Molecular and crystalline structure of cycloheptanespiro-3′(4′H)-6′,7′,8′,9′-tetrahydrocyclohexa[b][1,4]thiazole-2′(5′H)-thione from powder synchrotron X-ray diffraction data

2008 ◽  
Vol 64 (2) ◽  
pp. 217-222 ◽  
Author(s):  
Edward E. Avila ◽  
Asiloé J. Mora ◽  
Gerzon E. Delgado ◽  
Ricardo R. Contreras ◽  
Andrew N. Fitch ◽  
...  
Keyword(s):  
Crystalline Structure ◽  
Diffraction Data ◽  
Structural Modification ◽  
Rietveld Method ◽  
Theoretical Calculations ◽  
Tetrahedral Site ◽  
Direct Methods ◽  
X Ray Diffraction ◽  
Molecular Conformations ◽  
X Ray

A series of bidentate nitrogen–sulfur pro-ligands has been designed and synthesized with the purpose of introducing a structural modification that favours the tetrahedral site distortions of metalloprotein systems with metallic centers surrounded by ligands containing two N atoms and two S atoms as donor groups. Some of these new pro-ligands were obtained only as powders. Here we present the molecular and crystalline structure of cycloheptanespiro-3′(4′H)-6′,7′,8′,9′-tetrahydrocyclohexa[b][1,4]thiazole-2′(5′H)-thione (I) solved and refined from powder synchrotron X-ray diffraction data. Two independent molecules comprising a total of 36 non-H atoms were obtained from the direct-methods solution and refined against the powder X-ray diffraction data using the Rietveld method. The molecular conformations of the heterocyclic benzothiazine ring, the fused heptenyl ring and the heptanyl spiro ring are thoroughly discussed and compared with VASP theoretical calculations and other related structures. The packing of molecules in (I) is based on hydrogen bonds of the type N—H...S and hydrophobic C—H interactions.

Crystal structure of BaBi2Ta2O9

2000 ◽  
Vol 15 (2) ◽  
pp. 134-138 ◽  
Author(s):  
Carlos O. Paiva-Santos ◽  
Talita Mazon ◽  
Maria A. Zaghete ◽  
André L. Campos ◽  
J. A. Varela ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Standard Deviation ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Direct Methods ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Interatomic Distances ◽  
X Ray

The crystal structure of the Aurivillius compound Bi2BaTa2O9 prepared via the chemical route was determined by direct methods using EXPO97, and refined using the Rietveld method with conventional X-ray diffraction data. The structure was found to be tetragonal (space group I4/mmm, number 139) and Z=2, isomorphic of the Bi2BaNb2O9 reported by Blake and co-workers in the literature (1997). Two refinements were performed using the two asymmetry functions of DBWS-9807 (release 20/May/99). The unit cell for each case are: a=3.932 22(6) Å, c=25.5053(6) Å (RA) and a=3.932 50(7) Å, c=25.5069(6) Å (RCF). The differences for atom positions, interatomic distances and angles are in the range of one standard deviation. Final agreements factors are: Rwp=7.97%, S=1.84, RBragg=4.28%(RA), Rwp=7.98%, S=1.84, RBragg=4.30%(RCF). The occupancies of Ba and Bi in site 2b were refined but constrained to have their summation equal to 1.00. The same constraints were applied to the Ba and Bi of the 4e site. The results show that on site 2b there are 70% of Ba and 30% of Bi and on the site 4e there are 82% of Bi and 18% of Ba. The charge equilibrium is maintained for one standard deviation of the site occupancies.© 2000 International Centre for Diffraction Data.

Structure Refinements of the Layered Intergrowth Phases SbIIISbV x A 1−x TiO6 (x≃0, A = Ta, Nb) Using Synchrotron X-ray Powder Diffraction Data

1997 ◽  
Vol 53 (6) ◽  
pp. 861-869 ◽  
Author(s):  
C. D. Ling ◽  
J. G. Thompson ◽  
S. Schmid ◽  
D. J. Cookson ◽  
R. L. Withers
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Homologous Series ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray ◽  
The Family

The structures of the layered intergrowth phases SbIIISb^{\rm V}_xAl-xTiO6 (x \simeq 0, A = Ta, Nb) have been refined by the Rietveld method, using X-ray diffraction data obtained using a synchrotron source. The starting models for these structures were derived from those of Sb^{\rm III}_3Sb^{\rm V}_xA 3−xTiO14 (x = 1.26, A = Ta and x = 0.89, A = Nb), previously solved by single-crystal X-ray diffraction. There were no significant differences between the derived models and the final structures, validating the approach used to obtain the models and confirming that the n = 1 and n = 3 members of the family, Sb^{\rm III}_nSb^{\rm V}_xA n−xTiO4n+2 are part of a structurally homologous series.

Structure analysis of YBa2Cu3O7-δ thin films from X-ray diffraction data using Rietveld method

1994 ◽  
Vol 235-240 ◽  
pp. 633-634
Author(s):  
M. Pissas ◽  
E. Moraitakis ◽  
V. Phycharis ◽  
D. Niarchos
Keyword(s):  
Thin Films ◽  
Structure Analysis ◽  
Diffraction Data ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Structures of (S)-(−)-4-oxo-2-azetidinecarboxylic acid and 3-azetidinecarboxylic acid from powder synchrotron diffraction data

2006 ◽  
Vol 62 (4) ◽  
pp. 606-611 ◽  
Author(s):  
Asiloé J. Mora ◽  
Michela Brunelli ◽  
Andrew N. Fitch ◽  
Jonathan Wright ◽  
Maria E. Báez ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Direct Methods ◽  
X Ray Diffraction ◽  
Synchrotron Diffraction ◽  
X Ray ◽  
The Asymmetry

The crystal structures of the four-membered heterocycles (S)-(−)-4-oxo-2-azetidinecarboxylic acid (I) and 3-azetidinecarboxylic acid (II) were solved by direct methods using powder synchrotron X-ray diffraction data. The asymmetry of the oxoazetidine and azetidine rings is discussed, along with the hydrogen bonding.

Crystal structure of cis-Tetracarbonylbis(chloromercury)iron

1976 ◽  
Vol 29 (9) ◽  
pp. 1905 ◽  
Author(s):  
CL Raston ◽  
AH White ◽  
SB Wild
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Diffraction Data ◽  
Title Compound ◽  
Direct Methods ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Independent Molecules

The crystal structure of the title compound has been determined by direct methods from X-ray diffraction data and refined by least squares to a residual of 0.071 for 2647 'observed' reflections. Crystals are monoclinic, C2/c, a = 36.81(1), b = 11.181(2), c = 20.369(5) �, β = 95.28(3)�, Z = 32. There are four independent molecules in the asymmetric unit, all with the cis disposition of ligands (<Fe-Hg), 2.498 �; <Hg-Fe-Hg), 80.9�); in one of the molecules one of the carbonyl sites is occupied by a more substantial moiety, possibly a result of partial occupancy of HgCl as a result of disorder or decomposition.

Structure and conformational analysis of a bidentate pro-ligand, C21H34N2S2, from powder synchrotron diffraction data and solid-state DFTB calculations

2009 ◽  
Vol 65 (5) ◽  
pp. 639-646 ◽  
Author(s):  
Edward E. Ávila ◽  
Asiloé J. Mora ◽  
Gerzon E. Delgado ◽  
Ricardo R. Contreras ◽  
Luis Rincón ◽  
...  
Keyword(s):  
Solid State ◽  
Diffraction Data ◽  
Density Functional ◽  
Simulated Annealing Algorithm ◽  
Theoretical Calculations ◽  
Tight Binding ◽  
Van Der Waals Interactions ◽  
Am1 Calculations ◽  
X Ray Diffraction ◽  
X Ray

The molecular and crystalline structure of ethyl 1′,2′,3′,4′,4a′,5′,6′,7′-octahydrodispiro[cyclohexane-1,2′-quinazoline-4′,1′′-cyclohexane]-8′-carbodithioate (I) was solved and refined from powder synchrotron X-ray diffraction data. The initial model for the structural solution in direct space using the simulated annealing algorithm implemented in DASH [David et al. (2006). J. Appl. Cryst. 39, 910–915] was obtained performing a conformational study on the fused six-membered rings of the octahydroquinazoline system and the two spiran cyclohexane rings of (I). The best model was chosen using experimental evidence from 1H and 13C NMR [Contreras et al. (2001). J. Heterocycl. Chem. 38, 1223–1225] in combination with semi-empirical AM1 calculations. In the refined structure the two spiran rings have the chair conformation, while both of the fused rings in the octahydroquinazoline system have half-chair conformations compared with in-vacuum density-functional theory (DFT) B3LYP/6-311G*, DFTB (density-functional tight-binding) theoretical calculations in the solid state and other related structures from X-ray diffraction data. Compound (I) presents weak intramolecular hydrogen bonds of the type N—H...S and C—H...S, which produce delocalization of the electron density in the generated rings described by graph symbols S(6) and S(5). Packing of the molecules is dominated by van der Waals interactions.

X-ray Diffraction Study of the Crystal Structure of the Tl Ternary Chalcogenides Tl2x In2(1−x)Se2, x = 0.2, 0.3,...0.9

1998 ◽  
Vol 54 (4) ◽  
pp. 358-364 ◽  
Author(s):  
K. G. Hatzisymeon ◽  
S. C. Kokkou ◽  
A. N. Anagnostopoulos ◽  
P. I. Rentzeperis
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Rietveld Method ◽  
Direct Methods ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Volume Decrease

A series of thallium ternary chalcogenides with the composition Tl2x In2(1−x)Se2, x = 0.2, 0.3,...0.9, have been studied by X-ray powder and, for some of them, single-crystal diffraction. They are tetragonal, space group I4/mcm, Z = 4, and isostructural with the binary semiconductor TlSe. Their crystal structures have been solved by direct methods and refined by the Rietveld method to a precision which is satisfactorily comparable to single-crystal results. As x is changed from x = 0.2 to x = 0.9 the unit-cell parameters and volume decrease or increase following Kurnakov's law, which is valid for solid solutions. Refined positional parameters of Se, In—Se and Tl—Se bond lengths vary with x also according to the same law. The distribution of In and Tl cations in 4(a) and 4(b) sites depends on the stoichiometry x and the crystals are composed of [In3+Se2]_{\infty}^- chains along the c axis in which InSe4 tetrahedra share edges; the chains are interconnected with Tl+(In+) ions.

Crystalline structure of the TiO2 II high-pressure phase at 293, 223, and 133 K according to single-crystal x-ray diffraction data

2007 ◽  
Vol 52 (4) ◽  
pp. 195-199 ◽  
Author(s):  
S. K. Filatov ◽  
N. A. Bendeliani ◽  
B. Albert ◽  
J. Kopf ◽  
T. I. Dyuzheva ◽  
...  
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Crystalline Structure ◽  
Diffraction Data ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase

Crystal structure and powder X-ray diffraction data for new Tb3CuAl3Ge2 compound

2015 ◽  
Vol 30 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Chao Zeng ◽  
Guoqiang Lin ◽  
Weijing Zeng ◽  
Wei He
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Unit Cell ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Quaternary Compound ◽  
Space Group ◽  
X Ray

The crystal structure of new Tb3CuAl3Ge2 quaternary compound was studied by the Rietveld method from powder X-ray diffraction (XRD) data. The Tb3CuAl3Ge2 compound crystallized in the hexagonal Y3NiAl3Ge2-type structure with space group P-62m (no. 189) and lattice parameters a = 7.0041(2) Å, c = 4.1775(1) Å, V = 177.48 Å3. There is only one formula in each unit cell, Z = 1, and the density of Tb3CuAl3Ge2 is ρx = 7.1696 g cm−3. The reliability factors characterizing the Rietveld refinement results are Rp = 6.43%, Rwp = 8.65%, RB = 4.81%, and RF = 4.09%, respectively. The powder XRD data of Tb3CuAl3Ge2 were presented and the reliability of indexation is F30 = 120.9(0.0073, 34).

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