Uranyl complexes with nitrogen and sulfur donor bidentate ligands: a computational modeling of coordination geometries, thermodynamic parameters, and ligand substituent effects

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Patrick Bailey Hogsed (Creator)
Western Carolina University (WCU )
Web Site: http://library.wcu.edu/
Channa DeSilva

Abstract: Actinides represent a special group of metal ions that need to be extensively studied due to their presence in the environment with the construction of nuclear power plants, processing of minerals, and weapon production. Radioactive waste produced by nuclear fission contains several lanthanide and actinide metals, including uranium. The extraction of uranium from nuclear waste is an active area of research. To this end, numerous sulfur and nitrogen-donor ligands have been studied to assist with the nuclear extraction process. Computational chemistry investigations of actinide complexes will provide important insight into metal-ligand bonding and their thermodynamic properties in order to design effective actinide extracting agents. Current research work is focused on studying the coordination chemistry behavior and reaction energetics of a series of uranyl metal complexes with ethylenediamine, 1,2-ethanedithiol, and cysteamine ligands using density functional theory (DFT). Coordination preferences using nitrogen and sulfur-based chelation were evaluated in the gas phase. Nitrogen donor ethylenediamine ligand produced the lowest reaction Gibbs free energies, and sulfur donor cysteamine ligands had the highest values. Ligand substitution effects on uranyl metal-ligand bonding were studied using four substituent groups, CH3, CN, OCH3, and Cl. Electron donor CH3 and OCH3 groups provided relatively shorter metal-ligand bond distances and lower reaction Gibbs free energies. Electron withdrawing substituents resulted in longer metal-ligand bonding and higher reaction Gibbs free energies. Disubstitution of the chelating ligands amplifies the above effects. Future work will focus on exploring more substituents and solvent effects on uranyl metal-ligand complexation reaction using the above ligands.

Additional Information

Language: English
Date: 2021
Computational chemistry, Inorganic chemistry, Nuclear waste extraction
Chemistry, Inorganic
Computational chemistry
Radioactive waste disposal

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