Complexation of thorium(iv) with acetate at variable temperatures

Abstract

The complexation between Th(IV) and acetate in 1.05 mol kg⁻¹ NaClO₄ was studied at variable temperatures (10, 25, 40, 55 and 70 °C). The formation constants of five successive complexes, Th(Ac)_j^(4−j)+ where Ac = CH₃COO⁻ and j = 1–5, and the molar enthalpies of complexation were determined by potentiometry and calorimetry. Extended X-ray absorption fine structure spectroscopy (EXAFS) provided additional information on the complexes in solution. The effect of temperature on the stability of the complexes is discussed in terms of the electrostatic model.