Liquid–liquid distribution studies on moderately labile metal chelates. Kinetics of hydrolysis of tris(thenoyltrifluoroacetonate)thallium(III)

Abstract

Summary Kinetics of hydrolysis of tris(thenoyltrifluoroacetonate)thallium(III) in water was studied by back extraction of this moderately labile metal chelate, labelled with 204Tl, from a water-immiscible organic solvent to aqueous solutions. A function of the distribution ratio of the metal was derived, which linearly depended on time after reaching quasi-equilibrium of chelate partition. Its extrapolation to zero time made it possible to evaluate the partition constant of the chelate. The rate constant of its hydrolysis was determined from the slope. The dependence of the rate constant on pH and on the ligand concentration shows that both acid and base hydrolysis of the chelate studied took place. The approach used can be helpful for determining partition constants of moderately labile metal complexes and the lability of the complexes in aqueous solutions.