Extraction of actinides by Tri-n-butyl phosphate derivatives: Effect of substituents

Annam, Suresh; Gopakumar, Gopinadhanpillai; Rao, C. V. S. Brahmmananda; Sivaraman, N.; Sivaramakrishna, Akella; Vijayakrishna, Kari

doi:10.1016/j.ica.2017.07.048

Cited by 24 publications

(9 citation statements)

References 34 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%

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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%

“…65, +0.83, and +0.99e, respectively) and MP → MMP → MDMP (+0.60, +0.85, and +1.01e, respectively). Note that for both the series, methyl groups progressively substitute the H atoms, and the electron density at the P atom is subsequently reduced due to the electronegative nature of C atoms.…”

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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%

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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“…32,33 The classic examples include long-chain amides of n-octyl(phenyl)(N,N-diisobutylcarbamoyl)methyl phosphine oxide (CMPO), tri-butyl phosphate (TBP) and N,N,N,N-tetraoctyl diglycolamide (TODGA) as extractants for the selective recovery of actinide ions from matrix constituents. [34][35][36][37][38] The derivative of TODGA has been extensively used for analyzing the extraction behavior of various f-block elements, as these aliphatic amides were found to bind the targets strongly with reasonable stability. An ion-pair HPLC technique has been reported by Sivaraman et al for the individual isolation of Lns from uranium, plutonium, and other ssion products where the preseparation of Ln-ssion products has been achieved using di-(2ethylhexyl) phosphoric acid coated Amberlite XAD-7 packed bead glass column, using camphor-10-sulfonic acid and a-hydroxy isobutyric acid as the mobile phases.…”

Section: Introductionmentioning

confidence: 99%

Fast and selective reversed-phase high performance liquid chromatographic separation of UO₂²⁺ and Th⁴⁺ ions using surface modified C₁₈ silica monolithic supports with target specific ionophoric ligands

et al. 2023

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Extraction of actinides by Tri-n-butyl phosphate derivatives: Effect of substituents

Cited by 24 publications

References 34 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

Fast and selective reversed-phase high performance liquid chromatographic separation of UO₂²⁺ and Th⁴⁺ ions using surface modified C₁₈ silica monolithic supports with target specific ionophoric ligands

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Extraction of actinides by Tri-n-butyl phosphate derivatives: Effect of substituents

Cited by 24 publications

References 34 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

Fast and selective reversed-phase high performance liquid chromatographic separation of UO22+ and Th4+ ions using surface modified C18 silica monolithic supports with target specific ionophoric ligands

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Fast and selective reversed-phase high performance liquid chromatographic separation of UO₂²⁺ and Th⁴⁺ ions using surface modified C₁₈ silica monolithic supports with target specific ionophoric ligands