Space Group Pbcm Research Articles

K5(UO2)2[Si4O12(OH)]: A Uranyl Silicate Containing Chains of Four Silicate Tetrahedra Linked by SiO×××HOSi Hydrogen Bonds.

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Synthesis and crystal structure of a new ternary compound Ca 4Al 3Mg

The ternary compound Ca 4Al 3Mg was successfully synthesized by induction melting of appropriate amounts of pure metals followed by annealing at 773 K for 14 days. The crystal structure was determined by X-ray powder diffraction. Ca 4Al 3Mg crystallizes in space group Pbcm (No. 57); cell parameters: a = 6.1792(1) Å, b = 24.2113(5) Å, c = 5.8864(1) Å; Z = 4. This structure can be built up of the alternating layers of two types of chains. The first type of chains consists of Al 3 triangles sharing one corner and the second one contains AlMg 2 triangles sharing one of the Mg corners. Both of them run along the crystallographic c-axis, forming atomic layers normal to the b-axis.

New Ternary Compounds in the Sm—Rh—Ge System.

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K5(UO2)2[Si4O12(OH)]: A Uranyl Silicate Containing Chains of Four Silicate Tetrahedra Linked by SiO···HOSi Hydrogen Bonds

A new uranium(VI) silicate, K5(UO2)2[Si4O12(OH)], has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the orthorhombic space group Pbcm (No. 57) with a = 13.1274(7) A, b = 12.2635(7) A, c = 22.233(1) A, and Z= 8. Its structure consists of unbranched chains of four silicate tetrahedra extending along the b axis linked together via corner-sharing by UO6 tetragonal bipyramids to form a 3-D framework, which delimits intersecting channels along the c and b axes to accommodate K+ cations. A hydrogen atom is bonded to a terminal oxygen of a terminal silicate in the oligosilicate anion. Adjacent chains are linked along the b axis by hydrogen bonds. The sample shows a resonance at 14.7 ppm the 1H MAS NMR spectrum, which is assigned to the SiO...HOSi hydrogen bond. A comparison of uranyl silicate structures is made.

Organically Templated Zinc Selenites: MIL‐86 or [H2N(CH2)2NH2] 2×Zn4(SeO3)4 and MIL‐87 or [H3N(CH2)3NH3] 4×Zn4(SeO3)8.

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Synthesis and crystal structure of catena- -chloro-bis(acetonitrile)copper(I) [(H3CCN)2CuCl]

The new crystalline compound of catena-μ-chloro-bis(acetonitrile)copper(I) [(H3CCN)2 CuCl]∞ has been synthesized and structurally characterized by X-ray crystallography. The compound is an infinite polymeric chain in which chlorides bridge the coppers. Copper exhibits tetrahedral coordination geometry with two acetonitrile molecules acting as coordinating ligands. The compound crystallizes in the orthorhombic Pbcm space group with a = 12.585(3) A, b = 7.496(2) A, and c = 7.275(2) A.

Does hydrogen bonding matter in crystal engineering? Crystal structures of salts of isomeric ions.

The preparation and structure determinations of the crystalline salts [3,3'-H(2)bipy][PtCl(4)] (2), [2,2'-H(2)bipy][PtCl(4)] (3) and [1,4'-Hbipy][PtCl(4)] (4) and [3,3'-H(2)bipy][SbCl(5)] (6) and [1,4'-Hbipy][SbCl(5)] (8) are reported. In addition a redetermination of the structure of the metastable salt [4,4'-H(2)bipy][SbCl(5)] (5 b) in the corrected space group Pbcm is described. These structures are compared to those of the known salt [4,4'-H(2)bipy][PtCl(4)] (1), the stable triclinic form of [4,4'-H(2)bipy][SbCl(5)] (5 a) and [2,2'-H(2)bipy][SbCl(5)] (7). In the case of the salts of the rigid [PtCl(4)](2-) ion, structures 2, 3 and 4 are essentially isostructural despite the differing hydrogen-bonding capability of the cations. Similarly, among the salts of [SbCl(5)](2-) ions, structures 7 and 8 are essentially isostructural. Structure 6 differs from these in having a differing pattern of aggregation of the [SbCl(5)](2-) ions to form polymeric rather than tetrameric units. It is evident that local hydrogen-bonding interactions, although significant, are not the only or even the decisive influence on the crystal structures formed by these salts. These observations are not in good accord with the heuristic "sticky tecton" or supramolecular synthon models for synthetic crystallography or crystal engineering.

Preparation and Crystal Structure Analyses of Compounds in the Systems HgO/MXO4/H2O (M = Co, Zn, Cd; X = S, Se)

AbstractDuring phase formation experiments under hydrothermal conditions (250 °C, 5d) in the systems HgO/MXO4/H2O (M = Co, Zn, Cd; X = S, Se), single crystals of the mercuric compounds (CdSO4)2(HgO)2H2O (I), (CdSeO4)2(HgO)2H2O (II), (CdSeO4)Hg(OH)2 (III), (CoSO4)2(HgO)2H2O (IV), (ZnSO4)2(HgO)2H2O (V), (ZnSeO4)2(HgO)2H2O (VI), and the mixed‐valent (ZnSeIVO3)(ZnSeVIO4)HgI2(OH)2 (VII) were obtained. The crystal structure determinations from X‐ray diffraction data revealed four unique structure types for these compounds. I and II crystallise isotypically in space group P2/n (a ≈ 7.85, b ≈ 6.28, c ≈ 10.5Å, β ≈ 102°), compound III crystallises in space group C2/m (a = 10.540(2), b = 9.0120(8), c = 6.1330(12)Å, β = 100.45(3)°), and the isotypic compounds IV, V and VI crystallise in space group Pbcm (a ≈ 6.15, b ≈ 11.3, c ≈ 13.1Å). Common with these three structure types are distorted octahedral [MO6] and tetrahedral XO4 building units which are organised in a layered assembly. Within the layers H bonding of OH groups or H2O molecules of the [MO6] octahedra leads to an additional stabilisation. Adjacent layers are separated by mercury atoms which are linearly bonded to two O atoms at short distances, forming either interconnecting [O‐Hg‐O] units which are part of [O‐Hg‐O]∞ zig‐zag chains, or single [HO‐Hg‐OH] units (realised in compound III). VII is the only compound with mercury in oxidation state +1. It crystallises in space group C2/m (a = 17.342(3), b = 6.1939(10), c = 4.4713(8)Å, β = 90.154(3)°) and is made up of Hg22+ dumbbells, [ZnO4(OH)2] octahedra, and statistically distributed SeVIO4 and SeIVO3 groups as the main building units.

(CuBr) 2P 8Se 3: preparation, structural, and vibrational spectroscopic characterization of an adduct of P 8Se 3 cages to Cu 2Br 2 rhombs

Orange–red (CuBr) 2P 8Se 3 was obtained from stoichiometric amounts of CuBr, P and Se by melting and subsequent annealing at 380 °C for 1 month. The crystal structure was determined from single crystal X-ray data. (CuBr) 2P 8Se 3 crystallizes in the orthorhombic system, space group Pbcm (No. 57), with a=8.761(1) A ̊ , b=11.957(1) A ̊ , c=13.858(1) A ̊ , V=1451.8(3) A ̊ 3, and Z=4. This compound consists of neutral P 8Se 3 cage molecules attached to Cu 2Br 2 rhombs. Vibrational spectroscopic data are reported for (CuBr) 2P 8Se 3 and for the homologous (CuI) 2P 8Se 3. The wavenumbers of the Cu–Br and Cu–I vibrational modes show an excellent correlation with the corresponding Cu–X bond lengths.

Organically templated zinc selenites: MIL-86 or [H 2N(CH 2) 2NH 2] 2·Zn 4(SeO 3) 4 and MIL-87 or [H 3N(CH 2) 3NH 3] 4·Zn 4(SeO 3) 8

Two new organically templated zinc selenites MIL-86 or [H 2N(CH 2) 2NH 2] 2·Zn 4(SeO 3) 4 and MIL-87 or [H 3N(CH 2) 3NH 3] 4·Zn 4(SeO 3) 8 have been prepared by the reaction of ZnO with SeO 2 under hydrothermal conditions in the presence of organic amines. Crystal data: MIL-86, monoclinic, space group P2 1/ n, a=6.7712(4) Å, b=9.4520(5) Å, c=8.0295(4) Å, β=113.601(1)°, V=470.91(4) Å 3; MIL-87, orthorhombic, space group Pbcm, a=8.8311(3) Å, b=7.8391(2) Å, c=16.2992(4) Å, V=1128.36(6) Å 3. MIL-86 combines the structural features of templated networks and coordination polymers. Its structure is built up from ZnO 3N tetrahedra and SeO 3 pseudo-pyramids as the polyhedral building units. The ZnN bond corresponds to a direct link between zinc and the ethylenediamine template. In the other hand, MIL-87 is built up from chains of vertex-linked ZnO 4 and SeO 3 building units crosslinked by 1,3-diammonium propane cations. These structures are understood by comparison with the already known organically templated zinc phosphites.

The crystal structures of kidwellite and ‘laubmannite’, two complex fibrous iron phosphates

AbstractThe previously unknown, complex crystal structures of two fibrous ferric iron phosphate minerals have been solved using single-crystal X-ray diffraction data. The structure of a slightly arsenatian kidwellite has been refined in space group P2/c (a = 20.117(4), b = 5.185(1), c = 13.978(3)Å, β = 107.07(3)°, V = 1393.8(5)Å3, Z = 2) to R1 = 5.21%; a revision of both space group symmetry and chemical formula is proposed. The idealized formula is Na(Fe3+,M)9+x(OH)11(H2O)3(PO4)6, where M = Fe3+, Cu2+ or other metal cation, and x ≈ 0.3. The structure of a slightly arsenatian ‘laubmannite’ (as defined by Moore, 1970) has been refined in space group Pbcm (a = 5.172(1), b = 13.999(3), c = 31.083(6)Å, V = 2250.5(8)Å3, Z = 4) to R1 = 3.14%. The revised, idealized formula is (Fe3+,Fe2+,M)8+x(OH,H2O)9(-H2O)2(PO4)5, where M = Fe3+, Cu2+ or other metal cation, and x ≈ 0.1. The framework structures of both minerals are similar. Dominant building units are dimers composed of face- and edge-sharing FeO6 octahedra. Whereas kidwellite contains an additional trimer built of three corner-sharing FeO6 octahedra, ‘laubmannite’ instead contains a dimer built of two corner-sharing FeO6 octahedra. Kidwellite contains only trivalent iron, while one of the Fe sites in ‘laubmannite’ is occupied by a mixture of Fe3+ and Fe2+ in a 1:1 ratio. In both structures, the FeO6-based building units are linked via corners to PO4 tetrahedra; the M sites are located in narrow channels and have very low occupancies (~2 to 7%) and strongly distorted [6]- or [5+1]-coordinations. Close structural relations between kidwellite and ‘laubmannite’, and other fibrous iron phosphates explain observations of epitaxial intergrowths of them.

Electronic structure of the uranium monogermanide UGe

The uranium monogermanide (UGe) crystallizes in the orthorhombic ThIn-type structure (Pbcm space group) in which the uranium and germanium atoms each occupy three crystallographic positions. The electronic structure of UGe compound has been studied using spin-polarized tight binding version of the linear muffin-tin orbital method in the atomic sphere approximation (TB LMTO ASA). The calculations showed that all three types of uranium atoms are magnetically ordered and their spin magnetic moments are equal to: −2.02,+1.88, and −0.24 μ B /atom.

Two dimorphs of 5-methylsulfanyl-1H-tetrazole.

5-Methylsulfanyl-1H-tetrazole, C(2)H(4)N(4)S, crystallizes in dimorphic forms; the alpha-form crystallizes at room temperature in the monoclinic crystal system, space group P2(1)/m, and the beta-form crystallizes by sublimation at 423 K in the orthorhombic crystal system, space group Pbcm. In both forms, the molecules occupy crystallographic mirror planes and are connected to one another via N-H...N hydrogen bonds, the amino H atoms being disordered. The two forms differ from one another in their packing; there are polar layers in the alpha-form and non-polar layers in the beta-form.

Synthesis, X-ray and optical characterizations of two new oxysulfides: LaInS 2O and La 5In 3S 9O 3

Two new compounds, LaInS 2O and La 5In 3S 9O 3 were synthesized in the La–In–S–O quaternary system. Both compounds crystallize in the orthorhombic system with lattice constants a=20.5421(6) Å, b=14.8490(4) Å, c=3.9829(1) Å for LaInS 2O, and a=4.1018(1) Å, b=26.833(1) Å, c=16.023(1) Å for La 5In 3S 9O 3. The structure of La 5In 3S 9O 3 was solved from single-crystal X-ray data, in the space group Pbcm, with Z=4; it is built from three-atom-thick (100) NaCl layers interleaved with fluorite-type ribbons, and is closely related to the structures of the known lanthanum and indium compounds La 10In 6S 17O 6 and La 4In 5S 13. Both compounds LaInS 2O and La 5In 3S 9O 3 exhibit a yellow color; measurement of their optical gaps gave 2.73 and 2.60 eV, respectively.

Structure and electrical resistivity of CeNiSb 3

The ternary antimonide CeNiSb 3 has been prepared from an Sb flux or from reaction of Ce, NiSb, and Sb above 1123 K. It crystallizes in the orthorhombic space group Pbcm with Z=12 and lattice parameters a=12.6340(7) Å, b=6.2037(3) Å, and c=18.3698(9) Å at 193 K. Its structure consists of buckled square nets of Sb atoms and layers of highly distorted edge- and face-sharing NiSb 6 octahedra. Located between the ∞ 2[Sb] and ∞ 2[NiSb 2] layers are the Ce atoms, in monocapped square antiprismatic coordination. There is an extensive network of Sb–Sb bonding with distances varying between 3.0 and 3.4 Å. The structure is related to that of RECrSb 3 but with a different stacking of the metal-centered octahedra. Resistivity measurements reveal a shallow minimum near 25 K that is suggestive of Kondo lattice behavior, followed by a sharp decrease below 6 K.

Synthesis and characterization of the Zintl phase Na 4Ba 3As 6 with isolated As 35− anions

The title compound was prepared by direct fusion of the corresponding elements at 800°C followed by slow cooling to room temperature. It crystallizes in the orthorhombic space group Pbcm (No. 57) with a=11.340(2), b=8.745(2), and c=14.920(2) Å, V=1479.8(5) Å 3, and Z=4. The structure is made of isolated V-shaped trimers As 3 5− and sodium and barium countercations. According to magnetic and resistivity measurements, Na 4Ba 3As 6 is a narrow-gap semiconductor, i.e. a closed-shell compound that fulfills the Zintl concept.

HRTEM study of orthorhombic zirconia in MgO-PSZ

High-resolution transmission electron microscopy (HRTEM) was used to study the phase of orthorhombic ZrO2formed in magnesia partially stabilized zirconia (MgO-PSZ) during HRTEM specimen preparation. Based on the three reported crystal structures of orthorhombic ZrO2, with the space groupsPbcm,Pbc21andPbca, here it is shown that orthorhombic ZrO2formed in MgO-PSZ has thePbcmstructure.

Die neuen Oxoarsenate(III) AAsO2 (A = Na, K, Rb) und Cs3As5O9. Darstellung, Kristallstrukturen und Raman-Spektren / The New Oxoarsenates(III) AAsO2 (A = Na, K, Rb) and Cs3As5O9. Synthesis, Crystal Structures and Raman Spectra

The new alkaline metal arsenates(III) were synthesized at a temperature of 500 °C via reaction of stoichiometric mixtures of the elemental alkali metals A and As2O3. In the crystal structures of the four title compounds, which have been determined by single crystal x-ray diffraction, the As(III) atoms are in ψ-tetrahedral coordination by oxygen exclusively. In NaAsO2 (orthorhombic, space group Pbcm, a = 1429.6(9), b = 677.3(3), c = 509.1(2) pm, Z = 8) and the compounds AAsO2 (A = K/Rb, orthorhombic, space group Pbcm, a = 715.1(2)/729.7(5), b =748.0(1)/775.2(5), c = 539.20(17)/541.1(3) pm, Z = 4) the AsO3 ψ-tetrahedra are condensed to form zig-zag chains [AsOO2/2]−. In the Cs phase Cs3As5O9 with a lower alkaline metal content (trigonal, space group P31m, a = 845.5(3), c = 602.6(2) pm, Z = 1) the two crystallographically independent ψ-tetrahedra AsO3/2 and AsOO2/2 are connected in a 2:3 ratio to give polar sheets [As5O9]3−.

The crystal structure of Er(HPO4)(NO3)·3 H2O: ab initio determination from X-ray powder diffraction data

Abstract The crystal structure of orthorhombic Er(HPO4)(NO3)·3 H2O has been determined from X-ray powder diffraction data. The unit cell dimensions are a = 10.1653(4) Å, b = 11.9178(5) Å, c = 6.8533(3) Å, V = 830.26(6), Z = 4. The space group is Pbcm (No. 57) or Pbc21 (No. 29). The structures were solved ab initio using EXPO program and refined by FULLPROF package. Because geometrical features of the two solutions are the same, the crystal structure has been described in the scope of the centrosymmetric Pbcm space group. Positions of the hydrogen atoms were not defined. The erbium atom is eight coordinated. It is surrounded by one nitrate anion, one water molecule and four phosphate groups. [ErO8] polyhedra are linked together through their edges forming infinite chains extended along the c axis. The chains are connected by phosphate groups to form layers palallel to the yz plane. Probable hydrogen bonds are discussed.

New Model for the Magnetic Structure of the Marokite‐Type Oxide CaMn2O4.

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