Crystal structures of phenacylkojate (2-(hydroxymethyl)-5-phenacyloxy-4H-pyran-4-one) and its complex with sodium chloride: bis(phenacylkojate)sodium chloride

1976 ◽  
Vol 54 (17) ◽  
pp. 2723-2732 ◽  
Author(s):  
Simon E. V. Phillips ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Sodium Chloride ◽  
Potassium Iodide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Hydroxyl Groups ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Iodide Complex

The structures of the title compounds have been determined by three dimensional X-ray crystal structure analysis.Crystals of anhydrous phenacylkojate are monoclinic, space group P21/c, with unit cell dimensions a = 9.087(4), b = 11.764(3), c = 12.714(4) Å, β = 116.57(2)°, Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0.044 for 1225 independent diffractometer observations. The crystal structure is held together by hydrogen bonding between carbonyl and hydroxyl groups and [Formula: see text] interactions.Crystals of the sodium chloride complex are monoclinic, space group C2/c, with unit cell dimensions a = 11.3714(6), b = 15.796(1), c = 14.487(1) Å, β = 97.241(5)°, Z = 4. The structure was solved by heavy atom and Fourier methods and comparison with the previously determined structure of the potassium iodide complex. It was refined to R = 0.040 for 1670 independent diffractometer observations. The structure closely resembles that of the potassium iodide complex (P21/n), but in C2/c, the alkali metal ion being eight co-ordinate in each. Na+—O distances are in the range 2.558–2.674 Å and the [Formula: see text] hydrogen bonded distance is 3.266 Å.

Kristallstruktur von Bis(N.N′-bis(8-chinoyl)äthylendiaminato)nickel(II) / Crystal Structure of Bis(N,N′-bis(8-chinoyl)ethylenediaminato)nickel(II)

1977 ◽  
Vol 32 (2) ◽  
pp. 131-133 ◽  
Author(s):  
H. Endres ◽  
H. J. Keller ◽  
A. Poveda
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Least Squares ◽  
Title Compound ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Cell Dimensions ◽  
Planar Molecules ◽  
Unit Cell Dimensions

The title compound NiC20H16N4 crystallizes in the monoclinic space group Ρ21/a with unit cell dimensions a = 12.07(2) Å, b= 10.712(4) Å, c = 13.50(3) Å, β= 113.1(1)°. The structure was refined by a blockmatrix least squares procedure to R = 0.126, based on 1258 observed intensities. The planar molecules form centro-symmetric dimers in the solid state with interplane distances of 3.3 A.

Refinement of the structure of Mg2As2O7

1970 ◽  
Vol 48 (6) ◽  
pp. 890-894 ◽  
Author(s):  
C. Calvo ◽  
K. Neelakantan
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Central Oxygen ◽  
R Value ◽  
Unit Cell Dimensions

The crystal structure of Mg2As2O7 has been refined by full matrix least squares procedures using 587 observed reflections. The structure of Mg2As2O7 is of the thortveitite type, as reported by Łukaszewicz, with space group C2/m and unit cell dimensions a = 6.567(2) Å, b = 8.524(4) Å, c = 4.739(1) Å, β = 103.8(1)°, and Z = 2. The As—O—As group in the anion appears to be linear but the central oxygen atom undergoes considerable disorder in the plane perpendicular to this group. The AsO bond distances uncorrected for thermal motion are 1.67 Å for the As—O(—As) bond and 1.66 and 1.65 Å for the terminal As—O bonds. The final R value obtained is 0.088.

The Crystal Structure of Indium Monobromide

1950 ◽  
Vol 3 (4) ◽  
pp. 581 ◽  
Author(s):  
NC Stephenson ◽  
DP Mellor
Keyword(s):  
Crystal Structure ◽  
Layer Structure ◽  
Unit Cell ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of indium monobromide has been determined using powder and complete rotation photographs. The unit cell dimensions are ������������ a= 4.46�0.005 Ǻ������������ b=12.39�0.02 Ǻ ������������ c= 4 73�0.01 Ǻwith four molecules per cell. The space group is D172h:: -Cmcm. The structure is a layer structure isomorphous with that of thallium iodide TlI. Each indium has five bromine atoms arranged about it at the corners of a rectangular pyramid with one In-Br bond of 2.80 Ǻ and four In-Br bonds of 3.29 Ǻ. Indium atoms are similarly arranged about bromine atoms.

Crystal structure of Al5O3N3 (15R)

2017 ◽  
Vol 32 (S1) ◽  
pp. S2-S5 ◽  
Author(s):  
Jacek Podwórny ◽  
Alicja Pawełek ◽  
Jerzy Czechowski
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Structural Model ◽  
Stoichiometric Composition ◽  
Unit Cell ◽  
Second Phase ◽  
Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Having synthesised an AlON-bonded ceramic corundum material, Al5O3N3 (15R) polytype coexisting with α-Al2O3 was identified. The sample was prepared from an alumina-rich mixture of Al2O3 and AlN substrates and fired at 1650 °C in a nitrogen atmosphere. Using the X-ray external standard quantitative method, one of the reaction products, α-Al2O3, was quantified. From the remaining substrates the stoichiometric composition of the second phase was calculated. The applied method of crystal structure determination consisted of three stages. In the first stage, the Le Bail method of X-ray pattern decomposition was used for the extraction of Al5O3N3 (15R) diffraction lines from a two-phase diffractogram. The space group and unit-cell dimensions from the isostructural SiAl4O2N4 SiAlON phase, producing the same X-ray pattern, were used as input data. Next, the direct structure determination in real space was applied for initial structural model derivation, which was followed by Rietveld refinement. The solved crystal structure of Al5O3N3 (15R), except the stacking sequence, proved to be closely related to the structure of Al7O3N5 (21R) polytype. The Al5O3N3 (15R) is trigonal with space group R-3m, unit-cell dimensions a0 = 3.0128 Å, c0 = 41.8544 Å, and volume V = 329.00 Å3. The model of Al5O3N3 (15R) polytype structure has positional disordering in one of three (6c) Al sites, which leads to stacking faults in six tetrahedral layers. Every third tetrahedron from LR3 and LR4, LR8 and LR9, LR13 and LR14 layers is rotated by 180°.

Synthesis and crystal structure of Na3.5Cr1.5Co0.5(PO4)3 phosphate

2006 ◽  
Vol 21 (3) ◽  
pp. 210-213 ◽  
Author(s):  
Mohamed Chakir ◽  
Abdelaziz El Jazouli ◽  
Jean-Pierre Chaminade
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Hexagonal Unit Cell ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

A new Nasicon phosphates series [Na3+xCr2−xCox(PO4)3(0⩽x⩽1)] was synthesized by a coprecipitation method and structurally characterized by powder X-ray diffraction. The selected compound Na3.5Cr1.5Co0.5(PO4)3 (x=0.5) crystallizes in the R3c space group with the following hexagonal unit-cell dimensions: ah=8.7285(3) Å, ch=21.580(2) Å, V=1423.8(1) Å3, and Z=6. This three-dimensional framework is built of PO4 tetrahedra and Cr∕CoO6 octahedra sharing corners. Na atoms occupy totally M(1) sites and partially M(2) sites.

X-Ray structure of tris(acetonitrile)tricarbonylrhenium(I) tetrafluoroborate

1977 ◽  
Vol 55 (1) ◽  
pp. 111-114 ◽  
Author(s):  
Lillian Y. Y. Chan ◽  
E. E. Isaacs ◽  
W. A. G. Graham
Keyword(s):  
Least Squares ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
The Mean ◽  
Unit Cell Dimensions ◽  
Cell Data ◽  
Unit Cell Data

Reaction of [n-Bu4N]2[Re4(CO)16] with AgBF4 in acetonitrile affords the compound [(CH3CN)3Re(CO)3][BF4]. The latter crystallizes in monoclinic space group P21/c with unit cell dimensions a = 11.021(5) Å, b = 11.136(5) Å, c = 12.980(6) Å, β = 96.906(25)°, and four molecules per unit cell. Data were collected by counter methods and the structure was refined using least-squares procedures to give R = 0.041. The rhenium cation is approximately octahedrally coordinated by six facially arranged ligands. The mean rhenium–nitrogen distance is 2.13 Å, and the mean rhenium–nitrogen–carbon angle in the coordinated acetonitrile is 174.7°.

Le tétrabromomercurate(II) de monométhylammonium

1983 ◽  
Vol 16 (1) ◽  
pp. 142-143 ◽  
Author(s):  
A. Ben Salah
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Bis(monomethylammonium) tetrabromomercurate, (CH3NH3)2HgBr4, 2CH6N+.Hg2+.4Br−, is monoclinic, space group P21/c. Unit-cell dimensions are: a = 7.979(4), b = 13.351(4), c = 11.289(4) Å, β = 96.36(2)°, Z = 4, Dm = 3.25, Dx = 3.24 Mgm−3. The compound undergoes a phase transition at low temperature. The JCPDS Diffraction File No. of this compound is 33-1997.

scholarly journals Comparison of the C—H...O bonding in two crystalline phases of 1,4-dithiane 1,1,4,4-tetraoxide

2019 ◽  
Vol 75 (5) ◽  
pp. 576-579
Author(s):  
Richard L. Harlow ◽  
Allen G. Oliver ◽  
Jonathan M. Baker ◽  
William J. Marshall ◽  
Michael P. Sammes
Keyword(s):  
Hydrogen Bonds ◽  
Phase 1 ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Nmr Spectrum ◽  
Crystalline Phases ◽  
Space Group ◽  
H Nmr ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structures of two crystalline phases of 1,4-dithiane 1,1,4,4-tetraoxide, C4H8O4S2, have been determined in order to examine the nature of possible intermolecular hydrogen bonds. Phase 1 is monoclinic, space group C2/m, with unit-cell dimensions of a = 9.073 (8), b = 7.077 (6), c = 5.597 (5) Å and β = 105.89 (1)°. The molecule adopts 2/m symmetry and all of the molecules are related by translation and thus have the same orientation. Phase 2 is also monoclinic but in space group P21/n with unit-cell dimensions of a = 7.1305 (5), b = 5.7245 (4), c = 8.3760 (6) Å and β = 91.138 (2)°. In this phase, the molecule sits on an inversion center and the molecules within the unit cell adopt quite different orientations. In both phases, examination of the potential C—H...O hydrogen bonds around each of the independent oxygen atoms (one axial and the other equatorial) shows the general O...H patterns to be quite similar with each oxygen atom in contact with four neighboring H atoms, and each H atom contacting two neighboring O atoms. While none of the H...O contacts is particularly short (all are greater than 2.5 Å), each molecule has 32 such contacts that form an extensive intermolecular network. A 1H NMR spectrum of the compound dissolved in DMSO shows a singlet of 8H at δ 3.677 which indicates that the C—H bonds are only moderately polarized by the single adjacent –SO2– moiety: strongly polarized C—H bonds have δ values in the 5–6 range [Li & Sammes (1983). J. Chem. Soc. Perkin Trans. 1, pp. 1303–1309]. The phase 1 crystal studied was non-merohedrally twinned.

Structural parameters: Analysis of results

2010 ◽  
Author(s):  
Jenny Pickworth Glusker ◽  
Kenneth N. Trueblood
Keyword(s):  
Crystal Structure ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Molecular Geometry ◽  
Unit Cell ◽  
Space Group ◽  
Cell Dimensions ◽  
Information File ◽  
The Individual ◽  
Unit Cell Dimensions

The results of an X-ray structure analysis are coordinates of the individual, chemically identified atoms in each unit cell, the space group (which gives equivalent positions), and displacement parameters that may be interpreted as indicative of molecular motion and/or disorder. Such data obtained from crystal structure analyses may be incorporated into a CIF or mmCIF (Crystallographic Information File or Macromolecular Crystallographic Information File). These ensure that the results of crystal structure analyses are usefully archived. There are many checks that the crystallographer can make to ensure that the CIF or mmCIF file is correctly informative. For example, the automated validation program PLATON (Spek, 2003) checks that all data reported are up to the standards required for publication by the International Union of Crystallography. It does geometrical calculations on the structure, illustrates the results, finds if any symmetry has been missed, investigates any twinning, and checks if the structure has already been reported. We now review the ways in which these atomic parameters can be used to obtain a three-dimensional vision of the entire crystal structure. When molecules crystallize in an orthorhombic, tetragonal, or cubic unit cell it is reasonably easy to build a model using the unit-cell dimensions and fractional coordinates, because all the interaxial angles are 90◦. However, the situation is more complicated if the unit cell contains oblique axes and it is often simpler to convert the fractional crystal coordinates to orthogonal coordinates before calculating molecular geometry. The equations for doing this for bond lengths, interbond angles, and torsion angles are presented in Appendix 12. If the reader wishes to compute interatomic distances directly, this is also possible if one knows the cell dimensions (a, b, c, ∝ , β , γ ,), the fractional atomic coordinates (x, y, z for each atom), and the space group.

Refinement of the Crystal Structure of Synthetic Chervetite, Pb2V2O7

1973 ◽  
Vol 51 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Robert D. Shannon ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Unit Cell ◽  
Type Structure ◽  
Covalent Bonds ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The structure of synthetic chervetite has been refined by full matrix least-squares to a ωR = 0.029 using 1105 reflections. Unit cell dimensions are a = 13.3689(7), b = 7.1607(4), c = 7.1027(4) Å, β = 105935(5)°, and the space group is P21/a. The structure, originally solved by Kawahara, is a dichromate-type structure with a V2O74− group eclipsed to within 11 ± 5°. The Pb2+ ions are irregularly coordinated to 8 or 9 oxygens with distances from 2.40 to 3.20 Å. The distortion of the Pb–O distances is considerably greater than the corresponding distortions of the Sr–O distances in the similar β-Sr2V2O7 structure and is related to the tendency of Pb2+ to form directional covalent bonds. The V–O distances range from 1,665 to 1.720 Å for terminal oxygens and are 1.812 and 1.821 Å for the bridging oxygens. The V–O distances are consistent with the strengths of the Pb—O bonds.

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