Low‐Dimensional Structural Units in Amine‐Templated Uranyl Oxoselenates(VI): Synthesis and Crystal Structures of [C3H12N2][(UO2)(SeO4)2(H2O)2](H2O), [C5H16N2]2[(UO2)(SeO4)2(H2O)](NO3)2, [C4H12N][(UO2)(SeO4)(NO3)], and [C4H14N2][(UO2)(SeO4)2(H2O)]

The crystals of four amine‐templated uranyl oxoselenates(VI), [C₃H₁₂N₂][(UO₂)(SeO₄)₂(H₂O)₂](H₂O) ( 1 ), [C₅H₁₆N₂]₂[(UO₂)(SeO₄)₂(H₂O)](NO₃)₂ ( 2 ), [C₄H₁₂N][(UO₂)(SeO₄)(NO₃)] ( 3 ), and [C₄H₁₄N₂][(UO₂)(SeO₄)₂(H₂O)] ( 4 ) were prepared by evaporation from aqueous solution of uranyl nitrate, selenic acid and the respective amine. The crystal structures of all four compounds have been solved by direct methods from X‐ray diffraction data. The structure of 1 (triclinic, , a = 7.5611(16), b = 7.7650(17), c = 12.925(3) Å, α = 94.605(18), β = 94.405(17), γ = 96.470(17)°, V = 748.8(3) ų, R₁ = 0.029 for 2769 unique observed reflections) is based upon 0D‐units of the composition [(UO₂)₂(SeO₄)₄(H₂O)₄]^4?. These discrete units are composed from two pentagonal [UO₇]^8? bipyramids linked via [SeO₄]^2? tetrahedra and are unknown in structural chemistry of uranium so far. The structure of 2 (monoclinic, C2/c, a = 28.916(5), b = 8.0836(10), c = 11.9856(16) Å, β = 110.909(11)°, V = 2617.1(6) ų, R₁ = 0.035 for 2578 unique observed reflections) contains [(UO₂)(SeO₄)₂(H₂O)]^2? chains of corner‐sharing pentagonal [UO₇]^8? bipyramids and [SeO₄]^2? tetrahedra. The chains run parallel to the c axis and are arranged into layers parallel to (100). In the structure of 3 (monoclinic, C2/m, a = 21.244(5), b = 7.1092(11), c = 8.6581(18) Å, β = 97.693(17)°, V = 1295.8(4) ų, R₁ = 0.027 for 1386 unique observed reflections), pentagonal [UO₇]^8? bipyramids share corners with three [SeO₄]^2? tetrahedra each and an edge with a [NO₃]^? anion to form [(UO₂)(SeO₄)(NO₃)]^? chains parallel to the b axis. In the structure of 4 (triclinic, , a = 6.853(2), b = 10.537(3), c = 10.574(3) Å, α = 99.62(3), β = 94.45(3), γ = 100.52(3)°, V = 735.6(4) ų, R₁ = 0.045 for 2713 unique observed reflections), one symmetrically independent pentagonal [UO₇]^8? bipyramid shares corners with four [SeO₄]^2? tetrahedra to form the [(UO₂)(SeO₄)₂(H₂O)]^2? chains parallel to the a axis. A comparison to related uranyl compounds is given.     

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 and Crystal Structures of α‐ and β‐Mg2[(UO2)3(SeO4)5](H2O)16

Single crystals of α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ have been synthesized by evaporation from an aqueous solution of the ionic components. The structure of α‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ (monoclinic, C2/c, a = 19.544(3), b = 10.4783(11), c = 18.020(3) Å, β = 91.352(12)°, V = 3689.3(9) ų) has been solved by direct methods and refined to R₁ = 0.048 on the basis of 4338 unique observed reflections. The structure of β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ (orthorhombic, Pbcm, a = 10.3807(7), b = 22.2341(19), c = 33.739(5) Å, V = 7787.2(14) ų) has been solved by direct methods and refined to R₁ = 0.107 on the basis of 3621 unique observed reflections. The structures of α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ are based upon sheets with the chemical composition [(UO₂)₃(SeO₄)₅]^4‐. The sheets are formed by corner sharing between pentagonal bipyramids [UO₇]^8‐ and SeO₄^2‐ tetrahedra. In the α‐modification, the [(UO₂)₃(SeO₄)₅]^4‐ sheets are more or less planar and run parallel to (001). In the structure of the β‐modification, the uranyl selenate sheets are strongly corrugated and oriented parallel to (010). The [Mg(H₂O)₆]²⁺ polyhedra reside in the interlayers and provide three‐dimensional linkage of the uranyl selenate sheets via hydrogen bonding. In addition to H₂O groups attached to Mg²⁺ cations, both structures also contain H₂O molecules that are not bonded to any cation. The [(UO₂)₃(SeO₄)₅]^4‐ sheets in the structures of α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ represent two different structural isomers. The sequences of the orientations of the tetrahedra within the sheets can be described by their orientational matrices with their shortened forms ( ddudd □ /uu □ uud ) and ( dd □ dd □ uu □ uu □ /uuduumdduddm ) for α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆, respectively. A short review on the isomerism of [(UO₂)₃(TO₄)₅]^4‐ sheets (T = S, Cr, Se, Mo) is given.     

Influence of the Organic Species and Oxoanion in the Synthesis of two Uranyl Sulfate Hydrates, (H3O)2[(UO2)2(SO4)3­(H2O)]·7H2O and (H3O)2[(UO2)2(SO4)3(H2O)]·4H2O,and a Uranyl Selenate‐Selenite [C5H6N][(UO2)(SeO4)(HSeO3)]

Two uranyl sulfate hydrates, (H₃O)₂[(UO₂)₂(SO₄)₃(H₂O)] · 7H₂O (NDUS) and (H₃O)₂[(UO₂)₂(SO₄)₃(H₂O)] · 4H₂O (NDUS1), and one uranyl selenate‐selenite [C₅H₆N][(UO₂)(SeO₄)(HSeO₃)] (NDUSe), were obtained and their crystal structures solved. NDUS and NDUSe result from reactions in highly acidic media in the presence of L ‐cystine at 373 K. NDUS crystallized in a closed vial at 278 K after 5 days and NDUSe in an open beaker at 278 K after 2 weeks. NDUS1 was synthesized from aqueous solution at room temperature over the course of a month. NDUS, NDUS1, and NDUSe crystallize in the monoclinic space group P2₁/n, a = 15.0249(4) Å,b = 9.9320(2) Å, c = 15.6518(4) Å, β = 112.778(1)°, V = 2153.52(9) ų,Z = 4, the tetragonal space group P4₃2₁2, a = 10.6111(2) Å,c = 31.644(1) Å, V = 3563.0(2) ų, Z = 8, and in the monoclinic space group P2₁/n, a = 8.993(3) Å, b = 13.399(5) Å, c = 10.640(4) Å,β = 108.230(4)°, V = 1217.7(8) ų, Z = 4, respectively.The structural units of NDUS and NDUS1 are two‐dimensional uranyl sulfate sheets with a U/S ratio of 2/3. The structural unit of NDUSe is a two‐dimensional uranyl selenate‐selenite sheets with a U/Se ratio of 1/2. In‐situ reaction of the L ‐cystine ligands gives two distinct products for the different acids used here. Where sulfuric acid is used, only H₃O⁺ cations are located in the interlayer space, where they balance the charge of the sheets, whereas where selenic acid is used, interlayer C₅H₆N⁺ cations result from the cyclization of the carboxyl groups of L ‐cystine, balancing the charge of the sheets.     

Synthesis,Structure, and Photoluminescence Properties of an Organically‐Templated Uranyl Selenite

The organically‐templated uranyl selenite, (H₂en)[(UO₂)(SeO₃)(HSeO₃)](NO₃) · 0.5H₂O ( 1 ) (en = 1,2‐ethylenediamine) was synthesized and characterized by elemental analyses, IR spectroscopy, TG, and single‐crystal X‐ray diffraction. Compound 1 crystallizes in the orthorhombic system, space group Pbca, with a = 13.170(3) Å, b = 11.055(2) Å, c = 18.009(4) Å, V = 2621.8(9) ų, M = 1316.19, Z = 4, D_cal = 3.334 g · cm^–3, μ(Mo‐K_α) = 17.998 mm^–1, GOF = 1.059, R₁ = 0.0263, wR₂ = 0.0532 [I>2σ(I)]. The X‐ray diffraction analysis reveals that compound 1 has a three‐dimensional (3D) supramolecular structure. It contains negatively charged [UO₂(HSeO₃)(SeO₃)]^– inorganic anion layers and is balanced by [H₂en]²⁺ cations and NO₃^– anions located in the interlayers. Furthermore, the photoluminescence properties of 1 were investigated.     

Synthesis and structure of [UO2(SeO4)(C2H4N4)2] · 0.5H2O

The single-crystal X-ray diffraction analysis of [UO₂(SeO₄)(C₂H₄N₄)₂] · 0.5H₂O (I) is performed. The crystals are monoclinic: space group C2/c, Z = 8, a = 19.035(2), b = 7.1326(8), c = 21.477(2) Å, β = 109.683(4)°. The main structural units of the crystal are chains of [UO₂(SeO₄)(C₂H₄N₄)₂]. Compound I belongs to the crystal-chemical group AT³M ₂ ¹ (A = UO ₂ ²⁺ , T³ = SeO ₄ ^2? , M¹ is a cyanoguanidine molecule) of the uranyl complexes. The chains are united into three-dimensional framework through hydrogen bonds involving the oxygen atoms of the selenate and uranyl groups, the nitrogen atoms of cyanoguanidine, and the hydrogen atoms of the cyanoguanidine or water molecules.     

Isopropylammonium Layered Uranyl Chromates: Syntheses and Crystal Structures of [(CH3)2CHNH3]3[(UO2)3(CrO4)2O(OH)3] and[(CH3)2CHNH3]2[(UO2)2(CrO4)3(H2O)]

Two novel isopropylamine‐templated uranyl chromates, [(CH₃)₂CHNH₃]₃[(UO₂)₃(CrO₄)₂O(OH)₃] ( 1 ) and [(CH₃)₂CHNH₃]₂[(UO₂)₂(CrO₄)₃(H₂O)] ( 2 ) were prepared by hydrothermal method at 100 °C. The compounds were characterized by electron microprobe analysis and X‐ray diffraction crystal structure analysis [ 1 : trigonal, P31m, a = 9.646(4), c = 8.469(4) Å, V = 682.4(5) ų; 2 : monoclinic, P2₁/c, a = 11.309(3), b = 11.465(3), c = 17.055(5) Å, β = 99.150(6)°, V = 2183.2(11) ų]. The structure of 1 is based upon trimers of uranyl bipyramids interlinked by CrO₄ tetrahedra to form [(UO₂)₃(CrO₄)₂O(OH)₃]^3– layers, whereas, in the structure of 2 , UO₇ and UO₆(H₂O) pentagonal bipyramids are linked through CrO₄ tetrahedra into the [(UO₂)₂(CrO₄)₃(H₂O)]^2– layers. The structures show many similarities to related uranyl selenate compounds, thus providing additional data on similarities and differences between uranyl sulfates, chromates, selenates, and molybdates.     

Bidentate coordination of a diketo phosphorus ylide: synthesis and structure of [(C6H5)3PC(COCH3)(COC6H5)-κO,O′]UO2(NO3)2

A 1?:?1 chelate complex [(C₆H₅)₃PC(COCH₃)(COC₆H₅)-κO,O′]UO₂(NO₃)₂ has been synthesized by reaction of (C₆H₅)₃PC(COCH₃)(COC₆H₅) with UO₂(NO₃)₂?·?6H₂O in methanol at room temperature and characterized by elemental analysis, spectroscopy as well as by single-crystal X-ray diffraction. The complex crystallizes in P2₁/n space group with a?=?10.007(2)?Å, b?=?15.285(7)?Å, c?=?19.20(1)?Å, β?=?91.22(3)°, V?=?2936(2)?ų, Z?=?4, D _c?=?1.847?g?cm^?3. In the solid state structure, the dihedral angle [88.1(4)°] between the planes defined by the two quartets of atoms O1 O8 O2 O4 and O6 O5 O3 O7 is close to 90°, as expected for a triangulated dodecahedral geometry around uranium.     

Framework Polymorphism and Modular Crystal Structures of Uranyl Vanadates of Divalent Cations: Synthesis and Characterization of M(UO2)(V2O7) (M = Ca,Sr) and Sr3(UO2)(V2O7)2

Uranyl vanadate compounds with divalent cations, M(UO₂)(V₂O₇) (M = Ca, Sr) and Sr₃(UO₂)(V₂O₇)₂, were synthesized by flux crystal growth, and their crystal structures were solved using single‐crystal X‐ray diffraction data. Ca(UO₂)V₂O₇ and Sr(UO₂)V₂O₇ were synthesized from reactants with molar ratios M:U:V of 1:1:2 and identical heating conditions, and increasing the M:U:V ratio to 3:1:4 resulted in Sr₃(UO₂)(V₂O₇)₂. Crystallographic data for M(UO₂)V₂O₇ compounds are: a = 7.1774(18) Å, b = 6.7753(17) Å, c = 8.308(2) Å; V = 404.01(18) ų; space group Pmn2₁, Z = 2 for Ca; a = 13.4816(11) Å, b = 7.3218(6) Å, c = 8.4886(7) Å; V = 837.91(12) ų; space group Pnma, Z = 4 for Sr. Compound Sr₃(UO₂)(V₂O₇)₂ has a = 6.891(3) Å, b = 7.171(3) Å, c = 14.696(6) Å, α = 85.201(4)?, β = 78.003(4)?, γ = 89.188(4)?; V = 707.9(5) ų; space group P1 , Z = 2. The framework structure of Sr(UO₂)(V₂O₇) is related to that of Pb(UO₂)(V₂O₇) reported previously, while that of Ca(UO₂)(V₂O₇) has a different topology. The topological polymorphism of the [(UO₂)(V₂O₇)]‐type framework may be due to the differing ionic radii of the guest M²⁺ cations. Compound Sr₃(UO₂)(V₂O₇)₂ has a modular structure based on two different types of electroneutral layers: [Sr(UO₂)(V₂O₇)] and [Sr₂(V₂O₇)]. Structural complexities were calculated, and Raman spectra were collected and their peaks were assigned.     

Synthesis and structure of Na[UO2(SeO3)(HSeO3)] · 4H2O

Compound Na[UO₂(SeO₃)(HSeO₃)] · 4H₂O (I) has been synthesized and studied by single-crystal X-ray diffraction. The crystals of I are monoclinic with the unit cell parameters a = 8.8032(5) Å, b = 10.4610(7) Å, c = 13.1312(7) Å, β = 105.054(2)°, space group P2₁/n, Z = 4, V = 1167.76(12) ų, R = 0.0394. The main structural units of crystals I are the [UO₂(SeO₃)(HSeO₃)]^? layers belonging to the AT³B² crystal-chemical group (A = UO ₂ ²⁺ , T³ = SeO ₃ ^2? , B² =HSeO ₃ ^? ) of the uranyl complexes. The sodium ions are linked with oxygen atoms of two uranyl ions of the same layer and with four water molecules. Electroneutral packets that formed are linked into a three-dimensional framework through a system of hydrogen bonds.     

Crystal structure of Na2[(UO2)2(SeO4)3(H2O)2] · 6.5H2O

The compound Na₂[(UO₂)₂(SeO₄)₃(H₂O)₂] · 6.5H₂O (I) is studied using X-ray diffraction. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 19.7366(8) Å, b = 10.8206(4) Å, c = 21.3577(8) Å, β = 103.4311(1)°, Z = 4, and the space group P2₁/c, R ₁ = 0.0379. Compound I is found to be a representative of the crystal-chemical group A₂T ₂ ³ B²M ₂ ¹ (A = UO ₂ ²⁺ ) of uranyl complexes and contains the cage group [(UO₂)₂(SeO₄)₃(H₂O)₂]^2?.     

Nd2(SeO3)2(SeO4) · 2H2O – a Mixed‐Valence Compound containing Selenium in the Oxidation States +IV and +VI

Pale pink crystals of Nd₂(SeO₃)₂(SeO₄) · 2H₂O were synthesized under hydrothermal conditions from H₂SeO₃ and Nd₂O₃ at about 200 °C. X‐ray diffraction on powder and single‐crystals revealed that the compound crystallizes with the monoclinic space group C 2/c (a = 12.276(1) Å, b = 7.0783(5) Å, c = 13.329(1) Å, β = 104.276(7)°). The crystal structure of Nd₂(SeO₃)₂(SeO₄) · 2H₂O is an ordered variant of the corresponding erbium compound. Eight oxygen atoms coordinate the Nd^III atom in the shape of a bi‐capped trigonal prism. The oxygen atoms are part of pyramidal (Se^IVO₃)^2? groups, (Se^VIO₄)^2? tetrahedra and water molecules. The [NdO₈] polyhedra share edges to form chains oriented along [010]. The selenate ions link these chains into layers parallel to (001). The layers are interconnected by the selenite ions into a three‐dimensional framework. The dehydration of Nd₂(SeO₃)₂(SeO₄) · 2H₂O starts at 260 °C. The thermal decomposition into Nd₂SeO₅, SeO₂ and O₂ at 680 °C is followed by further loss of SeO₂ leaving cubic Nd₂O₃.     

Polymorphism in Alkali Metal Uranyl Nitrates: Synthesis and Crystal Structure of γ‐K(UO2)(NO3)3

Single crystals of γ‐K(UO₂)(NO₃)₃ were prepared from aqueous solutions by evaporation. The crystal structure [orthorhombic, Pbca (61), a = 9.2559(3) Å, b = 12.1753(3) Å, c = 15.8076(5) Å, V = 1781.41(9) Å³, Z = 8] was determined by direct methods and refined to R₁ = 0.0267 on the basis of 3657 unique observed reflections. The structure is composed of isolated anionic uranyl trinitrate units, [(UO₂)(NO₃)₃]^–, that are linked through eleven‐coordinated K⁺ cations. Both known polymorphs of K(UO₂)(NO₃)₃ (α‐ and γ‐phases) can be considered as based upon sheets of isolated complex [(UO₂)(NO₃)₃]^– ions separated by K⁺ cations. The existence of polymorphism in the two K[UO₂(NO₃)₃] polymorphs is due to the different packing modes of uranyl trinitrate clusters that adopt the same two‐dimensional but different three‐dimensional arrangements.     

Synthesis, structure, and physicochemical properties of K[VO2(SeO4)(H2O)] and K[VO2(SeO4)(H2O)2] · H2O

The vanadium(V) complexes K[VO₂(SeO₄)(H₂O)] and K[VO₂(SeO₄)(H₂O)₂] · H₂O were synthesized using original procedures; their physicochemical properties were studied, and the crystal structure was determined on the basis of X-ray diffraction and neutron diffraction data. The structure of K[VO₂(SeO₄)(H₂O)₂] · H₂O is composed of VO₆ octahedra connected to form infinite chains by bridging SeO₄ tetrahedra. Each VO₆ tetrahedron has short terminal V-O bonds forming the bent dioxovanadium group VO₂⁺ The unit cell parameters of K[VO₂(SeO₄)(H₂O)₂] · H₂O are a = 6.4045(1) ?, b = 9.9721(2) ?, c = 6.6104(1) ?, β = 107.183(1)°, V = 403.34 ?³, Z = 2, monoclinic system, space group P2₁. The complex K[VO₂(SeO₄)(H₂O)] forms a two-dimensional layered structure composed of highly distorted VO₆ octahedra having two short terminal V-O bonds and SeO₄ groups coordinated simultaneously by three vanadium atoms. This compound crystallizes in the monoclinic system (space group P2₁/c): a = 7.3783(1) ?, b = 10.5550(2) ?, c = 10.3460(2) ?, β = 131.625(1)°, V = 602.894(5) ?³, Z= 4. The vibrational spectra of the studied compounds are fully consistent with their structural features.     

Structure and some properties of [UO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)(C<Subscript>5</Subscript>H<Subscript>12</Subscript>N<Subscript>2</Subscript>O)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)]

The complex [UO₂(SeO₄)(C₅H₁₂N₂O)₂(H₂O)] (I) was synthesized and studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are orthorhombic: a = 13.1661(3) Å, b = 16.4420(5) Å, c = 17.4548(6) Å, Pbca, Z = 8, R = 0.0423. The structural units of crystal I are chains with the composition coinciding with that of the compounds of the AB₂M ₃ ¹ crystal chemical group of the uranyl complexes (A = UO ₂ ²⁺ , B² = SeO ₄ ^2? , M¹ = C₅H₁₂N₂O and H₂O).     

Crystal structure of Na6[(UO2)3O(OH)3(SeO4)2]2 · 10H2O

The complex Na₆[(UO₂)₃O(OH)₃(SeO₄)₂]₂ · 10H₂O (I) is synthesized and studied by X-ray diffraction. The compound crystallizes in the orthorhombic crystal system with the unit cell parameters: a = 14.2225(7) Å, b = 18.3601(7) Å, c = 16.5406(6) Å, V = 4319.2(3) ų, Z = 4, space group Cmcm, R ₁ = 0.0406. Compound I is found to be a representative of the crystal-chemical group A₃M³M² ₃T³ ₂ (A = UO²⁺ ₂, M³ = O^2?, M² = OH^?, T³ = SeO^2? ₄) of the uranyl complexes; it contains layer uranium-containing groups [(UO₂)₃O(OH)₃(SeO₄)₂]^3?. These layers linked to form a three-dimensional cage through bonds formed by the sodium atoms with the oxygen atoms of the uranyl ions and SeO₄ groups that belong to different layers.     

Bildung oktaedrischer Komplexe durch cis-Addition an planar-quadratisches Bis(oxamidoximato)nickel(II): drei Strukturbeispiele

Formation of Octahedral Complexes via cis-Addition to Square Planar Bis (oxamideoximato)nickel(II): Three Structure Examples In the reaction of orange square planar bis(oxamide oximato)nickel(II) with acids, blue to blue-green octahedral complexes are formed with neutral oxamide oximide ligands and two acid anions in cis-positions. Three compounds are described: cis-dichlorobis(oxamide oxime)nickel(II) ( 1 ), NiCl₂(C₂H₆N₄O₂)₂, M_r = 365.81, monoclinic P2₁/n, a = 6.641(2), b = 14.086(4), c = 13.473(3) Å, β = 96.26(2)°, V = 1 252.8 ų, Z = 4, d_c = 1.94 gcm^?3, final R_w = 0.031 for 4090 reflections. In cis-di(sulfanilato)bis(oxamide oxime)nickel(II) dihydrate ( 2 ) one sulfanilic anion coordinates via the sulfonic acid group, the other one via the amino group; Ni(C₆H₆NO₃S)₂(C₂H₆N₄O₂)₂ · 2 H₂O, M_r = 675.30, monoclinic P2₁, a = 6.879(3), b = 14.305(5), c = 13.930(5) Å, β = 103.62(4)°, V = 1332 Å, Z = 2, d_c = 1.68 gcm^?3, R = 0.067 for 2693 reflections. In catena-μ-(phthalato)bis(oxamide oxime)nickel(II) tetrahydrate ( 3 ) bidentate bridging phthalate anions lead to chain formation; Ni(C₈H₄O₄)(C₂H₆N₄O₂)₂ · 4H₂O, M_r = 531.09, monoclinic P2₁/c, a = 10.633(8), b = 11.324(5), c = 17.680(14) Å, β = 98.25(7)°, V = 2107 ų, Z = 4, d_c = 1.67 gcm^?3. Final R = 0.110 for 3290 reflections.     

Synthesis and crystal structure of (NH<Subscript>4</Subscript>)(CN<Subscript>3</Subscript>H<Subscript>6</Subscript>)[UO<Subscript>2</Subscript>(SeO<Subscript>3</Subscript>)<Subscript>2</Subscript>]

Single crystals of (NH₄)(CN₃H₆)[UO₂(SeO₃)₂] (I) are synthesized and studied by X-ray diffraction analysis. The compound crystallizes in the triclinic crystal system with the unit cell parameters: a = 7.0051(2) Å, b = 9.4234(3) Å, c = 9.5408(3) Å, α = 88.727(1)°, β = 70.565(1)°, γ= 77.034(1)°, space group P ₁, Z = 2, R = 0.0224. The main structural units of crystals I are the [UO₂(SeO₃)₂]^2? chains of the crystal-chemical group AB²B₁₁ (A = UO ₂ ²⁺ , B₂= SeO₃ ^2?, B₁₁= SeO₃ ^2?) of the uranyl complexes. The uranium-containing complexes are joined into a three-dimensional framework by the ammonium and guanidinium ions and a system of hydrogen bonds.     

Incorporation of Sulfate or Selenate Groups into Oxotellurates(IV): I. Calcium,Cadmium, and Strontium Compounds

Seven new mixed oxochalcogenate compounds in the systems M^II/X^VI/Te^IV/O/(H), (M^II = Ca, Cd, Sr; X^VI = S, Se) were obtained under hydrothermal conditions (210 °C, one week). Crystal structure determinations based on single‐crystal X‐ray diffraction data revealed the compositions Ca₃(SeO₄)(TeO₃)₂, Ca₃(SeO₄)(Te₃O₈), Cd₃(SeO₄)(Te₃O₈), Cd₃(H₂O)(SO₄)(Te₃O₈), Cd₄(SO₄)(TeO₃)₃, Cd₅(SO₄)₂(TeO₃)₂(OH)₂, and Sr₃(H₂O)₂(SeO₄)(TeO₃)₂ for these phases. Peculiar features of the crystal structures of Ca₃(SeO₄)(TeO₃)₂, Ca₃(SeO₄)(Te₃O₈), Cd₃(SeO₄)(Te₃O₈), Cd₃(H₂O)(SO₄)(Te₃O₈), and Sr₃(H₂O)₂(SeO₄)(TeO₃)₂ are metal‐oxotellurate(IV) layers connected by bridging XO₄ tetrahedra and/or by hydrogen‐bonding interactions involving hydroxyl or water groups, whereas Cd₄(SO₄)(TeO₃)₃ and Cd₅(SO₄)₂(TeO₃)₂(OH)₂ crystallize as framework structures. Common to all crystal structures is the stereoactivity of the Te^IV electron lone pair for each oxotellurate(IV) unit, pointing either into the inter‐layer space, or into channels and cavities in the crystal structures.     

Complex Topology of Uranyl Polyphosphate Frameworks: Crystal Structures of α‐, β‐K[(UO2)(P3O9)] and K[(UO2)2(P3O10)]

Three new uranyl polyphosphates, α‐K[(UO₂)(P₃O₉)] ( 1 ), β‐K[(UO₂)(P₃O₉)] ( 2 ), and K[(UO₂)₂(P₃O₁₀)] ( 3 ), were prepared by high‐temperature solid‐state reactions. The crystal structures of the compounds have been solved by direct methods: 1 – monoclinic, P2₁/m, a = 8.497(1), b = 15.1150(1), c = 14.7890(1) Å, β = 91.911(5)°, V = 1898.3(3) ų, Z = 4, R₁ = 0.0734 for 4181 unique reflections with |F₀| ≥ 4σ_F; 2 – monoclinic, P2₁/n, a = 8.607(1), b = 14.842(2), c = 14.951(1) Å, β = 95.829(5)°, V = 1900.0(4) ų, Z = 4, R₁ = 0.0787 for 3185 unique reflections with |F₀| ≥ 4σ_F; 3 – Pbcn, a = 10.632(1), b = 10.325(1), c = 11.209(1) Å, V = 1230.5(2) ų, Z = 4, R₁ = 0.0364 for 1338 unique reflections with |F₀| ≥ 4σ_F. In the structures of 1 and 2 , phosphate tetrahedra share corners to form infinite [PO₃]^? chains, whereas, in the structure of 3 , tetrahedra form linear [P₃O₁₀]^5? trimers. The structures are based upon 3‐D frameworks of U and P polyhedra linked by sharing common O corners. The infinite [PO₃]^? chains in the structures of 1 and 2 are parallel to [100] and [–101], respectively. The uranyl polyphosphate frameworks are occupied by host K⁺ cations.