Absolute Crystal Structure Determination of Ergot Alkaloid - Dihydroergocristine Methanesulfonate Monohydrate

1995 ◽  
Vol 60 (8) ◽  
pp. 1333-1342 ◽  
Author(s):  
Jan Čejka ◽  
Jan Ondráček ◽  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Benzene Ring ◽  
Structure Determination ◽  
Ergot Alkaloid ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Space Group ◽  
R Value ◽  
Absolute Chirality

Dihydroergocristine methanesulfonate monohydrate crystallizes in orthorhorhombic space group P21212 (No. 18) with Z = 4, a = 12.736(2) Å, b = 39.089(5) Å, c = 7.130(1) Å, V = 3549.6(9) Å3. The indole moiety is nearly planar, both the ergoline ring C and the tripeptide ring F addopt an envelope E6 conformation. The ergoline ring D and the tripeptide ring E have a chair 1C4 conformation. The conformation of the ring G is between E1 and 5T1. The benzene ring H is planar. The structure was solved by direct methods and refined anisotropically to the final R value of 0.078 for 4219 statistically significant observed reflections [I o 1.96s(I)]. The absolute chirality was determined based on anomalous dispersion as: C4 (R), C8 (R), C6 (R), C17 (R), C25 (S), C24 (S), C19 (S).

scholarly journals The crystal structure of alstonite, BaCa(CO3)2: an extraordinary example of ‘hidden’ complex twinning in large single crystals

2020 ◽  
Vol 84 (5) ◽  
pp. 699-704
Author(s):  
Luca Bindi ◽  
Andrew C. Roberts ◽  
Cristian Biagioni
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Structure Determination ◽  
Unit Cell ◽  
Crystal Structure Determination ◽  
Unit Cell Parameters ◽  
Space Group ◽  
Cell Parameters ◽  
Structure Determinations

AbstractAlstonite, BaCa(CO3)2, is a mineral described almost two centuries ago. It is widespread in Nature and forms magnificent cm-sized crystals. Notwithstanding, its crystal structure was still unknown. Here, we report the crystal-structure determination of the mineral and discuss it in relationship to other polymorphs of BaCa(CO3)2. Alstonite is trigonal, space group P31m, with unit-cell parameters a = 17.4360(6), c = 6.1295(2) Å, V = 1613.80(9) Å3 and Z = 12. The crystal structure was solved and refined to R1 = 0.0727 on the basis of 4515 reflections with Fo > 4σ(Fo) and 195 refined parameters. Alstonite is formed by the alternation, along c, of Ba-dominant and Ca-dominant layers, separated by CO3 groups parallel to {0001}. The main take-home message is to show that not all structure determinations of minerals/compounds can be solved routinely. Some crystals, even large ones displaying excellent diffraction quality, can be twinned in complex ways, thus making their study a crystallographic challenge.

Neue Mangan(III)-Fluoridhydrate: Na[MnF4(H2O)2] und Na[MnF4(H2O)2] · H2O / New Fluoride Hydrates of Manganese(III): Na[MnF4(H2O)2] and Na[MnF4(H2O)2] · H2O

1990 ◽  
Vol 45 (5) ◽  
pp. 593-597 ◽  
Author(s):  
Werner Massa ◽  
Roland E. Schmidt
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Teller Effect ◽  
Crystal Structure Determination ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Jahn Teller ◽  
Jahn Teller Effect

Crystalline Na[MnF4(H2O)2] and Na[MnF4(H2O)2] · H2O have been precipitated from aqueous HF solution of MnO(OH) and NaF. The crystal structure determination of the trihydrate (space group C 2/c, Z = 8, α = 1638.1(2), b = 667.6(2), c = 1130.3(1) pm, β = 103.78(1)°; R/wR = 0.038/0.033 for 1696 independent reflections) showed the presence of isolated octahedral trans-[MnF4(H2O)2]- anions with an elongation of the H2O-Mn—OH2 axis due to the Jahn-Teller effect (Mn 1-O 224.6(2), Mn 1—F(mean) 183.7(1); Mn2-0 218.3(2), Mn2— F(mean) 184.7(2) pm). As a consequence, an unusual H-bond geometry is observed with a tetrahedral (instead of trigonal) environment of the coordinated O atoms. Na[MnF4(H2O)2] is monoclinic (space group C 2/m, C 2 or Cm, a = 816.6(4), b = 677.1(1), c = 496.8(2), β = 114.45(3)°), the crystals show twinning and 1-dimensional disorder.

scholarly journals A Brief History of Fourier Methods in Crystal-structure Determination

1985 ◽  
Vol 38 (3) ◽  
pp. 263 ◽  
Author(s):  
CA Beevers ◽  
H Lipson
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Heavy Atom ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Fourier Methods ◽  
Isomorphous Replacement ◽  
History Of

Fourier methods for the determination of crystal structures were first suggested by Bragg in 1929, and were then successfully used by Beevers and Lipson for determining the structure of CuS04.5H20 in 1934. It was necessary for methods of summation to be devised, and after some experimentation the Beevers-Lipson strips became established as the best device for the work. They enabled increasingly complicated structures to be derived, but ultimately more elaborate and automatic devices based on digital computers had to be introduced. At the same time, isomorphous-replacement, heavy-atom and direct methods were also developed and these have enabled structures of enormous complexity to be successfully determined.

Aluminiumbromid-Pyridiniumbromid-Verbindung: Kristallstruktur Kristallstrukturbestimmung von [Tris(pyridinium)bromid]bis(tetrabromoaluminat(III))/ Aluminiumbromide-Pyridiniumbromide Compounds: Crystal Structure Crystal Structure Determination of [Tris(pyridinium)bromide]bis(tetrabromoaluminate(III))

1988 ◽  
Vol 43 (8) ◽  
pp. 963-965 ◽  
Author(s):  
Harald Burger ◽  
Karl Hensen ◽  
Peter Pickel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Orthorhombic Space Group ◽  
Pyridinium Bromide ◽  
Space Group ◽  
Lattice Constants ◽  
Bromide Ion

AbstractThe compound [(PyH)3Br][AlBr4]2 is formed by melting stoichiometric amounts of AlBr/PyHBr in a ratio of 2:3. It crystallizes in the orthorhombic space group Pbca with lattice constants a = 1365.5(2), b = 1616.0(2), c = 2783.7(3) pm, Z = 8, Dc = 2.21 g/cm3. The structure was solved from 2810 diffractometer measured intensities (Cu -Kα radiation) and refined to Rw (F) = 0.071. The cation shows three pyridinium ions attached via N - H - Br hydrogen bonds to a central bromide ion. The N - Br distances are 321(1), 321(2) and 332(2) pm.

Powder diffraction data for copper hexafluorides: Ba2CuF6 and Pb2CuF6

1995 ◽  
Vol 10 (3) ◽  
pp. 221-222
Author(s):  
Maurice Samouël ◽  
Patrick Gredin ◽  
Ariel de Kozak
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray

Based on the crystal structure determination of orthorhombic Ba2CuF6 (space group Cmca), the previous X-ray powder patterns given for Ba2CuF6 (PDF 21-809) and Pb2CuF6 (PDF 22-654) are reindexed.

Crystal structure determination of 2-oxo-3-benzoyloxazolo[3,2-a]pyridine from X-ray powder data

2000 ◽  
Vol 215 (5) ◽  
Author(s):  
S.G. Zhukov ◽  
E.V. Babaev ◽  
V.V. Chernyshev ◽  
V. Rybakov ◽  
E.J. Sonneveld ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Crystal Symmetry ◽  
Crystal Structure Determination ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Mesoionic Compound

The crystal structure of the mesoionic compound 2-oxo-3-benzoyloxazolo[3,2-a]pyridine (CThe crystal symmetry is orthorhombic (space group Pna2

Synthese und Kristallstrukturbestimmung von Cs([18]Krone-6)Au · 8NH3/ Synthesis and Crystal Structure Determination of Cs([18]crown-6)Au· 8NH3

2006 ◽  
Vol 61 (10) ◽  
pp. 1205-1208 ◽  
Author(s):  
Hanne Nuss ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Determination ◽  
Liquid Ammonia ◽  
Crystal Structure Determination ◽  
Temperature Sensitive ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray

Cs([18]crown-6)Au ・ 8NH3 was synthesized from CsAu and [18]crown-6 in liquid ammonia. The extremely air- and temperature-sensitive colorless, block-shaped crystals were analyzed by single crystal X-ray diffractometry. The compound forms triclinic crystals of space group P1 (no. 1) with a = 8.765(2), b = 11.186(2), c = 13.997(3) Å , α = 86.180(6), β = 89.669(6), γ = 83.774(6)°, V = 1361.2(4) Å3. The crystal structure consists of ammonia nets extending perpendicular to [110] in which the Cs([18]crown-6) fragments and the auride anions are embedded

Synthesis, Properties and Crystal Structure Determination of a Perchloroheptafulvalene Isomer

1985 ◽  
Vol 38 (3) ◽  
pp. 383 ◽  
Author(s):  
HM Hugel ◽  
E Horn ◽  
MR Snow
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Structure Analysis ◽  
Lithium Chloride ◽  
Structure Determination ◽  
Full Matrix ◽  
Space Group ◽  
Synthesis Properties ◽  
R Value

Crystals of the syn-perchloroheptafulvalene isomer, C14Cl12, crystallize in the space group C2/c with a 12.376(6), b 10.980(4), c 15.242(4)Ǻ and β 100.54(3)°. The structure analysis of the isomer indicates molecular packing disorder into two orientations about the centre of symmetry. In the final full-matrix least-squares refinement the conventional R value converged at 0.042. Formation of the syn isomer is most likely to proceed through the perchloroheptatrienyl anion which can dimerize and form syn-perchloroheptafulvalene by cis elimination of lithium chloride.

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