Syntheses, structures, and ion-exchange properties of the three-dimensional framework uranyl gallium phosphates, Cs4[(UO2)2(GaOH)2(PO4)4].H2O and Cs[UO2Ga(PO4)2

The reaction of UO(2)(NO(3))(2).6H(2)O with Cs(2)CO(3) or CsCl, H(3)PO(4), and Ga(2)O(3) under mild hydrothermal conditions results in the formation of Cs(4)[(UO(2))(2)(GaOH)(2)(PO(4))(4)].H(2)O (UGaP-1) or Cs[UO(2)Ga(PO(4))(2)] (UGaP-2). The structure of UGaP-1 was solved from a twinned crystal revealing a three-dimensional framework structure consisting of one-dimensional (1)(infinity)[Ga(OH)(PO(4))(2)](4-) chains composed of corner-sharing GaO(6) octahedra and bridging PO(4) tetrahedra that extend along the c axis. The phosphate anions bind the UO(2)(2+) cations to form UO(7) pentagonal bipyramids. The UO(7) moieties edge-share to create dimers that link the gallium phosphate substructure into a three-dimensional (3)(infinity)[(UO(2))(2)(GaOH)(2)(PO(4))(4)](4-) anionic lattice that has intersecting channels running down the b and c axes. Cs(+) cations and water molecules occupy these channels. The structure of UGaP-2 is also three-dimensional and contains one-dimensional (1)(infinity)[Ga(PO(4))(2)](3-) gallium phosphate chains that extend down the a axis. These chains are formed from fused eight-membered rings of corner-sharing GaO(4) and PO(4) tetrahedra. The chains are in turn linked together into a three-dimensional (3)(infinity)[UO(2)Ga(PO(4))(2)](1-) framework by edge-sharing UO(7) dimers as occurs in UGaP-1. There are channels that run down the a and b axes through the framework. These channels contain the Cs(+) cations. Ion-exchange studies indicate that the Cs(+) cations in UGaP-1 and UGaP-2 can be exchanged for Ca(2+) and Ba(2+). Crystallographic data: UGaP-1, monoclinic, space group P2(1)/c, a = 18.872(1), b = 9.5105(7), c = 14.007(1) A, beta = 109.65(3)(o) , Z = 4 (T = 295 K); UGaP-2, triclinic, space group P, a = 7.7765(6), b = 8.5043(7), c = 8.9115(7) A, alpha = 66.642(1)(o), beta = 70.563(1)(o), gamma = 84.003(2)(o), Z = 2 (T = 193 K).     

A novel open framework uranyl molybdate: synthesis and structure of (NH4)4[(UO2)5(MoO4)7](H2O)5

Single crystals of (NH(4))(4)[(UO(2))(5)(MoO(4))(7)](H(2)O)(5) have been synthesized hydrothermally using (NH(4))(6)Mo(7)O(24), (UO(2))(CH(3)COO)(2).2H(2)O, and H(2)O at 180 degrees C. The phase has been characterized by single-crystal X-ray diffraction using a merohedrally twinned single crystal: it is hexagonal, P6(1), a = 11.4067(5) A, c = 70.659(5) A, V = 7961.9(7) A(3), and Z = 6. The structure is based upon an open framework with composition [(UO(2))(5)(MoO(4))(7)](4-) that is composed of UO(7) pentagonal bipyramids that share vertexes with MoO(4) tetrahedra. The framework has large channels (effective pore size: 4.8 x 4.8 A(2)) parallel to the c axis and a system of smaller channels (effective pore size: 2.5 x 3.6 A(2)) parallel to [100], [110], [010], [110], [110], and [110]. The channels are occupied by NH(4)(+) cations and H(2)O molecules. The topological structure of the uranyl molybdate framework can be described either in terms of fundamental chains of UO(7) pentagonal bipyramids and MoO(4) tetrahedra or in terms of tubular building units parallel to the c axis.     

硫氰酸铀铣(18-冠-6)铵(或钾)配合物的合成, 特性和结构

本文报导了硫氰酸铀铣(18-冠-6)铵和硫氰酸铀酰(18-冠-6)钾两种固体配合物的合成。由测定其物理常数及谱学数据, 确定了配合物的组成为[(C12H24O6)M]2UO2(NCS)4H2O(M=NH4, K)。X射线结构分析确定了二种单晶的结构。铵配合物属正交晶素, 空间群为Fdd2, 钾配合物属单斜晶系, 空间群为C2/c。     

An unprecedented uranyl phosphate framework in the structure of [(UO2)3(PO4)O(OH)(H2O)2](H2O)

The new uranyl phosphate [(UO2)3(PO4)O(OH)(H2O)2](H2O) (1) with an unprecedented framework structure has been synthesized at 150 and 185 degrees C. The structure (tetragonal, P4(2)/mbc, a = 14.015(1) A, c = 13.083(2) A, V = 2575.6(4) A(3), Z = 8) contains uranyl phosphate chains composed of uranyl pentagonal and hexagonal bipyramids and phosphate tetrahedra linked by sharing of polyhedral edges. The uranyl phosphate chains are aligned both along [100] and [010] and are linked into a novel framework structure involving channels along [001]. Topologically identical chains occur linked into sheets in more than a dozen uranyl phosphate minerals, but these chains have never been observed in opposing orientations and linked into a framework as in 1.     

First Mixed Alkaline Uranyl Molybdates: Synthesis and Crystal Structures of CsNa3[(UO2)4O4(Mo2O8)] and Cs2Na8[(UO2)8O8(Mo5O20)]

Two new mixed alkaline uranyl molybdates CsNa₃[(UO₂)₄O₄Mo₂O₈] ( 1 ) and Cs₂Na₈[(UO₂)₈O₈(Mo₅O₂₀)] ( 2 ) have been obtained by high‐temperature solid state reactions. Their crystal structures have been solved by direct methods: Compound 1 : triclinic, P , a = 6.46(1), b = 6.90(1), c = 11.381(2) Å, α = 84.3(1), β = 91.91(1), γ = 80.23(1)°, V = 488.6(2) ų, R₁ = 0.06 for 2865 unique reflections with |F_o| ≥ 4σ_F; Compound 2 : orthorhombic, Ibam, a = 6.8460(2), b = 23.3855(7), c = 12.3373(3) Å, V = 1975.2(1) ų, R₁ = 0.049 for 2120 unique reflections with |F_o| ≥ 4σ_F. The structure of 1 contains complex sheets of UrO₅ pentagonal bipyramids and molybdenum polyhedra. The sheets have [(UO₂)₂O₂(MoO₅)] composition. Natrium and cesium atoms are located in the interlayer space. Cesium atoms are situated between the molybdenum clusters, whereas natrium atoms are segregated between the uranyl complexes. The large Cs⁺ ions are localized between the Mo₂O₉ groups and force the molybdenum polyhedra to rotate relative to the [(UO₂)₂O₂(MoO₅)] sheets. Such rotation is impossible for U⁶⁺ polyhedra due to their rigid edge‐sharing complexes. The distance between the U⁶⁺ polyhedra vertices of neighboring layers is 3.8 Å, that allows the Na⁺ ion to be positioned between the uranyl groups. The crystal structure of 2 is based upon a framework consisting of [(UO₂)₂O₂(MoO₅)] sheets parallel to (010). The sheets are linked into a 3‐D framework by sharing vertices with the Mo(2)O₄ tetrahedra, located between the sheets. Each MoO₄ tetrahedron shares two of its corners with two MoO₆ octahedra in the sheet above, and the other two with MoO₆ octahedra of the sheet below. Thus four MoO₆ octahedra and one MoO₄ tetrahedron form chains of composition Mo₅O₁₈. The resulting framework has a system of channels occupied by the Cs⁺ and Na⁺ ions.     

A uranyl sulfate cluster in Na10[(UO2)(SO4)4](SO4)2·3H2O

Decasodium uranyl hexa­sulfate trihydrate, Na₁₀[(UO₂)(SO₄)₄](SO₄)₂·3H₂O, contains an unusual uranyl sulfate cluster with the composition [(UO₂)(SO₄)₄]^6?. The cluster is composed of a uranyl pentagonal bipyramid and four sulfate tetrahedra. Three sulfate tetrahedra are linked to the uranyl pentagonal bipyramid by the sharing of vertices, and the other shares an equatorial edge of the uranyl pentagonal bipyramid. The uranyl sulfate clusters occur in layers parallel to (010). The structure also contains two isolated symmetrically distinct sulfate tetrahedra, which also occur in layers parallel to (010). The uranyl sulfate clusters and isolated sulfate tetrahedra are linked through bonds to Na⁺ cations, and by hydrogen bonding involving the water molecules.     

A study on the thermal stability of uranyl phosphates (UO2)3(PO4)2, (UO2)2P2O7, and UO2(PO3)2 using a static non-isothermal method

A static, non iso-thermal method is used to investigate the stability of uranyl phosphates. The resulting oxygen partial pressures can be expressed as: (UO₂)₃(PO₄)₂, (1089–1280°K) log pO₂/atm = (−18480±400)/T+(13.11±0.33)(UO₂)₂P₂O₇, (979–1130°K) log pO₂/atm = (−27460±540)/T+(24.26±0.51)UO₂(PO₃)₂, (963–1118°K) log pO₂/atm = (−25320±680)/T+(22.58±0.66).Using these results, a part of the phase diagram UO_x (x = 2 to 3) − P₂O₅ is calculated.     

Crystal structure of (C2H7N4O)2[(UO2)2)(OH)2(C2O4)(CHO2)2]

An X-ray diffraction study of the single crystals of (C₂H₇N₄O)₂[(UO₂)₂(OH)₂(C₂O₄)(CHO₂)₂] was carried out. The compound crystallizes in the triclinic system, space group $P\bar 1$ , Z = 2, a = 5.5621(8) Å, b = 8.1489(10) Å, c = 11.8757(16) Å, α = 88.866(7)°, β = 82.204(6)°, γ = 87.378(6)°, V = 532.7(1) ų, ρ_calcd = 2.988 g/cm³. The main structural units in the crystal are the [(UO₂)₂(OH)₂(C₂O₄)(CHO₂)₂)]^2? chains corresponding to the crystal chemical group A₂M ₂ ² K⁰²M ₂ ¹ (A = UO ₂ ²⁺ , M² = OH^?, K⁰² = C₂O ₄ ^2? , M¹ = CHO ₂ ^? ) of uranyl complexes. The chains are united into a three-dimensional framework through the electrostatic interaction and hydrogen bonds involving uranyl, oxalate, and hydroxyl groups, formate ions, and 1-carbamoylguanidinium cations.     

Structural Diversity of Sheets in Rubidium Uranyl Oxoselenates: Synthesis and Crystal Structures of Rb2[(UO2)(SeO4)2(H2O)](H2O), Rb2[(UO2)2(SeO4)3(H2O)2](H2O)4, and Rb4[(UO2)3(SeO4)5(H2O)]

Single crystals of three rubidium uranyl selenates, Rb₂[(UO₂)(SeO₄)₂(H₂O)](H₂O) ( 1 ), Rb₂[(UO₂)₂(SeO₄)₃(H₂O)₂](H₂O)₄ ( 2 ), and Rb₄[(UO₂)₃(SeO₄)₅(H₂O)] ( 3 ), have been prepared by evaporation from aqueous solutions made out of mixtures of uranyl nitrate, selenic acid and Rb₂CO₃. The structures of all compounds have been solved by direct methods on the basis of X‐ray diffraction data sets. The crystallographic data are as follows: ( 1 ): orthorhombic, Pna2₁, a = 13.677(2), b = 11.8707(13), c = 7.6397(9) Å, V = 1240.4(3) ų, R₁ = 0.045 for 2396 independent observed reflections; ( 2 ): triclinic, P1¯, a = 8.4261(12), b = 11.8636(15), c = 13.3279(18) Å, α = 102.612(10), β = 107.250(10), γ = 102.510(10)°, V = 1183.7(3) ų, R₁ = 0.067 for 4762 independent observed reflections; ( 3 ): orthorhombic, Pbnm, a = 11.3761(14), b = 15.069(2), c = 19.2089(17) Å, V = 3292.9(7) ų, R₁ = 0.075 for 3808 independent observed reflections. The structures of the phases 1 , 2 , and 3 are based upon uranyl selenate hydrate sheets composed from corner‐sharing pentagonal [UO₇]^8— bipyramids and [SeO₄]^2— tetrahedra. In the crystal structure of 1 , the sheets have composition [(UO₂)(SeO₄)₂(H₂O)]^2— and run parallel to (001). The interlayer contains Rb⁺ cations and additional H₂O molecules. In structure of 2 , the [(UO₂)₂(SeO₄)₃(H₂O)₂]^2— sheets are oriented parallel to (101). Highly disordered Rb⁺ cations and H₂O molecules are located between the sheets. The structure of 3 is based upon [(UO₂)₃(SeO₄)₅(H₂O)]^4— sheets stacked parallel to (010) and contains Rb⁺ cations in the interlayers. The topologies of the uranyl oxoselenate sheets observed in the structures of 1 , 2 , and 3 are related to the same simple and highly‐symmetric graph consisting of 3‐connected white and 6‐connected black vertices.     

Synthesis of the stable UO2I2, the last of the uranyl dihalides. X-ray crystal structure of [UO2I2(py)3

Treatment of UO2(OTf)2 with pure Me3SiI led to the quantitative formation of UO2I2 (1). This compound dissolved in pyridine and thf to give the red adducts [UO2I2L3][L = py (2) or thf (3)], which were also obtained from the metathetical reaction of UO2(OTf)2 and KI. The crystal structure of has been determined. The uranyl diiodide complexes - are thermally quite stable, providing that strictly anhydrous conditions are employed.     

Raman spectroscopic study of the uranyl minerals vanmeersscheite U(OH)4[(UO2)3(PO4)2(OH)2].4H2O and arsenouranylite Ca(UO2)[(UO2)3(AsO4)2(OH)2].(OH)2.6H2O

Raman and infrared spectra of secondary uranyl phosphate vanmeersscheite and Raman spectrum of secondary uranyl arsenate arsenuranylite were recorded and interpreted, and the spectra related to the structure of the minerals. Observed bands were attributed to the stretching and bending vibrations of uranyl, phosphate and/or arsenate units and OH (H(2)O and OH(-)) units. Phosphuranylite sheet topology is characteristic for both minerals. U-O bond lengths in uranyl were calculated from the spectra and compared with those inferred for vanmeersscheite from the X-ray single crystal structure analysis. O-H...O hydrogen bonds in both minerals were also inferred using the Libowitzky empirical relation.