Crystallization of a Neptunyl Oxalate Hydrate from Solutions Containing NpV and the Uranyl Peroxide Nanocluster U60 Ox30

Uranyl peroxide nanoclusters are an evolving family of materials with potential applications throughout the nuclear fuel cycle. While several studies have investigated their interactions with alkali and alkaline earth metals, no studies have probed their interactions with the actinide elements. This work describes a system containing U₆₀ Ox₃₀ , [((UO₂ )(O₂ ))₆₀ (C₂ O₄ )₃₀ ]^60- , and neptunium(V) as a function of neptunium concentration. Ultra-small and small angle X-ray scattering were used to observe these interactions in the aqueous phase, and X-ray diffraction was used to observe solid products. The results show that neptunium induces aggregation of U₆₀ Ox₃₀ when the neptunium concentration is≤10 mM, whereas (NpO₂ )₂ C₂ O₄  ⋅ 6H₂ O(cr) and studtite ultimately form at 15-25 mM neptunium. The latter result suggests that neptunium coordinates with the bridging oxalate ligands in U₆₀ Ox₃₀ , leaving metastable uranyl peroxide species in solution. This is an important finding given the potential application of uranyl peroxide nanoclusters in the recycling of used nuclear fuel.

Use of vibrational spectroscopy to identify the formation of neptunyl-neptunyl interactions: A paired Density Functional Theory and Raman spectroscopy study

Abstract: Actinyl-Actinyl interactions (AAIs) occur in pentavalent actinide systems, particularly for Np(V), and lead to complex vibrational signals that are challenging to analyze and interpret. Previous studies have focused on...

Diboron Bonds Between BX3 (X=H, F, CH3 ) and BYZ2 (Y=H, F; Z=CO, N2 , CNH)

The ability of B atoms on two different molecules to engage with one another in a noncovalent diboron bond is studied by ab initio calculations. Due to electron donation from its substituents, the trivalent B atom of BYZ₂ (Z=CO, N₂ , and CNH; Y=H and F) has the ability to in turn donate charge to the B of a BX₃ molecule (X=H, F, and CH₃ ), thus forming a B⋅⋅⋅B diboron bond. These bonds are of two different strengths and character. BH(CO)₂ and BH(CNH)₂ , and their fluorosubstituted analogues BF(CO)₂ and BF(CNH)₂ , engage in a typical noncovalent bond with B(CH₃ )₃ and BF₃ , with interaction energies in the 3-8 kcal/mol range. Certain other combinations result in a much stronger diboron bond, in the 26-44 kcal/mol range, and with a high degree of covalent character. Bonds of this type occur when BH₃ is added to BH(CO)₂ , BH(CNH)₂ , BH(N₂ )₂ , and BF(CO)₂ , or in the complexes of BH(N₂ )₂ with B(CH₃ )₃ and BF₃ . The weaker noncovalent bonds are held together by roughly equal electrostatic and dispersion components, complemented by smaller polarization energy, while polarization is primarily responsible for the stronger ones.

Speciation analysis the complexation of uranyl nitrate with tri-n-butyl phosphate in supercritical CO2

The complexation of solid uranyl nitrate with tri-n-butyl phosphate (TBP) in supercritical CO₂ is quite different from that of a liquid–liquid extraction system because fewer water molecules are involved. Here, the complexation mechanism was investigated by molecular dynamics simulation, emphasising on speciation distribution analysis. In the anhydrous uranyl nitrate system, poly-core uranyl-TBP species [UO₂(NO₃)₂]₂·3TBP and [UO₂(NO₃)₂]₃·3TBP were formed in addition to the predominant [UO₂(NO₃)₂]·1TBP and [UO₂(NO₃)₂]·2TBP species. The poly-core species was mainly constructed via the linkage of U Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O⋯U contributed by pre-developed [UO₂(NO₃)₂]·1TBP species. However, in the hydrated uranyl nitrate system, TBP·[UO₂(NO₃)₂]·H₂O species form, preventing the formation of the poly-core species. The complexation developed differently depending on the TBP to the uranyl nitrate ratio, the solute densities and the participation of water. It suggested that the kinetically favoring species would gradually convert into the thermodynamically stable species [UO₂(NO₃)₂]·2TBP by ligand exchange.

Uranyl nitrate complex with TBP in supercritical CO₂ could form 1 : 1 and 1 : 2 species, and further generate 2 : 3 and 3 : 3 poly-core uranyl species.

Trimeric uranyl(vi)-citrate forms Na+, Ca2+, and La3+ sandwich complexes in aqueous solution

M. Basile, et al., Chem. Commun., 2015, 51, 5306-5309, showed that a sodium ion is sandwiched by uranyl(vi) oxygen atoms of two 3 : 3 uranyl(vi)-citrate complex molecules in single-crystals. By means of NMR spectroscopy supported by DFT calculations we provide unambiguous evidence for this complex to persist in aqueous solution above a critical concentration of 3 mM uranyl citrate. Unprecedented Ca²⁺ and La³⁺ coordination by a bis-(η³-uranyl(vi)-oxo) motif advances the understanding of uranium's aqueous chemistry. As determined from ¹⁷O NMR, Ca²⁺ and more distinctly La³⁺ cause strong O[double bond, length as m-dash]U[double bond, length as m-dash]O polarization, which opens up new ways for uranyl(vi)-oxygen activation and functionalization.