Structural Analysis of the Complexation of Uranyl, Neptunyl, Plutonyl, and Americyl with Cyclic Imide Dioximes

Abstract

Knowledge-based design of extracting agents for selective binding of actinides is essential in stock-pile stewardship, environmental remediation, separations, and nuclear fuel disposal. Robust computational protocols are critical for in depth understanding of structural properties and to further advance the design of selective ligands. In particular, rapid radiochemical separations require predictive capabilities for binding in the gas phase. This study focuses on gas-phase binding preferences of cyclic imide dioximes to uranyl, neptunyl, plutonyl, and americyl. Structural properties, electron withdrawing effects, and their effects on binding preferences are studied with natural bond-order population analysis. The aromatic amidoximes are found to have a larger electron-donation effect than the aliphatic amidoximes. It is also found that plutonyl is more electron withdrawing than uranyl, neptunyl, and americyl when bound to the cyclic imide dioximes studied.

Complexation of Cyclic Glutarimidedioxime with Cerium: Surrogating for Redox Behavior of Plutonium

“…The complexation of glutarimidedioxime has been investigated with a number of metal ions in recent years. − These results suggested the bonding of glutarimidedioxime ligands with metal ions is dominantly electrostatic in nature. − Glutarimidedioxime is a strong π-donor ligand, exhibiting a remarkable affinity for pentavalent vanadium ions with the highest stability constant value . Oxygens of vanadate (VO 2 + ) were cleaved off by glutarimidedioxime through chelation, forming non-oxido V 5+ complexes .…”

Structural Characteristics, Population Analysis, and Binding Energies of [An(NO3)]2+(with An = Ac to Lr)

“…Finally, Dolg and co-workers evaluated the hydration energy across the actinide series through electronic structure calculations, showing an accuracy of the methodologies employed to be within 1% of experimental values; however, there was only experimental data for two actinides (uranium and plutonium) . In some cases, all of these aspects were evaluated for a ligand (cyclic imide dioximes) but only with a small subset of the actinides . Last, we note that the extent of variations in the prediction of these properties for actinide-containing compounds from utilizing different methodologies or levels of theory is often problematic as few methods have been used in systematic studies across the entire actinide series.…”

“…23 In some cases, all of these aspects were evaluated for a ligand (cyclic imide dioximes) but only with a small subset of the actinides. 33 Last, we note that the extent of variations in the prediction of these properties for actinide-containing compounds from utilizing different methodologies or levels of theory is often problematic as few methods have been used in systematic studies across the entire actinide series.…”

“…Three metrics have been advanced across the actinide series for understanding ligand–actinide interactions: population analysis, structural characteristics, and binding energies. Population analysis is a useful aid for the analysis of electron withdrawing effects and their effect on selective binding to actinides. , Mulliken population analysis has been extensively used with uranium compounds, − but this type of analysis is largely dependent on the level of theory of choice, which makes comparisons across different studies uncertain. Structural characteristics include careful comparisons on bond distances and angles between the ligand and actinide.…”

Establishing Cost-Effective Computational Models for the Prediction of Lanthanoid Binding in [Ln(NO3)]2+ (with Ln = La to Lu)

“…The geometry optimizations are performed utilizing DFT following a protocol in previous work, with the B3LYP , functional, the Stuttgart RSC Segmented ECP and associated basis set for the lanthanoid atoms, and the 6-311++G** basis set for O and N atoms with tight tolerances and extra fine grid. The ECP accounts for scalar relativistic effects by replacing 28 electrons with a relativistic pseudopotential.…”