The crystal structure of bicchulite, Ca2[Al2SiO6](OH)2

Author(s):  
Kurt Sahl ◽  
Niranjan Deb Chatterjee

AbstractThe crystal structure of synthetic bicchulite was determined with single-crystal x-ray methods (

1988 ◽  
Vol 43 (4) ◽  
pp. 497-498
Author(s):  
Franz A. Mautner ◽  
Harald Krischner ◽  
Christoph Kratky

Abstract The crystal structure of Rb2Ca(N3)4 · 4H2O has been determined by single crystal X-ray methods. The compound is isotypic with K2Ca(N3)4 · 4 H2O and crystallizes in the orthorhombic space group Ccca, Z = 4, a = 1949.1(12) pm, b = 1099.5(3) pm, c - 622.2(1) pm.


1971 ◽  
Vol 38 (295) ◽  
pp. 286-294 ◽  
Author(s):  
J. Pastor-Rodriguez ◽  
H. F. W. Taylor

SummaryThe crystal structure of coalingite (Mg10Fe2(OH)24(CO3)·2H2O) has been determined using single-crystal X-ray methods. The mineral is trigonal, with space group Rm, aH = 3·12, cH = 37·4 Å, Z = ½, and (0001) cleavage. The structure is of a layer type, and is based on a structural element about 12·5 Å thick in the c-direction and consisting of two brucite-like layers and one disordered layer containing carbonate ions and water molecules and resembling those in sjögrenite and pyroaurite. The unit cell comprises three of these structural elements stacked together in the c-direction. The Mg2+ and Fe3+ ions are randomly distributed among all the octahedral sites of the brucite-like layers. The structure closely resembles those of sjögrenite and pyroaurite, but has two brucite-like layers between each CO32−−H2O layer where these have one. There is a tendency to random interstratification, and the crystals appear to contain intergrown regions of brucite and of sjögrenite or pyroaurite. Coalingite-K probably has a similar structure, but with three brucite-like layers between each -H2O layer; its idealized formula is probably Mg16Fe2(OH)36(CO3).2H2O.


1989 ◽  
Vol 44 (8) ◽  
pp. 942-945 ◽  
Author(s):  
Wolfgang Schnick

Phosphorothionic triamide SP(NH2)3 is obtained by slow addition of SPCl3 dissolved in dry CH2Cl2 to a satured solution of NH3 in CH2Cl2 at —50°C. Ammonium chloride is removed from the resulting precipitate by treatment with HNEt2 followed by extraction with CH2Cl2. Coarse crystalline SP(NH2)3 is obtained after recrystallization from dry methanol. The crystal structure of SP(NH2)3 has been determined by single crystal X-ray methods (Pbca; a = 922.3(1), b = 953.8(1), c = 1058.4(2) pm, Z = 8). In the crystals the molecules show non-crystallographic point symmetry C8. The P—S bond (195.4(1) pm) is slightly longer than in SPCl3. From P—N bond lengths of about 166 pm a significant electrostatic strengthening of the P—N single bonds is assumed. Weak intermolecular hydrogen bonding interactions (N —H · · · N ≥ 329.5 pm; N — H · · · S ≥ 348.3 pm) are observed.Investigation of thermal properties shows a melting temperature of 115°C for SP(NH2)3. According to combined DTA/TG and MS investigations above this temperature the compound decomposes by evolution of H2S and NH3 to yield amorphous phosphorus(V)nitride.


1994 ◽  
Vol 49 (6) ◽  
pp. 721-728 ◽  
Author(s):  
Gerhard Cordier ◽  
Volker Müller

Na17Ga29ln12 (a = 2178.5(5) pm, Fd3m, Z = 8, R = 0.081) and K17In41 (a = 2424.1(5) pm, Fd3m, Z = 8, R = 0.060) have been prepared from the elements and characterized by single crystal X -ray methods. Na17Ga29ln12 is a ternary variant of K17In41. The crystal structure of Na17Ga29ln12 contains Ga12 icosahedra (In 12 icosahedra in K17In41) and truncated In12 tetrahedra which are four-capped and centred by additional Ga atoms (In atoms in K17In41). The packing of icosahedra and truncated tetrahedra leads to interpenetrating Samson polyhedra. The Ga12 icosahedra (In12 icosahedra in K17In41) take the Cu positions of the MgCu2 type, the In12 clusters take the positions of the Mg atoms of this structure type. The alkali atoms in Na17Ga29In12 and K17In41 occupy the deltahedral faces of the icosahedra and form pentagonal dodecahedra


1980 ◽  
Vol 35 (6) ◽  
pp. 672-675 ◽  
Author(s):  
Chr. L. Teske

Abstract Ba2ZnGe2S6O was prepared for the first time and the crystal structure determined by using single crystal X-ray methods. The space group is D32d-P4̄21m, tetragonal (No. 113). Lattice constants: a = 963.59 ± 0.22; c = 645.06 ± 0.25 pm. The tetrahedral framework structure is described and discussed. Zn is linked only to sulfur. The oxygen belongs to the coordination sphere of Ge and Ba.


1982 ◽  
Vol 37 (12) ◽  
pp. 1534-1539 ◽  
Author(s):  
D. Babel

The crystal structure of the cubic compound [N(CH3)4]2CsFe(CN)6 was determined by X-ray methods: a = 2527.4(6) pm, space group Fd3c, Z = 32, Rg = 0.028 (260 independent single crystal reflections). The resulting distances within the practically undistorted Fe (CN)63- - octahedron are Fe-C = 193.4(6) and C-N = 115.7(7) pm. Compared to the ideal elpasolite structure of space group Fm3m, Z = 4, the octahedra are rotated by 7.4° through their 3 axis. This is discussed as caused by steric requirements of the tetramethylammonium groups (N-C = 148.4(10) and 149.1(38) pm, resp.). Three quarters of them, of which also the hydrogen positions could be located, are well oriented. The remaining quarter shows orientational disorder to approach similar contact distances as the other N(CH3)4+ ion exhibits between the methyl groups and the nitrogen ends of the anions


1997 ◽  
Vol 52 (7) ◽  
pp. 819-822 ◽  
Author(s):  
Bernd Schwarze ◽  
Wolfgang Milius ◽  
Wolfgang Schnick

Abstract The chlorinated titanium amides [(Cl3Si)2N]2TiCl2 (1) and (Cl3Si)2NTiCl3 have been syn­thesized selectively from hexachlorodisilazane lithium and TiCl4. The crystal structure of 1 was determined by single crystal X-ray methods at room temperature (P212121, a = 1232.4(2), b = 1265.5(2), c -1469.1(2) pm, Z = 4). The central titanium atom of 1 is bound to two nitrogen atoms and two Cl atoms and is weakly coordinated further by two Cl atoms of the trichlorosilyl groups.


Author(s):  
H. Effenberger ◽  
K. Mereiter ◽  
J. Zemann

AbstractThe crystal structures of magnesite, calcite, rhodochrosite, siderite, smithonite and dolomite were refined by standard single crystal X-ray methods using diffraction data up to sin[unk]/


1993 ◽  
Vol 48 (5) ◽  
pp. 683-684 ◽  
Author(s):  
Wolfgang Hönle

The crystal structure of LiZnAs has been verified with single crystal X-ray methods. LiZnAs crystallizes in a filled-up zinc blende type of structure (F 43 m, a = 593.9(1) pm, As at site 4a (000); Zn at site 4d (3/4 3/4 3/4); Li at site 4 c (1/4 1/4 1/4); 25 hkl; R = 0.018). As is coordinated by 4 Li and 4 Zn atoms with identical distances of 257.2(1) pm. Li and Zn atoms are tetrahedrally coordinated by As. No indications for a disorder between Li and Zn have been found.


1987 ◽  
Vol 40 (9) ◽  
pp. 1609 ◽  
Author(s):  
AJ Canty ◽  
BW Skelton ◽  
AH White

Crystals of methyl[tetrakis(pyrazol-l-yl)borato-N,N']mercury(II) [MeHg(B(pz)4}] are triclinic, Pi, a 12.73(2), b 8.88(1), c 8.10(1) �, α 109.80(8), β 99.16(9), γ 103.05(10)�, Z 2. The structure, determined by single-crystal X-ray methods (R 0.12 for 1598 'observed' reflections), has molecules of MeHg(B(pz)4} with two pz groups coordinated to mercury, giving planar but irregular coordination. The more strongly bound group has Hg-N 2.07(4) A with C-Hg-N 169(2)�, and the other group has Hg-N 2.65(4)� with C-Hg-N 112(1)�.


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