An I.C.T. Fortran program for least-squares refinement of crystal-structure cell dimensions

1967 ◽  
Vol 23 (6) ◽  
pp. 1113-1114 ◽  
Author(s):  
A. A. Cox ◽  
E. G. Steward
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Fortran Program ◽  
Cell Dimensions

scholarly journals The reaction of 3,5-diphenyl-1,2-dithiolium-4-olate with aniline: the crystal structure of 1-phenylimino-2-phenylamino-3-phenylindene

1987 ◽  
Vol 65 (12) ◽  
pp. 2830-2833 ◽  
Author(s):  
David M. McKinnon ◽  
Peter D. Clark ◽  
Robert O. Martin ◽  
Louis T. J. Delbaere ◽  
J. Wilson Quail
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

3,5-Diphenyl-1,2-dithiolium-4-olate (1) reacts with aniline to form 1-phenylimino-2-phenylamino-3-phenylindene (3a). Under suitable conditions, 6-phenylbenzo[b]indeno[1,2-e]-1,2-thiazine is also formed. These structures are confirmed by alternative syntheses. The molecular structure of 3a has been determined by single crystal X-ray diffraction. Compound 3a crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.777(3) Å, b = 6.130(3) Å, c = 31.327(3) Å, 3 = 99.59(1)°, and Z = 8. The structure was solved by direct methods and refined by least squares to a final R = 0.055. The molecular structure of 3a shows the three phenyl containing substituents to have the planes of their ring systems tilted between 40° and 60° from the plane of the indene system due to steric repulsions.

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.

scholarly journals Computer Programs for Standardless Quantitative Analysis of Minerals Using the Full Powder Diffraction Profile

1991 ◽  
Vol 6 (1) ◽  
pp. 2-9 ◽  
Author(s):  
J. C. Taylor
Keyword(s):  
Crystal Structure ◽  
Quantitative Analysis ◽  
Least Squares ◽  
Powder Diffraction ◽  
Profile Analysis ◽  
Unit Cell ◽  
Diffraction Profile ◽  
Pattern Processing ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractA Fortran 77 computer program has been developed for the quantitative analysis of minerals by multiphase profile analysis of the complete powder diffraction pattern. Featured are full-matrix least-squares refinement of 14 Rietveld “instrumental parameters” (phase scales, asymmetry, preferred orientations (March model), linewidths, instrument zero, lineshapes and unit cell dimensions), Brindley particle absorption contrast factors and amorphicity corrections. The program uses a crystal structure Databank, which contains information on absorption coefficients, unit cell data and crystal structures for some 90 common minerals. New minerals can be easily added. Structure parameters are also refinable by a profile decomposition method using a program called STRUCT. The sum of the calculated patterns, derived from the crystal structure data, is fitted to the observed pattern by a program called TRACSCAL which runs in singlepass multiphase mode and, after the above corrections have been applied, the weight percentages of the component phases are calculated from the Rietveld scaling factors.The program runs on an IBM-compatible AT computer with 640K of RAM, on an extended memory AT, or a mainframe system. Examples of its use are given with standard mixtures and naturally occurring specimens. On an AT computer with 20MHz clock speed a scaling run, including data input, reading of the pattern, processing of (hkl) files, calculation of the profile and one cycle of least squares fitting takes about 30 seconds for binary standard mixtures and about 2.5 minutes for a 7-phase natural bauxite pattern containing 320 independent (hkl) reflections.

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.

Powder diffraction analysis of substituted sulfonylurea

2002 ◽  
Vol 17 (1) ◽  
pp. 48-51 ◽  
Author(s):  
Yu PuLan ◽  
Ding Shuang ◽  
Qiao YuanYuan ◽  
Yao XinKan ◽  
Zhang HaiYue ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Least Squares ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Crystal Data ◽  
Cell Parameters ◽  
Cell Dimensions ◽  
Good Agreement

The crystal structure of a series of substituted sulfonylureas were studied in this paper by means of powder diffraction, and the cell dimensions of each compound were refined by a least squares analysis. The cell parameters were in good agreement with those obtained from single crystal data. © 2002 International Centre for Diffraction Data.

The crystal structure of benzenediazonium tetrafluoroborate, C6H5N2+•BF4−1

1982 ◽  
Vol 60 (22) ◽  
pp. 2852-2855 ◽  
Author(s):  
Miroslaw Cygler ◽  
Maria Przybylska ◽  
Richard MacLeod Elofson
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Benzene Ring ◽  
Positive Charge ◽  
Unit Cell ◽  
Full Matrix ◽  
Bond Lengths ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Close Contacts

Benzenediazonium tetrafluoroborate, C6H5N2+•BF4−, crystallizes in space group P21/a with unit cell dimensions a = 17.347(2), b = 8.396(1), c = 5.685(1) Å, β = 92.14(1)°, Z = 4. The structure was solved by direct phasing methods using the program SHELX 76. The parameters were refined by full-matrix least-squares to a final R = 0.063 for 1346 observed reflections. The bond lengths and angles agree very well with those of Rømming for benzenediazonium chloride. The C—N and N≡N bond lengths are 1.415(3) and 1.083(3) Å, respectively, and the bonds of the benzene ring do not show any significant differences as they vary from 1.371(5) to 1.383(4) Å. There are three [Formula: see text] close contacts of ≤ 2.84 Å and the positive charge appears to be shared between the nitrogen atoms.

scholarly journals Molekül- und Kristallstruktur von C7H7Mo(CO)2-SnCl3 / The Crystal Structure of C7H7Mo(CO)2-SnCl3

1975 ◽  
Vol 30 (1-2) ◽  
pp. 22-25 ◽  
Author(s):  
M. L. Ziegler ◽  
H.-E. Sasse ◽  
B. Nuber
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Title Compound ◽  
Three Dimensional ◽  
Unit Cell ◽  
Fourier Methods ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Group D

The structure of the title compound has been determined from three dimensional X-ray data by Patterson and Fourier methods. The crystals are orthorombic, with unit cell dimensions a = 1181,50 pm, b = 943,68 pm, c = 1181,50 pm, space group D2h16 and Z = 4. Least squares refinement, by use of 1540 independent reflections measured on a diffractometer has reached R = 5,9%.There are discrete C7H7Mo(CO)2 SnCl3 molecules, the molybdenum-tin bond has been dicussed together with the corresponding bonds in other C7H7Mo(CO)2 SnR3 compounds.

The crystal structure of the neuroleptic agent (±)-deoxybutaclamol and its significance for the topography of the central dopamine receptor

1980 ◽  
Vol 58 (14) ◽  
pp. 1444-1448 ◽  
Author(s):  
S. Fortier ◽  
M. Przybylska ◽  
L. G. Humber
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Binding Site ◽  
Dopamine Receptor ◽  
Direct Methods ◽  
Space Group ◽  
Proposed Model ◽  
Cell Dimensions ◽  
Pharmacological Studies ◽  
Neuroleptic Agent

(±)-Deoxybutaclamol, C25H31N, crystallizes in space group P21/a with cell dimensions: a = 16.626(3), b = 10.646(2), c = 11.278(3) Å, β = 90.47(4)°. The structure was solved by direct methods using the QTAN program. The coordinates were refined by block-diagonal least-squares calculations to R = 0.052 for 3147 observed reflections.The structure of (±)-deoxybutaclamol was found to be very similar to that of equipotent (±)-butaclamol and is in agreement with that assigned on the basis of chemical, spectral, crystallographic, and pharmacological studies. This confirmation validates the coordinates of a lipophilic accessory binding site in a proposed model of the central dopamine receptor.

Darstellung und Röntgenstrukturanalyse von (CH3)3C-C7H7Mo(CO)3 (1-6- η-7-tert-Butyl-cycloheptatrien)(tricarbonyl)molybdän(0) / Synthesis and Crystal Structure of (CH3)3C-C7H7Mo(CO)3 (1-6-η-7-tert-Butyl-cycloheptatriene)(tricarbonyl)molybdenum(0)

1975 ◽  
Vol 30 (9-10) ◽  
pp. 699-709 ◽  
Author(s):  
Peter O. Tremmel ◽  
Klaus Weidenhammer ◽  
Henning Wienand ◽  
Manfred L. Ziegler
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Title Compound ◽  
Three Dimensional ◽  
Synthesis And Crystal Structure ◽  
Fourier Methods ◽  
X Ray ◽  
Tert Butyl ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The title compound has been synthesized by three different methods and its structure determined from three dimensional X-ray data by Patterson and Fourier methods. The crystals are triclinic with unit cell dimensions a = 1022.60 ± 0.07 pm, b = 638.69 ± 0.27 pm, c = 1478.00 ± 0.19 pm, α = 78.48 ±0.02°, β = 131.049 ± 0.008°, γ = 87.16 ± 0.03 °, space group Ci1—PT and Z = 2. Least squares refinement by use of 2160 independent reflections measured on a diffractometer has reached R = 5.4%.There are discrete (CH3)3C—C7H7Mo(CO)3 molecules, the central molybdenum atom is octahedrally coordinated.

The Crystal Structure of a Thiathiophthen Nitrogen Isostere, 3,5-Epidithio-2,5-diphenyl-2,4-pentadienylidene-3-aminoquinoline

1971 ◽  
Vol 49 (2) ◽  
pp. 167-172 ◽  
Author(s):  
F. Leung ◽  
S. C. Nyburg
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
X Ray ◽  
Bond Lengths ◽  
Triclinic System ◽  
R Factor ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of a thiathiophthen nitrogen isostere (7) has been solved by X-ray analysis. The crystal belongs to the triclinic system with unit cell dimensions: a = 11.275(11), b = 9.558(10), c = 10.797(10) Å, α = 92.50(10), β = 116.98(10), γ = 92.61(10)°. There are two molecules per unit cell, space group [Formula: see text]. The data were collected by diffractometer with CuKα radiation. The structure was solved by symbolic addition procedures, and fully refined anisotropically using full-matrix least squares to an R factor of 6.3%.The S—S and S—N bond lengths were found to be 2.364 and 1.887 Å, respectively. This reveals the partial bonding character between S … S … N atoms.

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