COMPLEXATION OF THE URANYL-ION (UO22+) WITH PHENYLENE-1,2-DIOXYDIACETIC ACID

Complexation of uranyl cations by phenylene-l,2-dioxydiacetic acid has been studied by potentiometry, calorimetry, solvent extraction, and 1H NMR spectroscopy. Complexation parameters at 298 K and 0.1 M (ÑaClO4) ionic strength are as follows: log β101 = 3.01 ± 0.05; log β111 = 5.22 ± 0.04; ΔH101 = 16.8 ± 0.2 kJ mol-1; ΔS101 = 114 ± 5 J K-1 mol-1; ΔH111 = 10.4 ± 0.5 kJ mol-1; ΔS111 = 68 ± 5 J K-1 mol-1. The thermodynamic and NMR data are consistent with bonding of UO22+ to the carboxylate groups of the ligand, with weak or no interaction with the ether oxygens. No 1:2 complexation was observed. © 1990, American Chemical Society. All rights reserved.