Tri--butyl Phosphate vs Tri--amyl Phosphate Complexation with Th(IV), U(VI), and Nd(III): From Theory to Experiment.

The complexation behavior of tri--amyl phosphate (TiAP) and tri--butyl phosphate (TBP) ligands with U(VI), Th(IV), and Nd(III) was investigated using density functional theory (DFT). Quantum chemical calculations yielded identical coordination geometries for TBP and TiAP complexes. Calculated complexation energies indicated a preferential extraction of U(VI) followed by Th(IV) over Nd(III), aligning with solvent extraction experiments conducted in the cross-current mode.