvic acids, are more stable than one would expect from statistical considerations. The stability values show the discriminating qualities of UO₂²⁺-monobasic acid 1:1 complexes toward the second ligand to be coordinated. The overall stability is found to be dependent on the binary stabilities. The formation of ternary complex is also dependent on the product of acid dissociation constants of the secondary ligands.