A monoclinic polymorph of uranyl dinitrate trihydrate, [UO2(NO3)2(H2O)2]·H2O

Shuvalov, Robert R.; Burns, Peter C.

doi:10.1107/s0108270103012113

Cited by 13 publications

(7 citation statements)

References 3 publications

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“…On the other hand, the U−O eq (bi−NO 3 ) and U−N distances become longer by degrees with the increase in HNO 3 concentration. Although the reported crystal structures for uranyl nitrate hydrate compounds show somewhat scattered values, the interatomic distances calculated for the aqueous U VI −NO 3 − species are in agreement with those observed in the crystal structure (i.e., R (U−O ax ) = 1.74−1.76 Å, R (U−O eq (H 2 O)) = 2.40−2.45 Å, and R (U−O eq (bi-NO 3 ) = 2.49−2.54 Å, respectively). , …”

Section: Resultssupporting

confidence: 55%

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

et al. 2009

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In order to elucidate the uranium solution chemistry at the high HNO(3) concentrations typically employed for the reprocessing of spent nuclear fuels, speciation and complex structures of U(IV) and U(VI) are studied in aqueous HNO(3) solutions, as well as in HClO(4) solutions, by means of UV-visible-near-infrared and X-ray absorption spectroscopies and density functional theory calculations. In 1.0 M HClO(4), U(IV) exists as a spherical cation of U(4+), which is surrounded by 9-10 water molecules in the primary coordination sphere, while it forms a colloidal hydrous oxide, U(IV)O(2) x nH(2)O, at a lower acidic concentration of 0.1 M HClO(4). U(VI) exists as a transdioxo uranyl cation, UO(2)(2+), and forms a 5-fold pure hydrate complex of [U(VI)O(2)(H(2)O)(5)](2+) in 1.0 M HClO(4). With increasing HNO(3) concentration, the water molecules of the U(IV) and U(VI) hydrate complexes are successively replaced by planar bidentate coordinating nitrate ions (NO(3)(-)), forming dominant species of [U(IV)(H(2)O)(x)(NO(3))(5)](-) in 9.0 M HNO(3) and [U(VI)O(2)(NO(3))(3)](-) in 14.5 M HNO(3), respectively. The present multitechnique approach also suggests the formation of two intermediate U(VI) species, a 5-fold mononitrato complex ([U(VI)O(2)(H(2)O)(3)(eta(2)-NO(3))](+)) and a 6-fold dinitrato complex ([U(VI)O(2)(H(2)O)(2)(eta(2)-NO(3))(2)](0)), involving an increase in the total coordination number on the uranyl(VI) equatorial plane from 5 to 6 with increasing HNO(3) concentration. The presence of unidentate coordinate nitrato complexes or tetranitrato U(VI) complexes is less probable in the present HNO(3) system.

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Section: Resultssupporting

confidence: 55%

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

et al. 2009

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“…In the di-aquo complexes (Figure ), the U−OH 2 bond lengths are nearly identical, at 2.561 and 2.552 Å, respectively, with comparably short O···H contacts in both cases (2.352 and 2.428 Å, respectively). In Table , we compare the experimental data for UO 2 (NO 3 ) 2 (H 2 O) 2 obtained from neutron and X-ray diffraction with our computational results. − The average experimental (overall structures ± standard deviation) UO, U−O nitrate , and U−OH 2 bond distances are 1.742 ± 0.029, 2.501 ± 0.022, and 2.439 ± 0.026 Å, respectively. The calculated UO and U−O nitrate (2.484 Å) distances are within the experimental error bars, but the average U−OH 2 distance is noticeably longer than the average experimental value by 0.113 Å.…”

Section: Resultsmentioning

confidence: 95%

Interactions of 1-Methylimidazole with UO₂(CH₃CO₂)₂ and UO₂(NO₃)₂: Structural, Spectroscopic, and Theoretical Evidence for Imidazole Binding to the Uranyl Ion

et al. 2006

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The first definitive high-resolution single-crystal X-ray structure for the coordination of the 1-methylimidazole (Meimid) ligand to UO2(Ac)2 (Ac = CH3CO2) is reported. The crystal structure evidence is confirmed by IR, Raman, and UV-vis spectroscopic data. Direct participation of the nitrogen atom of the Meimid ligand in binding to the uranium center is confirmed. Structural analysis at the DFT (B3LYP) level of theory showed a conformational difference of the Meimid ligand in the free gas-phase complex versus the solid state due to small energetic differences and crystal packing effects. Energetic analysis at the MP2 level in the gas phase supported stronger Meimid binding over H2O binding to both UO2(Ac)2 and UO2(NO3)2. In addition, self-consistent reaction field COSMO calculations were used to assess the aqueous phase energetics of combination and displacement reactions involving H2O and Meimid ligands to UO2R2 (R = Ac, NO3). For both UO2(NO3)2 and UO2(Ac)2, the displacement of H2O by Meimid was predicted to be energetically favorable, consistent with experimental results that suggest Meimid may bind uranyl at physiological pH. Also, log(Knitrate/KAc) calculations supported experimental evidence that the binding stoichiometry of the Meimid ligand is dependent upon the nature of the reactant uranyl complex. These results clearly demonstrate that imidazole binds to uranyl and suggest that binding of histidine residues to uranyl could occur under normal biological conditions.

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“…In general, compounds 1 and 2 represent the first examples of uranyl compounds with both nitrate and chromate groups forming, along with the uranyl cations, an extended structure motifs. For uranyl nitrates and uranyl nitrate halides, it is more typical to contain isolated hexagonal or pentagonal uranyl bipyramids sharing with NO 3 triangles one or two of their equatorial edges: [UO 2 (NO 3 ) 2 (H 2 O) 2 ]17 [UO 2 (NO 3 ) 2 (H 2 O) 2 ] · H 2 O,18,19 [UO 2 (NO 3 ) 2 (H 2 O) 2 ] · 4H 2 O,20 [(UO 2 ) 2 (NO 3 ) 2 (H 2 O) 3 (OH) 2 ] · H 2 O,21 and Cs 2 [(UO 2 )(NO 3 )Cl 3 ] 22 . Ur O 6 bipyramids share three of their edges with nitrate triangles in a symmetric fashion in anhydrous alkaline uranyl nitrates A [UO 2 (NO 3 ) 3 ] ( A = Na, K, Rb, Cs) 4–8.…”

Section: Discussionmentioning

confidence: 99%

Highly Kinked Uranyl Chromate Nitrate Layers in the Crystal Structures of A[(UO₂)(CrO₄)(NO₃)] (A = K, Rb)

Siidra

Nazarchuk

Krivovichev

2012

Zeitschrift anorg allge chemie

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Two first uranyl chromate nitrates, K[(UO 2 )(CrO 4 )(NO 3 )] (1) and Rb[(UO 2 )(CrO 4 )(NO 3 )] (2), were prepared by solid-state reactions and characterized by electron microprobe analysis and singlecrystal X-ray diffraction. The compounds are isotypic [1: monoclinic, P2 1 /c, a = 9.881(5), b = 7.215(4), c = 14.226(6) Å, β = 124.85(3)°, V = 832.3(7) Å 3 ; 2: monoclinic, P2 1 /c, a = 9.804(1), b = 7.359(1), c = 14.269(1) Å, β = 122.048(4), V = 872.6(1) Å 3 ]. The structures of 1

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A monoclinic polymorph of uranyl dinitrate trihydrate, [UO₂(NO₃)₂(H₂O)₂]·H₂O

Cited by 13 publications

References 3 publications

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

Interactions of 1-Methylimidazole with UO₂(CH₃CO₂)₂ and UO₂(NO₃)₂: Structural, Spectroscopic, and Theoretical Evidence for Imidazole Binding to the Uranyl Ion

Highly Kinked Uranyl Chromate Nitrate Layers in the Crystal Structures of A[(UO₂)(CrO₄)(NO₃)] (A = K, Rb)

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A monoclinic polymorph of uranyl dinitrate trihydrate, [UO2(NO3)2(H2O)2]·H2O

Cited by 13 publications

References 3 publications

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

Speciation and Structural Study of U(IV) and -(VI) in Perchloric and Nitric Acid Solutions

Interactions of 1-Methylimidazole with UO2(CH3CO2)2 and UO2(NO3)2: Structural, Spectroscopic, and Theoretical Evidence for Imidazole Binding to the Uranyl Ion

Highly Kinked Uranyl Chromate Nitrate Layers in the Crystal Structures of A[(UO2)(CrO4)(NO3)] (A = K, Rb)

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A monoclinic polymorph of uranyl dinitrate trihydrate, [UO₂(NO₃)₂(H₂O)₂]·H₂O

Interactions of 1-Methylimidazole with UO₂(CH₃CO₂)₂ and UO₂(NO₃)₂: Structural, Spectroscopic, and Theoretical Evidence for Imidazole Binding to the Uranyl Ion

Highly Kinked Uranyl Chromate Nitrate Layers in the Crystal Structures of A[(UO₂)(CrO₄)(NO₃)] (A = K, Rb)