Theoretical Gibbs free energy study on UO2(H2O)n2+ and its hydrolysis products

Tsushima, Satoru; Yang, Tianxiao; Suzuki, Atsuyuki

doi:10.1016/s0009-2614(00)01470-6

Cited by 74 publications

(97 citation statements)

References 28 publications

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“…Over the years various computational studies on model systems, with or without the inclusion of an approximate description of the molecule's environment, have been reported in the literature. [1][2][3][4][5][6][7] For example, in our recent computational modeling study of gas-phase uranyl carbonate, nitrate, and acetate complexes 8 we showed that the calculated structures and vibrational frequencies are in generally good agreement with experimental data obtained in the solution and solid-state environment.…”

Section: Introductionsupporting

confidence: 55%

Density Functional Studies on the Complexation and Spectroscopy of Uranyl Ligated with Acetonitrile and Acetone Derivatives

2009

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The coordination of nitrile (acetonitrile, propionitrile, and benzonitrile) and carbonyl (formaldehyde, acetaldehyde, and acetone) ligands to the uranyl dication (UO22+) has been examined using density functional theory (DFT) utilizing relativistic effective core potentials (RECPs). Complexes containing up to six ligands have been modeled in the gas phase for all ligands except formaldehyde, for which no minimum could be found. A comparison of relative binding energies indicates that 5-coordinate complexes are predominant, while 6-coordinate complexes involving propionitrile and acetone ligands might be possible. Additionally, the relative binding energy and the weakening of the uranyl bond is related to the size of the ligand, and in general, nitriles bind more strongly to uranyl than carbonyls. Disciplines Chemistry CommentsReprinted (adapted) The coordination of nitrile (acetonitrile, propionitrile, and benzonitrile) and carbonyl (formaldehyde, acetaldehyde, and acetone) ligands to the uranyl dication (UO 2 2+ ) has been examined using density functional theory (DFT) utilizing relativistic effective core potentials (RECPs). Complexes containing up to six ligands have been modeled in the gas phase for all ligands except formaldehyde, for which no minimum could be found. A comparison of relative binding energies indicates that 5-coordinate complexes are predominant, while 6-coordinate complexes involving propionitrile and acetone ligands might be possible. Additionally, the relative binding energy and the weakening of the uranyl bond is related to the size of the ligand, and in general, nitriles bind more strongly to uranyl than carbonyls.

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Section: Introductionsupporting

confidence: 55%

Density Functional Studies on the Complexation and Spectroscopy of Uranyl Ligated with Acetonitrile and Acetone Derivatives

2009

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“…above pH 5 [59,60]. These species are also the likely precursors of uranium oligomers such as (UO 2 ) 2 (OH) 2 2+ that form in solution and as such can be used in future studies of uranium polymerization reactions.…”

Section: Resultsmentioning

confidence: 99%

Quantum mechanical calculation of aqueuous uranium complexes: carbonate, phosphate, organic and biomolecular species

Kubicki

Halada

Jha

et al. 2009

Chemistry Central Journal

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Background: Quantum mechanical calculations were performed on a variety of uranium species representing U(VI), U(V), U(IV), U-carbonates, U-phosphates, U-oxalates, U-catecholates, Uphosphodiesters, U-phosphorylated N-acetyl-glucosamine (NAG), and U-2-Keto-3-doxyoctanoate (KDO) with explicit solvation by H 2 O molecules. These models represent major U species in natural waters and complexes on bacterial surfaces. The model results are compared to observed EXAFS, IR, Raman and NMR spectra.

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“…Actinyl complexes in aqueous solution, particularly those at low pH, have been studied experimentally [1][2][3][4][5][6][7][8][9][10][11][12][13] and theoretically. [13][14][15][16][17][18][19][20][21][22][23] The actinyl ions exist in different oxidation states in the environment but UO 2 2+ , NpO 2 + , and PuO 2 2+ are the most abundant and thus the complexes formed by these species under different pH conditions are of considerable interest. In particular at higher pH values these species form hydroxide complexes and thus their hydrolysis in solution is of particular interest.…”

Section: Introductionmentioning

confidence: 99%

“…36,39 They concluded that while their results for actinide may be reflective of the overall absolute errors in combination of electronic structure and solvation models, calculations of this type should be able to predict relative energies among a series of molecules. Tsushima et al 17 have shown that both temperature and pressure significantly changed the equilibrium constants of actinyl hydrolysis reactions. Molecular dynamics calculations were carried out in order to investigate the hydration structure of uranyl in aqueous solution by these authors.…”

Section: Introductionmentioning

confidence: 99%

Theoretical studies of UO2(OH)(H2O)n+, UO2(OH)2(H2O)n, NpO2(OH)(H2O)n, and PuO2(OH)(H2O)n+ (n≤21) complexes in aqueous solution

Cao

Balasubramanian

2009

The Journal of Chemical Physics

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Extensive ab initio calculations have been carried out to study equilibrium structures, vibrational frequencies, and the nature of chemical bonds of hydrated UO(2)(OH)(+), UO(2)(OH)(2), NpO(2)(OH), and PuO(2)(OH)(+) complexes that contain up to 21 water molecules both in first and second hydration spheres in both aqueous solution and the gas phase. The structures have been further optimized by considering long-range solvent effects through a polarizable continuum dielectric model. The hydrolysis reaction Gibbs free energy of UO(2)(H(2)O)(5) (2+) is computed to be 8.11 kcal/mol at the MP2 level in good agreement with experiments. Our results reveal that it is necessary to include water molecules bound to the complex in the first hydration sphere for proper treatment of the hydrated complex and the dielectric cavity although water molecules in the second hydration sphere do not change the coordination complex. Structural reoptimization of the complex in a dielectric cavity seems inevitable to seek subtle structural variations in the solvent and to correlate with the observed spectra and thermodynamic properties in the aqueous environment. Our computations reveal dramatically different equilibrium structures in the gas phase and solution and also confirm the observed facile exchanges between the complex and bulk solvent. Complete active space multiconfiguration self-consistent field followed by multireference singles+doubles CI (MRSDCI) computations on smaller complexes confirm predominantly single-configurational nature of these species and the validity of B3LYP and MP2 techniques for these complexes in their ground states.

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Theoretical Gibbs free energy study on UO2(H2O)n2+ and its hydrolysis products

Cited by 74 publications

References 28 publications

Density Functional Studies on the Complexation and Spectroscopy of Uranyl Ligated with Acetonitrile and Acetone Derivatives

Density Functional Studies on the Complexation and Spectroscopy of Uranyl Ligated with Acetonitrile and Acetone Derivatives

Quantum mechanical calculation of aqueuous uranium complexes: carbonate, phosphate, organic and biomolecular species

Theoretical studies of UO2(OH)(H2O)n+, UO2(OH)2(H2O)n, NpO2(OH)(H2O)n, and PuO2(OH)(H2O)n+ (n≤21) complexes in aqueous solution

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