Complexation thermodynamics and the structure of the binary and the ternary complexes of Am 3+, Cm 3+ and Eu 3+ with IDA and EDTA + IDA

Abstract

The stability and the associated thermodynamic parameters of the binary and the ternary complexes of trivalent Am, Cm, and Eu with IDA and with EDTA + IDA, were determined by using a solvent extraction technique for aqueous solutions of I = 6.60 m (NaClO 4) at temperatures of 0–60 °C. The endothermic enthalpy and the positive entropy reflect the significant effect of dehydration in the formation of these complexes at high ionic strength. TRLFS and NMR ( 1H and 13C) data helped to establish the structure of the ternary complexes in solution. In the ternary complex M(EDTA)(IDA) 3−, EDTA binds via four carboxylates and two nitrogens, and IDA via two carboxylates and one nitrogen to the central Eu 3+.