Experimental and theoretical studies on actinide extraction: dibutyl phenyl phosphonate <i>versus</i> tri-<i>n</i>-butyl phosphate

Disale, Shamrao T.; Rao, C. V. S. Brahmmananda; Gopakumar, Gopinadhanpillai; Jayaram, Radha V.

doi:10.1080/00958972.2019.1614175

Cited by 16 publications

(9 citation statements)

References 36 publications

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“…Various possible starting geometries were generated by distributing ligands and nitrate anions around UO 2 2+ . During this step, the metal–ligand stoichiometry was considered to be 1:2 because the same was experimentally estimated for various uranyl nitrate complexes with phosphorus-based ligands. ,,− A straightforward geometry optimization and subsequent characterization of harmonic vibrational frequencies resulted in several local minima on the potential energy hypersurface of each complex. The lowest-energy structures of uranyl nitrate complexes with various substituted phosphinic acid ligands are represented in Figure .…”

Section: Resultsmentioning

confidence: 99%

Insights into the Coordination Behavior of Methyl-Substituted Phosphinic Acids with Actinides

et al. 2022

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The electronic structure and complexation behavior of methylsubstituted phosphinic acids with U(VI) and Pu(IV) were explored by applying quantum chemical methods. In contrast to Ingold's classification, our results indicate that the methyl group is electron-withdrawing, reducing the phosphoryl group electron density in substituted phosphinic acids. The magnitude of the computed complexation energy values increases along with the series, PA → MPA → DMPA, and MP → MMP → MDMP, implying an increasing complexation tendency upon methyl group substitution for both U(VI) and Pu(IV) complexes. One of the nitrate groups in UO 2 (NO 3 ) 2 •2L complexes (L = PA, MPA, and DMPA) is in monodentate coordination mode due to the additional stability gained from O 2 N−O•••H hydrogen bonding interactions with the acidic H atoms of respective ligands. The calculation indicates marginally stronger metal−ligand interactions in Pu(IV) complexes compared to that in U(VI), which is supported by the computed complexation energies, M−O P bond lengths, ν(P�O), the extent of metal−ligand charge transfer, and properties of M−O P bond critical points. The energy landscape of substituted phosphinic acid ligands is further analyzed within the framework of the activation strain model to explain the energetic preference of certain conformers.

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Section: Resultsmentioning

confidence: 99%

Insights into the Coordination Behavior of Methyl-Substituted Phosphinic Acids with Actinides

et al. 2022

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“…The starting geometries were constructed by distributing the ligand molecule around metal nitrate in various possible orientations. This methodology was proven to be effective in the past for identifying the lowest-energy geometries of various actinide metal complexes. − The metal–ligand stoichiometry was considered to be 1:2 as it is the same stoichiometry experimentally estimated for uranyl nitrate complexes with various phosphate and phosphonate ligands (dibutyl phenyl phosphonate (DBPP), TBP, TAP, TiAP, etc. ). , The DFT-derived geometries of the four metal complexes are illustrated in Figure a–d.…”

Section: Results and Discussionmentioning

confidence: 99%

“…This methodology was proven to be effective in the past for identifying the lowest-energy geometries of various actinide metal complexes. − The metal–ligand stoichiometry was considered to be 1:2 as it is the same stoichiometry experimentally estimated for uranyl nitrate complexes with various phosphate and phosphonate ligands (dibutyl phenyl phosphonate (DBPP), TBP, TAP, TiAP, etc. ). , The DFT-derived geometries of the four metal complexes are illustrated in Figure a–d. For all complexes, the lowest-energy structure is geometrically identical, where both ligand units and nitrate groups are located around the metal center in trans-positions.…”

Section: Results and Discussionmentioning

confidence: 99%

On the Nature of the Carbonyl versus Phosphoryl Binding in Uranyl Nitrate Complexes

et al. 2020

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The electronic structure of ligands with phosphoryl and carbonyl binding sites and their complexation behavior with uranyl nitrate were investigated using density functional theory (DFT). The quantum chemical calculations indicate that the electronic charges on both phosphoryl and carbonyl groups are more polarized toward oxygen atoms in isolated ligands. This effect is predominant in the case of complexes of the former. Both PO and CO groups are positively charged with the exception in methylisobutylketone (MIBK), where the C=O group is virtually neutral. The fragment molecular orbital analysis suggests that during complexation, a certain amount of charge transfer occurs from the filled pπ-orbitals [π x (CO/PO) and π y (CO/PO) ] of the ligand to 5f, 6d, and 7s orbitals of the uranium atom (fσ* and dsσ*). The NBO analysis reaffirms the charge transfer mechanism. The observed red shift in ν(CO) and ν(PO) identified in the simulated infrared spectrum of the corresponding complexes implies a moderate weakening of both carbonyl and phosphoryl bonds upon complexation. The atoms in molecules (AIM) analysis suggests a stronger phosphoryl binding compared to carbonyl interactions and an ionic U–O bond. The estimated complexation energies are considerable for phosphoryl ligands compared to those of the carbonyl analogue, with a reasonably large value derived for tri-n-butyl phosphate (TBP). The energy decomposition analysis marked significant stabilizing orbital interactions for phosphoryl ligands. The contributions of estimated dispersion energies are considerable in all complexes and extensively depend on the alkyl unit.

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“…is basis set guarantees its well behavior for U. e CI, CCSD, QCISD (T), and DFT methods are reliable for the investigation of transition metal compounds [18,19]. After the potential energies being obtained, a Morse function was fit as follows:…”

Section: Methodsmentioning

confidence: 99%

Potential Functions and Thermodynamic Properties of UC, UN, and UH

Tang

Wang

Xia

et al. 2020

Journal of Chemistry

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Potential energy surface scanning for UC, UN, and UH was performed by configuration interaction (CI), coupled cluster singles and doubles (CCSD) excitation, quadratic configuration interaction (QCISD (T)), and density functional theory PBE1 (DFT-PBE1) methods in coupling with the ECP80MWB_AVQZ + 2f basis set for uranium and 6 − 311 + G∗ for carbon, hydrogen, and nitrogen. The dissociation energies of UC, UN, and UH are 5.7960, 4.5077, and 2.6999 eV at the QCISD (T) levels, respectively. The calculated energy was fitted to the potential functions of Morse, Lennard-Jones, and Rydberg by using the least square method. The anharmonicity constant of UC is 0.0047160. The anharmonic frequency of UC is 780.27 cm−1 which was obtained based on the PBE1 results. For UN, the anharmonicity constant is 0.0049827. The anharmonic frequency is 812.65 cm−1 which was obtained through the PBE1 results. For UH, the anharmonicity constant is 0.017300. The anharmonic frequency obtained via the QCISD (T) results is 1449.8 cm−1. The heat capacity and entropy in different temperatures were calculated using anharmonic frequencies. These properties are in good accordance with the direct DFT-UPBE1 results (for UC and UN) and QCISD (T) results (for UH). The relationship of entropy with temperature was established.

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Experimental and theoretical studies on actinide extraction: dibutyl phenyl phosphonate versus tri-n-butyl phosphate

Cited by 16 publications

References 36 publications

Insights into the Coordination Behavior of Methyl-Substituted Phosphinic Acids with Actinides

Insights into the Coordination Behavior of Methyl-Substituted Phosphinic Acids with Actinides

On the Nature of the Carbonyl versus Phosphoryl Binding in Uranyl Nitrate Complexes

Potential Functions and Thermodynamic Properties of UC, UN, and UH

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