Temperature dependence of chloride complexation for the trivalent f-elements

The influence of elevated temperatures on the formation of 1:1 chloro complexes for Eu3+ and Am3+ are reported. Using a solvent extraction technique, stability constants for the equilibrium M(aq)3+ + Cl(aq)- ↔ MCl(aq)2+ have been measured in the temperature range of 25-75 deg C. Modest increases in β1 are observed, and small positive enthalpies for these reactions are reported. These data are discussed in the context of previous reports for the trivalent lanthanide and actinide chloro systems. (author)