Alkalimetall-Oxosilicate A6[Si3O9] und A6[Si2O7] (A = Rb, Cs): Darstellung und Kristallstruktur/ The Alkaline Metal Oxo-Silicates A6[Si3O9] and A6[Si2O7] (A = Rb, Cs): Preparation and Crystal Structure

2001 ◽  
Vol 56 (4-5) ◽  
pp. 423-430 ◽  
Author(s):  
C. Hoch ◽  
C. Röhr

Abstract The title compounds were synthesized via reaction of quartz and AO2 (A = Rb, Cs) with the elemental alkali metals. Their crystal structures were determined on the basis of single crystal X-ray data. All compounds crystallize in the monoclinic system with space group P21/c and lattice constants a = 656.0(l)/684.7(3), b = 1329.7(3)/1375.7(4), c = 1647.6(3)/1703.6(8) pm, β = 107.78(3)/108.23(2)°, Z = 4 (A6[Si3O9], A = Rb/Cs) and a = 668.59(8)/711.4(1), b = 911.37(9)/952.1(2), c = 1121.09(9)/1192.7(7) pm, β = 125.52(9)/126.22(3)°, Z = 2(A6[Si2O7], A = Rb/Cs) respectively. The rubidium and cesium compounds are isotypic with the corresponding potassium silicates.

2003 ◽  
Vol 58 (7) ◽  
pp. 620-626 ◽  
Author(s):  
Franziska Emmerling ◽  
Caroline Röhr

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−.


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.


1989 ◽  
Vol 44 (8) ◽  
pp. 884-888 ◽  
Author(s):  
Dieter Fenske ◽  
Kurt Merzweiler

The chiral diphosphine 1 reacts with [(diolefin)Rh(THF)2]PF6 (diolefine: 1.5-cyclooctadiene, norbornadiene) to form the complexes 4 and 5. The structure of 4 was determined by single crystal X-ray analysis. 4 crystallizes in the monoclinic space group P21. The lattice constants (at 180 K) are: a = 974.0(6); b = 3889.2(29); c = 1309.4(5) pm; β = 105.25(4)°. The hydrogenation of methyl-α-acetamidocinnamate in the presence of 5 yields (R)-N-acetylphenylalanine methyl ester with 33% enantiomeric excess.


1997 ◽  
Vol 52 (1) ◽  
pp. 35-39 ◽  
Author(s):  
B. Wedel ◽  
Hk. Müller-Buschbaum

Pb3Fe2Te2O12 (I) and Pb2CoTeO6 (II) have been prepared by crystallization from melts. Single crystal X-ray investigations led to monoclinic (I) and tetragonal (II) symmetry, space groups C4s-Cc and D174h-14/mmm. Lattice constants I: a = 9.866(3), b = 15.332(4), c = 7.172(2) Å, β = 111.34(3)°, Z = 4. II: a = 5.661(5), c = 8.004(7) Å, Z = 2. (I) represents a new crystal structure, characterized by a network of octahedra occupied by Fe3+ and Te6+ in a disordered manner. The centres of negative charge of the lone pairs of Pb2+ in I are estimated by Coulomb term calculations. II belongs to the elpasolithe type


Author(s):  
Hidetomo Hongu ◽  
Akira Yoshiasa ◽  
Massimo Nespolo ◽  
Tsubasa Tobase ◽  
Makoto Tokuda ◽  
...  

Petzite, Ag3AuTe2, crystallizes in the space group I4132, which is a Sohncke type of space group where chiral crystal structures can occur. The structure refinement of petzite reported long ago [Frueh (1959). Am. Mineral. 44, 693–701] did not provide any information about the absolute structure. A new single-crystal X-ray diffraction refinement has now been performed on a sample from Lake View Mine, Golden Mile, Kalgoorlie, Australia, which has resulted in a reliable absolute structure [a Flack parameter of 0.05 (3)], although this corresponds to the opposite enantiomorph reported previously. The minimum Te–Te distance is 3.767 (3) Å, slightly shorter than the van der Waals bonding distance, which suggests a weak interaction between the two chalcogens. XANES spectra near the Au and Te L III edges suggest that the chemical-bonding character of Au in petzite is more metallic than in other gold minerals.


1977 ◽  
Vol 32 (6) ◽  
pp. 609-611 ◽  
Author(s):  
H.-R. Freund ◽  
Hk. Müller-Buschbaum

Single crystals of the compound Ho2Cu2O5 were obtained by melting the oxide mixture (2 CuO : 1 Ho2O3), using KF as a flux. The crystal structure was investigated by single crystal X-ray data (Space group C2v9-P 21 nb, lattice constants: a = 1247.8, b = 1081.3, c = 349.5 pm).


1986 ◽  
Vol 41 (4) ◽  
pp. 405-408 ◽  
Author(s):  
P. Böttcher ◽  
W. Flamm

Bis(tetramethylammonium)hexasulfide has been synthesized from tetramethylammoniumchlorid and Na2S5 in aqueous solution. Single crystal X-ray investigations revealed its structure. It crystallizes in the monoclinic system, space group P2/c, with two formula units in the cell. The cell constants are as follows: a = 7.353(1) Å , b - 5.712(2) Å, c = 20.318(4) Å, β = 99.3(1)°


Author(s):  
M. Akkurt ◽  
E. Sarıpınar ◽  
S. Öztürk ◽  
C. Yılmaz ◽  
H.-K. Fun

AbstractThe crystal structure of (4-methoxy-phenyl)-[4-(4-methoxy-phenyl)-1-(1-phenylethylideneamino)-2-thioxo-1,2-dihydro-pyrimidin-5-yl]-methanone, has beeen determined by single-crystal X-ray diffraction at 183(2) K. The compound crystallizes in the monoclinic system, space group


2012 ◽  
Vol 67 (5) ◽  
pp. 491-494 ◽  
Author(s):  
Dmitrijs Stepanovs ◽  
Anatoly Mishnev

Sildenafil citrate monohydrate, well known as Viagra®, is a drug for the treatment of erectile dysfunction. Here we present the X-ray crystal structure of the sildenafil base, C22H30N6O4S. The compound crystallizes in the monoclinic system, space group P21/c with the unit cell parameters a = 17:273(1), b=17:0710(8), c=8:3171(4) Å , b =99:326(2), Z = 4, V = 2420:0(3) Å3. A comparison with the known crystal structures of sildenafil citrate monohydrate and sildenafil saccharinate is also presented.


2007 ◽  
Vol 62 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Nachiappan Arumugam ◽  
Eva-Maria Peters ◽  
Martin Jansen

A new potassium molybdenum oxide, K6Mo10O33, was synthesized by solid state reaction from the appropriate quantities of pre-dried MoO3 and K2MoO4, fired at around 650 °C for 2 d. The structure has been solved by using single crystal X-ray diffraction. The compound adopts the space group P1, with the lattice constants a = 7.7100(5), b = 11.9659(8), c = 17.1321(12) A° , α = 86.42 (10), β = 77.18(10), γ = 74.14(10)°. The structure is built up of infinite chains of edge-sharing MoO6 octahedra and groups of four MoO6 octahedra forming Mo4O17 units. These sub-units are connected together by common vertices.


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