Crystal structure of Rb3[UO2(CH3COO)3]2[UO2(CH3COO)(NCS)2(H2O)]

The structure of Rb₃[UO₂(CH₃COO)₃]₂[UO₂(CH₃COO)(NCS)₂(H₂O)] was studied by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system with the unit cell parameters (at 100 K) a = 18.387(3), b = 16.398(3), c = 12.460(2) Å, β = 92.837(5)^°, V = 3752.4(11) ų, space group C2/c, Z = 4, R = 0.0390. The uranium-containing structural units of the crystals are isolated mononuclear groups [UO₂(CH₃COO)₃]^? and [UO₂(CH₃COO)(NCS)₂(H₂O)]^?, belonging to crystal-chemical groups AB ₃ ⁰¹ and AB⁰¹M ₃ ¹ (A = UO ₂ ²⁺ , B⁰¹ = CH₃COO^?, M¹ = NCS^? and H₂O) of uranyl complexes, respectively. The uranium-containing complexes are linked in a framework by hydrogen bonds and by electrostatic interactions with Rb⁺ cations.     

Synthesis and structure of (NH<Subscript>4</Subscript>)<Subscript>3</Subscript>[UO<Subscript>2</Subscript>(CH<Subscript>3</Subscript>COO)<Subscript>3</Subscript>]<Subscript>2</Subscript>(NCS)

The compound (NH₄)₃[UO₂(CH₃COO)₃]₂(NCS) (I) was synthesized and examined by single crystal X-ray diffraction analysis. The compound crystallizes in the rhombic system with the unit cell parameters a = 11.5546(4), b = 18.5548(7), c = 6.7222(3) Å, V = 1441.19(10) ų, space group P2₁2₁2, Z = 2, R = 0.0345. The uranium-containing structural units of crystals of I are isolated mononuclear groups [UO₂(CH₃COO)₃]^? belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = CH₃COO^?) of uranyl complexes. The specific features of packing of the uranium-containing complexes in the crystal structure are considered.     

A single crystal X-ray diffraction and IR study of (NH4)2[(UO2)C2O4(CH3COO)2]

A single crystal X-ray diffraction study of (NH₄)₂[(UO₂)C₂O₄(CH₃COO)₂] was performed. The compound crystallizes in the monoclinic system; unit cell parameters (at 100 ± 2 K): a = 6.793(2), b = 18.866(6), c = 20.730(7) Å, β = 90.040(7)°, space group P2₁/c, Z = 8, V = 2656.5(14) ų, R = 0.0495. The main structural units of the crystals are mononuclear complexes [(UO₂)C₂O₄(CH₃COO)₂]^2? belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = CH₃COO^? and C₂O ₄ ^2? ) of uranyl complexes. The uranium-containing anions are linked with ammonium cations by electrostatic interactions and a system of hydrogen bonds. The results of the X-ray diffraction analysis of the compound are well consistent with the IR data.     

Synthesis and structure of Cs3[UO2(CH3COO)3]2(NCS)·H2O

The compound Cs₃[UO₂(CH₃COO)₃]₂(NCS)·H₂O (I) was synthesized and studied by IR spectroscopy and single crystal X-ray diffraction. Compound I crystallizes in the monoclinic system with the following unit cell parameters: a = 7.8286(9), b = 19.892(2), c = 20.050(2) Å, β = 94.527(2)°, space group P2₁/c, Z = 4, R = 0.0387. The uranium-containing structural units in crystals of I are mononuclear complexes [UO₂(CH₃COO)₃]^? belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = CH₃COO^?) of uranyl complexes.     

A single crystal X-ray diffraction study of R[UO2(C2H5COO)3] (R = K or NH4)

A single crystal X-ray diffraction study of R[UO₂(C₂H₅COO)₃] [R = K (I) or NH₄ (II)] was performed. Both compounds crystallize in the cubic system, unit cell parameters for I: a = 11.4329(3) Å (at 100 K), space group P2₁3, Z = 4; for II: a = 11.60503(7) Å (at 123 K), space group P2₁3, Z = 4. The structures of crystals of I and II contain complex anions [UO₂(C₂H₅COO)₃]^? belonging to crystal-chemical group AB ₃ ⁰¹ of uranyl complexes (A = UO ₂ ²⁺ , B⁰¹ = C₂H₅COO^?). These anions are linked in a framework by electrostatic interactions with outer-sphere cations R and by hydrogen bonds (in case of II). The effect of the kind of carboxylate ion on structural features of R[UO₂L₃] (L is propionate or acetate ion) is discussed.     

Synthesis and structural study of new potassium uranyl selenates K2(H5O2)(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)4 and K3(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)5

Single crystals of new uranyl selenates K₂(H₅O₂)(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₄ (1) and K₃(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₅ (2) were prepared by isothermal evaporation at room temperature. The crystal structure of 1 was solved by the direct method [C2/c, a = 17.879(5), b = 8.152(5), c = 17.872(5) Å, β = 96.943(5)°, V = 2585.7(19) ų, Z = 4] and refined to R ₁ = 0.0449 (wR ₂ = 0.0952) for 2600 reflections with |F _o| ≥ 4σ _F . The structure of 2 was solved by the direct method [P2₁/c, a = 17.8377(5), b = 8.1478(5), c = 23.696(1) Å, β = 131.622(2)°, V = 2574.5(2) ų, Z = 4] and refined to R ₁ = 0.0516 (wR ₂ = 0.1233) for 4075 reflections with |F _o| ≥ 4σ _F . The structures of 1 and 2 are based on [(UO₂)₂(SeO₄)₄(H₂O)₂]^4? layers. The charge of the inorganic layer is compensated by potassium and oxonium ions arranged in the interlayer space. Each K ion is surrounded by seven O atoms belonging to uranyl selenate layers and water molecules, so that it binds with each other the adjacent uranyl selenate structural elements.     

A single crystal X-ray diffraction study of Na4(UO2)4(i-C4H9COO)11(NO3)·3H2O

Synthesis and the results of IR and single crystal X-ray diffraction study of Na₄(UO₂)₄(i-C₄H₉COO)₁₁·(NO₃)·3H₂O are reported. The crystals are monoclinic; the unit cell parameters at 100 K are as follows: a = 13.697(2), b = 20.285(3), c = 15.991(3) Å, β = 103.760(3)°, space group P2₁, Z = 2, R = 0.0650. The uraniumcontaining structural units are mononuclear moieties [UO₂(i-C₄H₉COO)₃]^? and [UO₂(NO₃)(i-C₄H₉COO)₂]^?, belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = i-C₄H₉COO^? and NO ₃ ^? ) of uranyl complexes. The IR data are consistent with the results of the single crystal X-ray diffraction study. The influence of the carboxylate ligand volume on the structure of Na[UO₂L₃]·nH₂O crystals (L = acetate, n-butyrate, isovalerate ion) is analyzed.     

Synthesis and crystal structure of a new uranyl selenite(IV)-selenate(VI), [C5H14N]4[(UO2)3(SeO4)4(HSeO3)(H2O)](H2SeO3)(HSeO4)

Crystals of a new uranyl selenite(IV)-selenate(VI), [C₅H₁₄N]₄[(UO₂)₃(SeO₄)₄(HSeO₃)(H₂O)]·(H₂SeO₃)(HSeO₄) were obtained by evaporation from aqueous solutions. The compound crystallizes in the triclinic system, space group $P\bar 1$ , a = 11.7068(9), b = 14.8165(12), c = 16.9766(15) Å, α = 73.899(6)°, β = 76.221(7)°, γ = 89.361(6)°, V = 2743.0(4) ų, Z = 2. The crystal structure was solved by direct methods and refined to R ₁ = 0.081 (wR ₂ = 0.150) for 6966 reflections with |F _hkl | ≥ 4σ(|F _hkl |). The structure is based on [(UO₂)₃(SeO₄)₄(HSeO₃)(H₂O)]^3? layers formed by joining uranyl pentagonal bipyramids, selenate tetrahedra, and selenite pyramids. The [HSe(VI)O₄]^? anions, [H₂Se(IV)O₃] molecules, and protonated methylbutylamine cations are arranged between the layers.     

Synthesis and crystal structure of a uranyl bichromate, [CH6N3]2[(UO2)(CrO4)(Cr2O7)](H2O)

Crystals of the first uranyl bichromate, [CH₆N₃]₂[(UO₂)(CrO₄)(Cr₂O₇)](H₂O), were obtained by evaporation from aqueous solutions. The compound crystallizes in the triclinic system, space group $P\bar 1$ , a = 7.1829(17), b = 9.304(3), c = 14.884(4) Å, α = 102.43(2)°, β = 97.98(2)°, γ = 101.07(2)°, V = 936.3(5) ų, Z = 2. The structure was solved by direct methods and refined by the full-matrix least-squares method to R ₁ = 0.064 (wR ₂ = 0.138) for 2225 reflections with |F _hkl | ≥ 4σ(|F _hkl |). The structure is based on infinite [(UO₂)(CrO₄)(Cr₂O₇)]^2? chains where [UO₇]^8? pentagonal bipyramids are linked by tridentate [Cr(1)O₄]^2? groups and [Cr₂O₇]^2? groups; these chains run along x axis and are oriented parallel to $(0\bar 11)$ . Trigonal [CH₆N₃]⁺ cations and water molecules are arranged between the chains.     

Partially ordered organic-inorganic nanocomposites in the system UO<Subscript>2</Subscript>SeO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O-NH<Subscript>3</Subscript>(CH<Subscript>2</Subscript>)<Subscript>9</Subscript>NH<Subscript>3</Subscript>

The compound [NH₃(CH₂)₉NH₃]₂[(UO₂)₃(SeO₄)₅(H₂O)₂](H₂O)_x (1) was prepared by isothermal evaporation from aqueous uranyl selenate solutions containing 1,9-diaminononane. A structural study showed that the compound is a partially ordered organic-inorganic nanocomposite. The structural model of the inorganic complex was determined by single crystal X-ray diffraction a = 19.5572(5), c = 47.878(2) Å, V= 15859.1(9) ų, Z= 12; R₁ = 0.1318, wR₂ = 0.3186 for 2808 reflections with |F_o| ≥ 4σ_F). The structure consists of double hydrogen-bonded [(UO₂)₃(SeO₄)₅(H₂O)₂]^2- layers parallel to the (001) plane. The disordered protonated 1,9-diaminononane molecules and water molecules are arranged between the layers. The inorganic layered complex [(UO₂)₃(SeO₄)₅(H₂O)₂]^2- belongs to a new type that was not observed previously in the structures of inorganic and organometallic compounds.     

Geometric isomerism of layered complexes of uranyl selenates: Synthesis and structure of (H3O)[C5H14N]2[(UO2)3(SeO4)4(HSeO4)(H2O)] and (H3O)[C5H14N]2[(UO2)3(SeO4)4(HSeO4)(H2O)](H2O)

New uranyl selenates with organic cations (H₃O)[C₅H₁₄N]₂[(UO₂)₃(SeO₄)₄(HSeO₄)(H₂O)] (I) and (H₃O)[C₅H₁₄N]₂[(UO₂)₃(SeO₄)₄(HSeO₄)(H₂O)](H₂O) (II) were synthesized by evaporation of aqueous solutions and studied. Compound I has monoclinic symmetry, space group C2/c, a = 16.7572(13), b = 11.7239(12), c = 19.0490(13) Å, β = 98.875(6)°, V = 3697.6(5) ų, Z = 4. The crystal structure was solved by the direct method and refined to R ₁ = 0.085 for 2868 reflections with |F _hkl | ≥ 4σ|F _hkl |. Compound II has monoclinic symmetry, space group P2₁/n, a = 10.8252(10), b = 19.0007(10), c = 18.6463(15) Å, β = 100.324(7)°, V = 3773.2(5) ų, Z = 4. The crystal structure was solved by the direct method and refined to R ₁ = 0.084 for 5721 reflections with |F _hkl | ≥ 4σ|F _khl |. The structures of I and II are based on layered complexes [(UO₂)₃(SeO₄)₄(HSeO₄)(H₂O)]^3? formed by combination of uranyl pentagonal bipyramids and selenate tetrahedra. H₃O⁺ cations, water molecules, and protonated methylbutylamine cations are located in the interlayer space. Geometric isomerism of two-dimensional complexes [(UO₂)₃(SeO₄)₅(H₂O)] in the structures of uranyl selenates was found and described.     

Crystal structure of [CH<Subscript>3</Subscript>NH<Subscript>3</Subscript>][(UO<Subscript>2</Subscript>)(H<Subscript>2</Subscript>AsO<Subscript>4</Subscript>)<Subscript>3</Subscript>]

The crystal structure of a previously unknown compound [CH₃NH₃][(UO₂)(H₂AsO₄)₃] was solved by direct methods and refined to R ₁ = 0.038 for 3041 reflections with |F _hkl | >-4σ |F _hkl |. The compound crystallizes in the monoclinic system, space group P2₁/c, a = 8.980(1), b = 21.767(2), c = 7.867(1) Å, β = 115.919(5)°, V = 1383.1(3) ų, Z = 4. In the structure of the compound, pentagonal bipyramids of uranyl ions, sharing bridging atoms with tetrahedral [H₂AsO₄]^? anions, form strongly corrugated layered complexes [(UO₂)(H₂AsO₄)₃]^? arranged parallel to the (100) plane. The protonated methylamine molecules [CH₃NH₃]⁺ form unidimensional tapelike packings parallel to the c axis and linked by hydrophilic-hydro-phobic interactions. The topology of the layered uranyl arsenate complex [(UO₂)(H₂AsO₄)₃]^? is unusual for uranyl compounds and was not observed previously. A specific feature of this topology is the presence of monodentate arsenate “branches” arranged within the layer.     

Crystal Structure of U(VI) Peroxo Complex with Triphenylphosphine Oxide {(UO2)2O2[OP(C6H5)3]6}(ClO4)2

The peroxo complex {(UO₂)₂O₂[OP(C₆H₅)₃]₆}(ClO₄)₂ was synthesized, and its crystal structure was determined [triclinic unit cell: a = 10.523(2), b = 16.242(3), c = 16.978(3) Å, = 65.79(3)°, = 85.06(3)°, = 77.14(3)°, space group P-1, Z = 1, V = 2580.1(9) ų, d _{c a l c} = 2.789 g cm^{- 3}; CAD4, MoK , graphite monochromator, direct method, R ₁ = 0.0368 for 3115 observed reflections, wR ₂ = 0.1107 for 4403 unique reflections, 622 refined parameters]. {(UO₂)₂O₂[OP(C₆H₅)₃]₆}(ClO₄)₂ has monomeric structure and consists of the complex cations {(UO₂)₂O₂[OP(C₆H₅)₃]₆}^{2 +} and ClO₄ ^- anions. The uranium atom has a pentagonal-bipyramidal oxygen surrounding (CN 7). Uranyl groups UO₂ ^{2 +} are linear and symmetrical, the U = O bond lengths are 1.780(8) and 1.787(8) Å, the O(1) = U = O(2) bond angles are 178.7(4) Å. The equatorial planes of bipyramids are formed by oxygen atoms of three TPPO molecules [U-O_{T P P O} 2.352(8)-2.368(7) Å, average 2.362 Å] and peroxo group O₂ ^{2 -} [U-O_{p e r} 2.285(8) and 2.323(8) Å, average 2.305 Å]. Two pentagonal bipyramids sharing the common edge O(3)-O(3)^(a) form the centrosymmetrical peroxo-bridged diuranyl complex {(UO₂)₂O₂[OP(C₆H₅)₃]₆}^{2 +} with the [UO₂O₂UO₂]^{2 +} core. The length of the O(3)-O(3)^{( 9a )} edge is 1.426(15) Å.     

Crystal Structure of (H3O)6[(UO2)5(SeO4)8(H2O)5](H2O)5

Crystals of (H₃O)₆[(UO₂)₅(SeO₄)₈(H₂O)₅](H₂O)₅ were prepared from aqueous solutions by evaporation. The crystal structure [monoclinic system, space group P2₁/m, a = 13.835(2), b = 13.4374(16), c = 14.310(3) Å, β = 108.004(14)°, V = 2530.1(7) Å ³] was solved by the direct method and refined to R ₁ = 0.090 for 4409 reflections with |F _hkl ≥ 4σ|F _hkl |. The structure is based on [(UO₂)₅(SeO₄)₈(H₂O)₅]⁶⁻ layers arranged parallel to the (101) plane; these layers have a unique topological structure. The U(1)O₆(H₂O) and U(3)O₆(H₂O) linked through selenate groups form chains running along [ [`1]\bar 1 01] direction. The chains are combined in layers by U(2)O₆(H₂O) bipyramids. The layers are linked with each other by hydrogen bonds through the H₂O and H₃O⁺ groups located between the layers.     

Phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2]

The phase diagrams of the ternary liquid systems [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂] and [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] and of the quaternary liquid system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂]-[Th(NO₃)₄(TBP)₂] at T = 298.15 K are constructed. The phase diagrams are characterized by areas of homogeneous solutions and of two-phase liquid systems (systems with phase separation), with one phase (I) enriched in [Ce(NO₃)₃(TBP)₃], [Th(NO₃)₄(TBP)₂], and [UO₂(NO₃)₂(TBP)₂], and the other phase (II), in C₁₀H₂₂. Using the data on the mutual solubility of the components in the systems under consideration and equations of the NRTL model, the parameters of intermolecular interactions and the excess Gibbs energies (G ^ex) were calculated for the binary, ternary, and quaternary systems. Passing from the ternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] to the quaternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂ (TBP)₂]-[Th(NO₃)₄(TBP)₂] does not appreciably affect the distribution of C₁₀H₂₂ between phases I and II, but leads to the redistribution of [Ce(NO₃)₃(TBP)₃] into phase II and of [Th(NO₃)₄(TBP)₂] into phase I.     

Crystal Structure of K[UO2(NO3)3] and Some Features of Compounds M[UO2(NO3)3] (M = K,Rb, and Cs)

Greenish-yellow transparent crystals of K[UO₂(NO₃)₃] were prepared from aqueous solutions as by-product in synthesis of potassium chromatouranylates. The crystal structure was solved by the direct methods and refined to R ₁ = 0.037 (wR ₂ = 0.070) for 1452 reflections with |F _hkl| 4|F _hkl|. Mono- clinic system, space group C2/c, a = 13.4877(10), b = 9.5843(7), c = 7.9564(6) Å, = 116.124(2)°, V = 923.45(12) ų. The structure of K[UO₂(NO₃)₃] contains isolated complex ions [UO₂(NO₃)₃]^- whose uranyl groups are aligned parallel to the [-101] plane. The K⁺ cations, coordinated by twelve oxygen atoms, are located between the complex anions. Comparison of the structure with known data on M[UO₂(NO₃)₃] compounds (M = K, Rb, Cs) suggests the possibility of phase transitions due to relatively small displacements of [UO₂(NO₃)₃]^- anions and K⁺ cations, retaining the general structural motif.     

Crystal Structure of (H3O)2[(UO2)2(SeO4)3(H2O)2](H2O)3.5

Crystals of (H₃O)₂[(UO₂)₂(SeO₄)₃(H₂O)₂](H₂O)_3.5 were prepared from aqueous solutions by evaporation. The crystal structure [monoclinic system, space group P2₁/m, a = 11.9402(11), b = 13.6452(14), c = 13.7271(12) Å, β = 109.436(7)°, V = 2109.1(3) ų] was solved by the direct method and refined to R ₁ = 0. 048 (wR ₂ = 0. 082) for 3677 reflections with |F _hkl |F _hkl |. The structure consists of [(UO₂)₂(SeO₄)₃(H₂O)₂]₂₋ layers arranged parallel to the (010) plane. The layers are formed by uranium and selenium coordination polyhedra sharing common vertices and are linked with each other by hydrogen bonds through the H₂O and H₃O⁺ groups arranged between the layers. __________ Translated from Radiokhimiya, Vol. 47, No. 5, 2005, pp. 412–414. Original Russian Text Copyright ? 2005 by Krivovichev, Kahlenberg.     

An X-ray diffraction study of Rb[UO2(SeO4)F]·H2O

An X-ray diffraction study of Rb[UO₂(SeO₄)F]·H₂O (I) was performed. The compound crystallizes in the rhombic system with the following unit cell parameters: a = 8.4753(6), b = 13.5234(9), c = 13.5296(9) Å, space group Pnma, Z = 8, V = 1550.7(2) ų; R = 0.0248. The principal structural units of crystals of I are [UO₂(SeO₄)F]^? layers belonging to crystal-chemical group AT³M² (A = UO ₂ ²⁺ , T³ = SeO ₄ ^2? , M² = F^?) of uranyl complexes. The uranium-containing layered units are combined via electrostatic interaction with Rb cations and via a system of hydrogen bonds involving outer-sphere water molecules.     

Complexation of actinides(VI) with furan-2-carboxylic and thiophene-2-carboxylic acids in aqueous solutions and synthesis of crystalline compounds

Crystalline uranyl compounds with furan-2-carboxylic (F2C) and thiophene-2-carboxylic (T2C) acids containing the complex anions [UO₂(OOCC₄H₃O)₃]^? and [UO₂(OOCC₄H₃S)₃]^? were synthesized and studied by single crystal X-ray diffraction. A previously unknown compound of a transuranium element, Pu(VI), with T2C, also containing the complex anions [PuO₂(OOCC₄H₃S)₃]^?, was synthesized. With Pu(VI) taken as example, the complexation of hexavalent actinides with F2C and T2C in aqueous solutions was studied, and the stability of the complexes PuO₂L⁺ (L is F2C or T2C anion) was determined. The Pu(VI) complexes with F2C are slightly more stable than those with T2C but less stable than Pu(VI) monoacetate complexes. The spectral characteristics of the complexes are discussed.     

Synthesis and single crystal X-ray diffraction study of U(VI), Np(VI), and Pu(VI) perchlorate hydrates

The compounds [AnO₂(H₂O)₅](ClO₄)₂ (An = Np, Pu) and [NpO₂(ClO₄)₂(H₂O)₃] were prepared as single crystals, which were studied by X-ray diffraction at 100 K. The structural type at room temperature was determined. The low-temperature modification of [UO₂(H₂O)₅](ClO₄)₂ was found and structurally studied. The coordination polyhedra in [AnO₂(H₂O)₅]²⁺ are weakly distorted pentagonal bipyramids with averaged interatomic distances An-O of 1.754, 1.744, and 1.732 Å in the “yl” groups and of 2.415, 2.416, and 2.409 Å in the equatorial planes for U, Np, and Pu, respectively. Hence, in the complex cations [AnO₂(H₂O)₅]²⁺ the actinide contraction is manifested only in regular shortening of the An-O interatomic distances in the “yl” groups. The compound [NpO₂(ClO₄)₂(H₂O)₃], isostructural to its known uranyl analog, appeared to be the first, proved by single crystal X-ray diffraction, example of a compound with coordination interaction between the perchlorate ion and the neptunyl(VI) cation.