An X-ray and conformational study of 5,7-dihydro-1,11-dimethyl-6H-dibenzo[a,c]cyclohepten-6-one and its methyl derivatives

1993 ◽  
Vol 71 (5) ◽  
pp. 685-694 ◽  
Author(s):  
Robert R. Fraser ◽  
Corinne Bensimon ◽  
Fanzuo Kong ◽  
Xinfu Wu
Keyword(s):  
Minimum Energy ◽  
Membered Ring ◽  
Torsional Angle ◽  
Methyl Derivative ◽  
Molecular Mechanics Calculations ◽  
X Ray ◽  
Axial Conformer ◽  
Methyl Derivatives ◽  
Symmetric Structures ◽  
Van Der Waals Radii

The crystal structures for the title compound 1 and its α-methyl derivatives 2–4 have been determined. Molecular mechanics calculations of the conformation of minimum energy for 1, 3, and 4 correspond closely to the symmetric structures observed in the crystal. For 2, rotation at the CO—CH2 bond by 24° produced an asymmetric conformation matching that seen in the solid state. The calculated changes in energy as a function of the torsional angle for 1 and 2 were compared with those for cyclohexanone and the axial conformer of the α-methyl derivative. The energy requirements for conformational change in the seven-membered ring were significantly greater than for the cyclohexane analogue. The calculated energy differences between diastereomeric methyl derivatives 2–4, 6, and 7 were in agreement with epimerization experiments. The distance of closest approach observed between a proton of the axial methyls of 2 and 3 and the distal benzene ring is smaller than expected on the basis of van der Waals' radii.

An X-ray and conformational study of the α-chloro derivatives of 5,7-dihydro-1,11-dimethyl-6H-dibenzo[a,c]cyclohepten-6-one

1994 ◽  
Vol 72 (6) ◽  
pp. 1481-1488
Author(s):  
Robert R. Fraser ◽  
Corinne Bensimon ◽  
Neil C. Faibish ◽  
Fanzuo Kong
Keyword(s):  
Molecular Mechanics ◽  
Benzene Ring ◽  
Membered Ring ◽  
Single Atom ◽  
Conformational Study ◽  
Molecular Mechanics Calculations ◽  
X Ray ◽  
Chloro Derivatives ◽  
Torsional Angles ◽  
Derivatives Of

The crystal structures for four α-chloro derivatives 2–5 of the titled ketone 1 have been determined, confirming their earlier assignments of stereochemistry. Variations in the conformations of 2–5 suggested some flexibility in the central seven-membered ring. Molecular mechanics calculations of the changes in energy as a function of the internal torsional angles at the carbonyl of these chloro derivatives indicated the ring flexibility to be comparable to that of cyclohexanone. In the three compounds containing an axial chlorine the distance between the chlorine atom and two of the carbon atoms of the more remote benzene ring was 3.2 ± 0.1 Å, suggesting the value for the thickness of a benzene ring may be significantly smaller than the accepted value when it is interacting with a single atom.

The crystal structure of a chiral m-cyclophane

1985 ◽  
Vol 63 (12) ◽  
pp. 3298-3304 ◽  
Author(s):  
T. H. Chan ◽  
G. J. Kang ◽  
F. Belanger-Gariepy ◽  
F. Brisse ◽  
K. Steliou
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Molecular Mechanics ◽  
Absolute Configuration ◽  
Direct Methods ◽  
Membered Ring ◽  
Molecular Mechanics Calculations ◽  
Orthorhombic System ◽  
X Ray ◽  
System A

The crystal structure of a chiral m-cyclophane, the α-isomer of (S)-α-methoxy-α-(trifluoromethyl)phenylacetate ester of 13-(methoxycarbonyl)-14-hydroxy-17-methyl-[11]-m-cyclophane (C30H37O5F3, FW = 534.62) has been solved by direct methods and refined by a least-squares procedure to a final R = 0.048 for 2756 independent reflections. The crystals belong to the orthorhombic system, a = 10.8077(13), b = 13.676(3), c = 19.060(4) Å, V = 2817.2 Å3, Z = 4, and the space group is P212121. The absolute configuration of the chiral plane, using the S-configuration of the α-methoxy-α-(trifluoromethyl)phenylacetate ester as reference, is found to be S, in agreement with the X-ray result. The 14-membered ring has the slightly distorted rectangular conformation that has been described by Dale as the rectangular diamond-lattice conformation [3434]. The distortions, also observed in similar 14-membered rings, have been successfully approximated by molecular mechanics calculations.

Crystal structure of ziprasidone hydrochloride monohydrate, C21H22Cl2N4OS(H2O)

2015 ◽  
Vol 30 (3) ◽  
pp. 192-198
Author(s):  
James A. Kaduk ◽  
Kai Zhong ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Powder Diffraction ◽  
Density Functional ◽  
Minimum Energy ◽  
Strong Hydrogen Bond ◽  
Powder Diffraction File ◽  
X Ray ◽  
Hydrochloride Monohydrate ◽  
Positively Charged

The crystal structure of ziprasidone hydrochloride monohydrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Ziprasidone hydrochloride monohydrate crystallizes in space group P-1 (#2) with a = 7.250 10(3), b = 10.986 66(8), c = 14.071 87(14) Å, α = 83.4310(4), β = 80.5931(6), γ = 87.1437(6)°, V = 1098.00(1) Å3, and Z = 2. The ziprasidone conformation in the solid state is very close to the minimum energy conformation. The positively-charged nitrogen in the ziprasidone makes a strong hydrogen bond with the chloride anion. The water molecule makes two weaker bonds to the chloride, and acts as an acceptor in an N–H⋯O hydrogen bond. The powder pattern is included in the Powder Diffraction File™ as entry 00-064-1492.

Synthesis, characterization and X-ray studies of new chiral five-six-membered ring, [4.3.0] heterobicyclic system of monomeric boronates

2011 ◽  
Vol 696 (11-12) ◽  
pp. 2420-2428 ◽  
Author(s):  
José María Rivera ◽  
Susana Rincón ◽  
Norberto Farfán ◽  
Rosa Santillan
Keyword(s):  
Membered Ring ◽  
X Ray

Bestimmung von innermolekularen Torsionswinkeln aus Hyperfeinstruktur-Aufspaltungen und g-Faktoren

1965 ◽  
Vol 20 (9) ◽  
pp. 1117-1121 ◽  
Author(s):  
K. Möbius
Keyword(s):  
Electron Diffraction ◽  
Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbons ◽  
Small Amplitude ◽  
Membered Ring ◽  
Radical Ions ◽  
Hydrogen Atoms ◽  
Stereochemical Structure ◽  
X Ray ◽  
Phenyl Rings

The stereochemical structure of aromatic hydrocarbons in solution being overcrowded with hydrogen atoms is not known with certainty, because the conventional X-ray and electron diffraction methods are suitable only for samples in the crystalline and vapor phase. Using EPR spectroscopy for the aromatic hydrocarbon radicals biphenyl (—), phenanthrene (—) and pentaphenylcyclopentadienyl (PPCPD) innermolecular twist and bond angles could be determined by means of hfssplittings and g-factors. Stably solvated biphenyl radical ions are found to have twist angles of 38 ±2°; phenanthrene ions turn out to be planar but change their angles of hybridization at particular positions; in the PPCPD radical the phenyl rings oscillate with small amplitude around planes orthogonal to the five-membered ring.

X-Ray crystallographic study of a 1,3,2-dioxaphosphorinane dimer containing five-coordinated phosphorus in the 12-membered ring

1993 ◽  
Vol 4 (2-3) ◽  
pp. 271-278 ◽  
Author(s):  
Yande Huang ◽  
Alan E. Sopchik ◽  
Atta M. Arif ◽  
Wesley G. Bentrude
Keyword(s):  
Membered Ring ◽  
X Ray ◽  
Crystallographic Study

scholarly journals Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

2014 ◽  
Vol 10 ◽  
pp. 2021-2026 ◽  
Author(s):  
Henning Hopf ◽  
Swaminathan Vijay Narayanan ◽  
Peter G Jones
Keyword(s):  
Structural Analysis ◽  
Spectroscopic Data ◽  
Acid Treatment ◽  
Aldol Condensation ◽  
Membered Ring ◽  
X Ray

Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18–20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21–23. The structures of these elimination products are also deduced from X-ray and spectroscopic data. The sequence presented here constitutes the simplest route so far to cyclophanes carrying an annelated five-membered ring.

scholarly journals Silylated gallium and indium chalcogenide ring systems as potential precursors to ME (E=O, S) materials

2013 ◽  
Vol 11 (7) ◽  
pp. 1225-1238
Author(s):  
Iliana Medina-Ramírez ◽  
Cynthia Floyd ◽  
Joel Mague ◽  
Mark Fink
Keyword(s):  
Thermal Decomposition ◽  
Room Temperature ◽  
Membered Ring ◽  
Molecular Structures ◽  
Nmr Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
High Yields ◽  
Vt Nmr ◽  
State 1

AbstractThe reaction of R3M (M=Ga, In) with HESiR′3 (E=O, S; R′3=Ph3, iPr3, Et3, tBuMe2) leads to the formation of (Me2GaOSiPh3)2(1); (Me2GaOSitBuMe2)2(2); (Me2GaOSiEt3)2(3); (Me2InOSiPh3)2(4); (Me2InOSitBuMe2)2(5); (Me2InOSiEt3)2(6); (Me2GaSSiPh3)2(7); (Et2GaSSiPh3)2(8); (Me2GaSSiiPr3)2(9); (Et2GaSSiiPr3)2(10); (Me2InSSiPh3)3(11); (Me2InSSiiPr3)n(12), in high yields at room temperature. The compounds have been characterized by multinuclear NMR and in most cases by X-ray crystallography. The molecular structures of (1), (4), (7) and (8) have been determined. Compounds (3), (6) and (10) are liquids at room temperature. In the solid state, (1), (4), (7) and (9) are dimers with central core of the dimer being composed of a M2E2 four-membered ring. VT-NMR studies of (7) show facile redistribution between four- and six-membered rings in solution. The thermal decomposition of (1)–(12) was examined by TGA and range from 200 to 350°C. Bulk pyrolysis of (1) and (2) led to the formation of Ga2O3; (4) and (5) In metal; (7)–(10) GaS and (11)–(12) InS powders, respectively.

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