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Interactions between the Li+ cation and the neptunyl(vi) oxo observed in both solid state and aqueous solutions.

Crystallization of neptunyl(v) tetrachlorides over neptunyl(vi) species occurs simultaneously with charge assisted hydrogen bonding in our solid state materials, which we explored by DFT calculations, cyclic voltammograms, and Raman spectroscopy.

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...

Solid-state uranyl hybrid structures are often formed through unique intermolecular interactions occurring between a molecular uranyl anion and a charge-balancing cation. In this work, solid-state structures of the uranyl tetrachloride anion engaged in uranyl–cation and uranyl–hydrogen interactions were studied using density functional theory (DFT). As most first-principles methods used for systems of this type focus primarily on the molecular structure, we present an extensive benchmarking study to understand the methods needed to accurately model the geometric properties of these systems. From there, the electronic and vibrational structures of the compounds were investigated through projected density of states and phonon analysis and compared to the experiment. Lastly, we present a DFT + thermodynamics approach to calculate the formation enthalpies (ΔH f) of these systems to directly relate to experimental values. Through this methodology, we were able to accurately capture trends observed in experimental results and saw good quantitative agreement in predicted ΔH f compared to the value calculated through referencing each structure to its standard state. Overall, results from this work will be used for future combined experimental and computational studies on both uranyl and neptunyl hybrid structures to delineate how varying intermolecular interaction strengths relates to the overall values of ΔH f.

The syntheses and crystal structures of six new heterometallic compounds containing the UO cation, o-, m-, and p-iodobenzoic acid ligands, and Tl, Rb, and Cs cations which adopt the role of both charge balancing cation and secondary metal center are described, as are the luminescent properties for Tl containing compounds 1, 4, and 6. The structures of compounds 1-3 are isomorphous and contain uranyl monomers bound by o-iodobenzoic acid ligands with Tl, Rb, and Cs cations acting as secondary metal centers. Compounds 4 and 5 are also isomorphous and feature m-iodobenzoic acid ligands bound to the uranyl cation along with Tl and Rb cations. Compound 6 is unique in this series as it is assembled from a dimeric uranyl unit and features p-iodobenzoic acid ligands and Tl cations which function as charge balancing secondary metal centers. Single crystal X-ray diffraction analysis of these materials suggests that the secondary metal cations are incorporated based on the size of their ionic radius (Tl < Rb < Cs), which is directly related to the size of the "pocket" observed in 1-6. Further, Voronoi-Dirichlet tessellation and Hirshfeld surface analysis were used to probe the coordination environment of the secondary metal centers as part of ongoing efforts to develop metrics for determining the coordination number of secondary metal cations in similar systems.

Hydrogen bonding networks within hexavalent uranium materials are complex and may influence the overall physical and chemical properties of the system. This is particularly true if hydrogen bonding takes places between the donor and the oxo group associated with the uranyl cation (UO 2 2+ ). In the current study, we evaluate the impact of charge-assisted hydrogen bonding on the vibrational modes of the uranyl cation using uranyl tricarbonate [UO 2 (CO 3 ) 3 ] 4– interactions with [Co(NH 3 ) 6 ] 3+ as the model system. Herein, we report the synthesis and structural characterization of five novel compounds, [Co(NH 3 ) 6 ]Cl(CO 3 ) ( Co_Cl_CO 3 ), [Co(NH 3 ) 6 ] 4 [UO 2 (CO 3 ) 3 ] 3 (H 2 O) 11.67 ( Co4U3 ), [Co(NH 3 ) 6 ] 3 [UO 2 (CO 3 ) 3 ] 2 Cl (H 2 O) 7.5 ( Co3U2_Cl ), [Co(NH 3 ) 6 ] 2 [UO 2 (CO 3 ) 3 ]Cl 2 ( Co2U_Cl ), and [Co(NH 3 ) 6 ] 2 [UO 2 (CO 3 ) 3 ]CO 3 ( Co2U_CO 3 ), which contain differences in the crystalline packing and extended hydrogen bonding networks. We show that these slight changes in the supramolecular assembly and hydrogen bonding networks result in the modification of modes as observed by infrared and Raman spectroscopy. We use density functional theory calculations to assign the vibrational modes and provide an understanding about how uranyl bond perturbation and changes in hydrogen bonding interactions can impact the resulting spectroscopic signals.

Oxo group activation with reduction of neptunyl(vi) and plutonyl(vi) to tetravalent hydroxo species by the hydroxypyridinone siderophore derivative 3,4,3-LI-(1,2-HOPO) was investigated in the gas-phase via electrospray ionization mass spectrometry, in solution via Raman spectroscopy, and computationally via density functional theory. Dissociation of the gas-phase tetravalent complexes resulted in actinide-hydroxo bond cleavage.