Influence of complexing species on the extraction of trivalent actinides from lanthanides with CyMe4–BTBP: a theoretical study

Abstract

We studied geometric and electronic structures as well as thermodynamic properties of complexes [M(CyMe4–BTBP)2(NO3)]2+ and [M(CyMe4–BTBP)2]3+ with M = Am(III), Cm(III) and Ln(III) (La–Lu) theoretically. The actinide–nitrogen bonding is principally ionic with higher covalency in An–N bonds than in the Ln–N analogues. The selectivity towards An(III) over Ln(III) (La, Ce, Pr, Pm, Sm, Eu and Yb) is influenced by formed complexes to different extents by comparison of changes of Gibbs free energy of reaction, ΔΔGAm/Ln, for formation of [AmL2]3+/[LnL2]3+, [AmL2(NO3)]2+/[LnL2(NO3)]2+, and [AmL2(NO3)]2+/[LnL2]3+. The Am(III) selectivity is enhanced for [AmL2(NO3)]2+/[LnL2]3+ over [AmL2]3+/[LnL2]3+.