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.     

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 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.     

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.     

Hydrothermal Synthesis and Crystal Structures of Na2Be3(SeO3)4·H2O and Cs2[Mg(H2O)6]3(SeO3)4

The selenites, Na₂Be₃(SeO₃)₄ · H₂O and Cs₂[Mg(H₂O)₆]₃(SeO₃)₄, were synthesized under hydrothermal conditions. The crystal structures of Na₂Be₃(SeO₃)₄ · H₂O and Cs₂[Mg(H₂O)₆]₃(SeO₃)₄ were determined by single‐crystal X‐ray diffractions. Na₂Be₃(SeO₃)₄ · H₂O crystallizes in the triclinic space group P1 (no. 2) with unit cell parameters a = 4.8493(9), b = 12.013(2), c = 12.077(2) Å, and Z = 2, whereas Cs₂[Mg(H₂O)₆]₃(SeO₃)₄ crystallizes in the monoclinic space group C2/m (no. 12) with lattice cell parameters a = 12.596(6), b = 7.297(4), c = 16.914(8) Å, and Z = 2. Na₂Be₃(SeO₃)₄ · H₂O features a three‐dimensional open framework structure formed by BeO₄ tetrahedra and SeO₃ trigonal pyramids. Na cations and H₂O molecules are located in different tunnels. Cs₂[Mg(H₂O)₆]₃(SeO₃)₄ has a structure composed of isolated [Mg(H₂O)₆] octahedra and SeO₃ trigonal pyramids interacted by hydrogen bonds, and Cs cations are resided in‐between. Both compounds were characterized by thermogravimetric analysis and FT‐IR spectroscopy.     

Crystal structure of (C2H7N4O)2[UO2(C2O4)2(H2O)]

The single crystals of (C₂H₇N₄O)₂[UO₂(C₂O₄)₂(H₂O)] were studied by X-ray diffraction. The crystals are monoclinic, space group Pn, Z = 2, unit cell parameters: a = 9.4123(2) Å, b = 8.4591(2) Å, c = 11.8740(3) Å, β = 105.500(10)°, V = 911.02(4) ų. The main structural units of the crystals of I are islet complex groups [UO₂(C₂O₄)₂(H₂O)]^2? corresponding to the crystal chemical group AB ₂ ⁰¹ M¹ (A = UO UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M = H₂O) of uranyl complexes. Uranium-containing mononuclear complexes are connected into a three-dimensional framework through the electrostatic interactions and hydrogen bonding system involving carbamyolguanidinium ions.     

The Rb analogue of grimselite,Rb6Na2[(UO2)(CO3)3]2(H2O)

The crystal structure of the Rb analogue of grimselite, rubidium sodium uranyl tricarbonate hydrate, Rb₆Na₂[(UO₂)(CO₃)₃]₂(H₂O), consists of a uranyl hexagonal bipyramid that shares three non‐adjacent equatorial edges with carbonate triangles, resulting in a uranyl tricarbonate cluster of composition [(UO₂)(CO₃)₃)]. These uranyl tricarbonate clusters form layers perpendicular to [001] and are interconnected by NaO₈ polyhedra. The title compound is isostructural with grimselite, with a reduced occupancy of the H₂O site (25% versus 50% in grimselite).     

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.     

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.     

Amine‐Templated Uranyl Selenates with Layered Structures. I Structural Diversity of Sheets with a U:Se ratio of 1:2

Crystals of four amine‐templated layered uranyl selenates, [C₂H₁₀N₂][(UO₂)(SeO₄)₂(H₂O)](H₂O) ( 1 ), [CH₆N₃]₂[(UO₂)(SeO₄)₂(H₂O)](H₂O)_1.5 ( 2 ), [C₄H₁₂N]₂[(UO₂)(SeO₄)₂(H₂O)] ( 3 ), and [CH₆N₃]₃[(UO₂)₂(SeO₄)₂(H(SeO₄)₂)](H₂O)₂ ( 4 ) were prepared by evaporation from aqueous solution of uranyl nitrate, selenic acid and the respective amine. The structures of all four compounds have been solved by direct methods. The structures of 1 (monoclinic, C2/c, a = 11.787(2), b = 7.7007(10), c = 16.600(3) Å, β = 102.016(14)°, V = 1473.7(4) ų, R₁ = 0.037 for 1743 unique observed reflections), 2 (monoclinic, C2/c, a = 37.314(4), b = 7.1771(6), c = 13.2054(14) Å, β = 109.267(8)°, V = 3338.4(6) ų, R₁ = 0.088 for 3005 unique observed reflections) and 3 (monoclinic, C2/c, a = 27.212(10), b = 7.372(3), c = 23.113(7) Å, β = 117.75(2)°, V = 4103(3) ų, R₁ = 0.073 for 2111 unique observed reflections) are based on sheets of the composition [(UO₂)(SeO₄)₂(H₂O)]^2? consisting of pentagonal [UO₇]^8? pentagonal bipyramids linked via [SeO₄]^2? tetrahedra. The sheets have the same chemical composition but different topologies. The structure of 4 (orthorhombic, P2₁2₁2₁, a = 10.7261(9), b = 13.918(2), c = 18.321(2) Å, V = 2735.1(5) ų, R₁ = 0.050 for 5683 unique observed reflections) contains [(UO₂)₂(SeO₄)₂(H(SeO₄)₂)]^3? sheets parallel to (001). In all four structures, the layers are connected via protonated amine and H₂O molecules.     

Competitive Coordination of the Uranyl Ion by Perchlorate and Water ‐ The Crystal Structures of UO2(ClO4)2·3H2O and UO2(ClO4)2·5H2O and a Redetermination of UO2(ClO4)2·7H2O

By slow evaporation of solutions containing UO₂(ClO₄)₂ and an excess of HClO₄, single crystals of [UO₂(ClO₄)₂(H₂O)₃] ( 1 ) and [UO₂(H₂O)₅](ClO₄)₂ ( 2 ) were obtained and their structures were determined. From similar solutions prepared from stoichiometric amounts of UO₃ and perchloric acid, crystals of [UO₂(H₂O)₅](ClO₄)₂·2H₂O ( 3 ) were obtained. The trihydrate (monoclinic, P2₁/c, a = 545.44(1) pm, b = 1811.09(5) pm, c = 1032.46(2) pm, β = 90.016(1)°) consists of uranyl ions, which are coordinated by two monodentate perchlorate ions and three water molecules. The pentahydrate (monoclinic, P2₁/n, a = 529.35(2) pm, b = 1645.43(6) pm, c = 1480.18(6) pm, β = 99.847(1)°) contains uranyl ions coordinated by five water molecules. The same structural unit can be found in the heptahydrate, whose structure was re‐determined (orthorhombic, Pbcn, a = 920.9(3) pm, b = 1067.9(3) pm, c = 1445.7(3) pm). In this structure, two molecules of water of crystallization are present.     

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.     

Competitive Coordination of the Uranyl ion by Perchlorate and Water – The Crystal Structures of UO2(ClO4)2·3H2O and UO2(ClO4)2·5H2O and a Redetermination of UO2(ClO4)2·7H2O (Z. Anorg. Allg. Chem. 2003, 629, 1012–1016)

In the article “Competitive Coordination of the Uranyl ion by Perchlorate and Water – The Crystal Structures of UO₂(ClO₄)₂·3H₂O and UO₂(ClO₄)₂·5H₂O and a Redetermination of UO₂(ClO₄)₂·7H₂O” (Z. Anorg. Allg. Chem. 2003 , 629, 1012–1016), some wrong parameters and bond lengths for UO₂(ClO₄)₂·7H₂O were given in table 1 and table 3 The correct parameters are: a = 1449.5(2) pm, b = 921.6(1) pm, c = 1067.5(2) pm, V = 1422.5(4)·10⁶ pm³, ρ = 2.712 g·cm^?3, μ = 119 cm^?1. The corrected bond lengths for this structure are U–O(1) 175.8(5) pm, U–O(2) 239.1(5) pm, U–O(3) 240.8(5), U–O(4) 242.0(7). A cif file with the correct data has been deposited with the ICSD.     

Crystal Structures of [Mn2(H2O)4(phen)2(C4H4O4)2] · 2 H2O and [Mn(phen)2(H2O)2][Mn(phen)2(C4H4O4)](C4H4O4) · 7 H2O

Reactions of 1,10‐phenanthroline monohydrate, Na₂C₄H₄O₄ · 6 H₂O and MnSO₄ · H₂O in CH₃OH/H₂O yielded a mixture of [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] · 2 H₂O ( 1 ) and [Mn(phen)₂(H₂O)₂][Mn(phen)₂(C₄H₄O₄)](C₄H₄O₄) · 7 H₂O ( 2 ). The crystal structure of 1 (P1 (no. 2), a = 8.257(1) Å, b = 8.395(1) Å, c = 12.879(2) Å, α = 95.33(1)°, β = 104.56(1)°, γ = 106.76(1)°, V = 814.1(2) ų, Z = 1) consists of the dinuclear [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] molecules and hydrogen bonded H₂O molecules. The centrosymmetric dinuclear molecules, in which the Mn atoms are octahedrally coordinated by two N atoms of one phen ligand and four O atoms from two H₂O molecules and two bis‐monodentate succinato ligands, are assembled via π‐π stacking interactions into 2 D supramolecular layers parallel to (101) (d(Mn–O) = 2.123–2.265 Å, d(Mn–N) = 2.307 Å). The crystal structure of 2 (P1 (no. 2), a = 14.289(2) Å, b = 15.182(2) Å, c = 15.913(2) Å, α = 67.108(7)°, β = 87.27(1)°, γ = 68.216(8)°, V = 2934.2(7) ų, Z = 2) is composed of the [Mn(phen)₂(H₂O)₂]²⁺ cations, [Mn(phen)₂(C₄H₄O₄)] complex molecules, (C₄H₄O₄)^2– anions, and H₂O molecules. The (C₄H₄O₄)^2– anions and H₂O molecules form 3 D hydrogen bonded network and the cations and complex molecules in the tunnels along [001] and [011], respectively, are assembled via the π‐π stacking interactions into 1 D supramolecular chains. The Mn atoms are octahedrally coordinated by four N atoms of two bidentate chelating phen ligands and two water O atoms or two carboxyl O atoms (d(Mn–O) = 2.088–2.129 Å, d(Mn–N) = 2.277–2.355 Å). Interestingly, the succinato ligands in the complex molecules assume gauche conformation bidentately to chelate the Mn atoms into seven‐membered rings.     

K2[(UO2)As2O7] – the First Uranium Polyarsenate

Yellowish crystals of K₂[(UO₂)As₂O₇] ( 1 ) have been synthesized by solid‐state reactions method. The structure of 1 [orthorhombic, Pmmn, a = 12.601(2), b = 13.242(2), c = 5.621(1) Å, V = 937.9(3) ų, Z = 4] has been solved by direct methods and refined to R₁ = 0.049, wR₂ = 0.1060 for 1059 observed reflections. The structure of 1 is based upon [(UO₂)As₂O₇]^2? sheets formed by corner sharing between [UO₆]^6? distorted octahedra and [As₂O₇]^4? polyarsenate groups. The K⁺ cations are either in eightfold or tenfold coordination and are located between the sheets. The topology of the uranyl arsenate sheet is related to silicate minerals of the melilite group and related synthetic silicate, aluminate and germanate compounds.     

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.     

A Bis(p-tert-butyloctahomotetraoxacalix[8]arene) Capsule with [(UO2)2(OH)2] Links and a Disordered [Rb4(H2O)4] Inner Core

p-tert-Butyloctahomotetraoxacalix[8]arene (LH⁸) reacts with uranyl nitrate hexahydrate in the presence of rubidium hydroxide to give a mixed complex that can be viewed as a tetrauranate dimer [(UO²)⁴(LH⁴)²(OH)⁴] containing four disordered rubidium ions and water molecules. Two uranyl ions are complexed in an “external” fashion by each macrocycle, each of them bound to two phenoxide groups and one ether group, as well as to two bridging hydroxide ions. The latter ensure the formation of a dimeric capsule that contains the disordered set of alkali metal ions. Apart from water molecules, the Rb⁺ ions are bound to the uranyl oxo groups directed towards the inner cavity, and to phenol and ether oxygen atoms from the macrocycle. The resulting octanuclear complex presents an unprecedented geometry evidencing the assembling potential of uranyl ions.

p-tert-Butyloctahomotetraoxacalix[8]arene (LH₈) reacts with uranyl nitrate hexahydrate in the presence of rubidium hydroxide to give a mixed complex that can be viewed as a tetrauranate dimer [(UO₂)₄(LH₄)₂(OH)₄] containing four disordered rubidium ions and water molecules. Two uranyl ions are complexed in an “external” fashion by each macrocycle, each of them bound to two phenoxide groups and one ether group, as well as to two bridging hydroxide ions. The latter ensure the formation of a dimeric capsule that contains the disordered set of alkali metal ions. Apart from water molecules, the Rb^+| ions are bound to the uranyl oxo groups directed towards the inner cavity, and to phenol and ether oxygen atoms from the macrocycle. The resulting octanuclear complex presents an unprecedented geometry evidencing the assembling potential of uranyl ions.     

Influence of the Counterions on the Structures of Ternary Zn/Sn/Se Anions: Synthesis and Properties of [Rb10(H2O)14.5][Zn4(μ4‐Se)2(SnSe4)4] and [Ba5(H2O)32][Zn5Sn(μ3‐Se)4(SnSe4)4]

Reactions of rubidium or barium salts of the ortho‐selenostannate anion, [Rb₄(H₂O)₄][SnSe₄] ( 1 ) or [Ba₂(H₂O)₅][SnSe₄] ( 2 ) with Zn(OAc)₂ or ZnCl₂ in aqueous solution yielded two novel compounds with different ternary Zn/Sn/Se anions, [Rb₁₀(H₂O)_14.5][Zn₄(μ₄‐Se)₂(SnSe₄)₄] ( 3 ) and [Ba₅(H₂O)₃₂][Zn₅Sn(μ₃‐Se)₄(SnSe₄)₄] ( 4 ). 1 – 4 have been determined by means of single crystal X‐ray diffraction: 1 : triclinic space group lattice dimensions at 203 K: a = 8.2582(17) Å, b = 10.634(2) Å, c = 10.922(2) Å, α = 110.16(3)°, β = 91.74(3)°, γ = 97.86(3)°, V = 888.8(3) ų; R₁ [I > 2σ(I)] = 0.0669; wR₂ = 0.1619; 2 : orthorhombic space group Pnma; lattice dimensions at 203 K: a = 17.828(4) Å, b = 11.101(2) Å, c = 6.7784(14) Å, V = 1341.5(5) ų; R₁ [I > 2σ(I)] = 0.0561; wR₂ = 0.1523; 3 : triclinic space group ; lattice dimension at 203 K: a = 17.431(4) Å, b = 17.459(4) Å, c = 22.730(5) Å, α = 105.82(3)°, β = 99.17(3)°, γ = 90.06(3)°, V = 6563.1(2) ų; R₁ [I > 2σ(I)] = 0.0822; wR₂ = 0.1782; 4 : monoclinic space group P2₁/c; lattice dimensions at 203 K: a = 25.231(5) Å, b = 24.776(5) Å, c = 25.396(5) Å, β = 106.59(3)°, V = 15215.0(5) ų; R₁ [I > 2σ(I)] = 0.0767; wR₂ = 0.1734. The results serve to underline the crucial role of the counterion for the type of ternary anion to be observed in the crystal. Whereas Rb⁺(aq) stabilizes a P1‐type Zn/Sn/Se supertetrahedron in 3 like K⁺, the Ba²⁺(aq) ions better fit to an anionic T3‐type Zn/Sn/Se cluster arrangement as do Na⁺ ions. It is possible to estimate a radius:charge ratio for the stabilization of the two structural motifs.     

Selenious Acid as a Ligand: Molecular and Crystal Structure of [Co(H2O)2Cl2(H2SeO3)2]

[Co(H₂O)₂Cl₂(H₂SeO₃)₂] (monoclinic, P2₁/c, Z = 2, a = 519.82(5), b = 1462.6(1), c = 643.09(7) pm, β = 92.51(1)°, R_all = 0.0583) was obtained from CoCl₂ and H₂SeO₃ as purple plate–shaped single crystals. In the compound, the Co²⁺ ions are octahedrally coordinated by two Cl^? ions, two H₂O molecules, and two monodentate H₂SeO₃ molecules, leading to neutral complexes [Co(H₂O)₂Cl₂(H₂SeO₃)₂]. They are connected by hydrogen bonds involving both chlorine and oxygen atoms as acceptor atoms.