Plutonium (iv) complexes of mixed pyridine n-oxide and phosphinoxide f-element extractants

Analytical and bulk scale separation and processing of aqueous acidic solution s containing f-element ions are regularly accomplished using liquid-liquid extraction (LLE) methods that employ a neutral organic donor ligand dissolved in an organic phase . 1-5 Several monofunctional ligands have been used as LLE reagents, but all display one or more deficiencies1 'S due to the chemical similarity of the tri valent lanthanides (Ln) to th e trivalent actindes (An) . Since the trivalent 4f and 5f ions have identical charges, chemical separation agents for these two groups need to differentiate among these har d cations based on their size or chemical bonding preferences . This task is not easy since, as a consequence of the lanthanide and actinide contractions, the Ln and An fission products which need to be separated have similar ionic radii . In order to develop new ligands for the separation process, we must have a fundamental understanding of how these separation agents interact with both Ln and An ions on a molecular level.