Related Experiment Video
Updated: Jan 16, 2026

Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films
Published on: November 9, 2015
Theoretical Study on Coordination Chemistry of Two Water-Soluble Ligands for Stripping Separation of Transplutonium
Pin-Wen Huang1, Peng Ren2, Ming Qi3
1Nanxun Innovation Institute, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310000, China.
Abstract:
Purification and mutual separation of trivalent actinides (An3⁺: Am, Cm, Bk, Cf) present significant challenges in nuclear waste treatment. Elucidating complexation mechanisms with stripping ligands is crucial for ligand development. Given the radiotoxicity, quantum chemical methods are essential. This DFT study investigates chelation of An3⁺ ions with water-soluble ligands H2L2ᵖʸ and H2L2ᵖᶻ. Probable back-extraction complexes ([AnLi(H2O)ⱼ]⁺, AnLi(NO3)(H2O)k) exhibit near-identical geometries with minor An─O/N bond length variations. Analyses reveal enhanced chelating ability for diamine N atoms adjacent to carboxylate O versus N-heterocyclic donors (pyridine/pyrazine). Crucially, interaction intensity and partial covalency between An3⁺ and donor atoms (NAM, OCA, NPY/PZ) display a distinct bimodal variation with Cm as the turning point. This trend likely originates from closer orbital energy matching between the 5f orbitals of Am/Bk/Cf and ligand 2p orbitals compared to Cm. Thermodynamic analyses demonstrate superior back-extraction ability for H2L2ᵖʸ, while H2L2ᵖᶻ excels in Am/Eu separation. The downward-upward trend in reaction free energies aligns with covalency variations, suggesting potential intra-group separation capability for all four ions. Estimated separation factors SFAm/Cm, SFBk/Cm, and SFCf/Cm are projected within 2.45-3.45.
Related Concept Videos
Extraction: Advanced Methods
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Complexometric Titration: Ligands
Coordination Compounds and Nomenclature
Valence Bond Theory
EDTA: Chemistry and Properties

