The crystal structure of the trimethylsilyl derivative of the seven-membered ring silicate anion – [(CH3)3Si]14[Si7O21]

1993 ◽  
Vol 203 (1) ◽  
Author(s):  
Yu. I. Smolin ◽  
Yu. F. Shepelev ◽  
A. S. Ershov ◽  
D. Hoebbel
Keyword(s):  
Crystal Structure ◽  
Silicic Acid ◽  
Acid Ester ◽  
Direct Methods ◽  
Membered Ring ◽  
Trimethylsilyl Derivative ◽  
Silicate Anion

AbstractThe structure of trimethylsilyl cyclohepta silicic acid ester has been determined by direct methods. [(CH

The Crystal Structure of benzoyl – histidine monohydrate

1994 ◽  
Vol 209 (10) ◽  
Author(s):  
R. Fröhlich ◽  
R. K. Arni ◽  
A. Bozopoulos ◽  
C. A. Kavounis
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Tautomeric Form ◽  
Direct Methods ◽  
Membered Ring ◽  
Hydrogen Bridge ◽  
Reliability Factor ◽  
Full Matrix ◽  
Benzoyl Group ◽  
Expected Values

AbstractThe crystal structure of benzoyl-histidine monohydrate (BYLH hereafter), CThe structure was solved with direct methods. All positional and anisotropic thermal parameters were refined by full-matrix least-squares calculations. The final reliability factor wasThe compound consists of a histidine molecule bound to a benzoyl group. There is also a cocrystallized water molecule stabilized through a hydrogen bridge.The 5-membered ring of the histidine has its tautomeric form, after the transfer of the H atom from the NAll angle values and bond distances agree very well with the expected values in the literature.

The methylgallium-2-carboxylatobenzimidazolato hexamer, [MeGa·C8H4N2O2]6·C6H6·(Me2C6H4)2; synthesis and X-ray crystal structure

1999 ◽  
Vol 77 (4) ◽  
pp. 434-438 ◽  
Author(s):  
Steven J Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Room Temperature ◽  
Direct Methods ◽  
Membered Ring ◽  
Coordination Geometry ◽  
Temperature Reaction ◽  
Full Matrix ◽  
X Ray ◽  
Solvent Molecules

The room-temperature reaction of Me3Ga with benzimidazole 2-carboxylic acid in xylene solvent has yielded a novel crystalline hexameric gallium compound with "MeGa" moieties bridged by the doubly depronotated ligand precursor. Crystals of [MeGa(4,5-benzimidazolato-2-carboxylato)]6·(C6H6)·(m-Me2C6H4)2 are monoclinic, a = 18.091(2), b = 17.094(2), c = 13.2215(5) Å, Z = 2, space group C2/m. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R (F, I [Formula: see text] 3σ(I)) = 0.064 (Rw (F2, all data) = 0.134). The hexameric Ga complex contains a six-membered ring of Ga atoms, bridged by the benzimidazolate ligands with the benzo rings projecting alternately above and below the Ga plane, thus forming a ball-shaped molecule. The complex could have ideal D3d symmetry, but it contains an encapsulated molecule of benzene, which distorts the regularity of the Ga6 hexagon, and reduces the symmetry of the complex to the crystallographically observed C2h. The coordination geometry at each of the two independent GaO2N2C centres approximates a trigonal bipyramid, with a N2C trigonal plane, and the O atoms above and below; average dimensions are Ga-O = 2.176(2), Ga-N = 1.973(3), Ga-C = 1.927(5) Å, O-Ga-O = 165°. The unit cell also contains four m-xylene solvent molecules (outside the molecular cage).Key words: gallium, crystal structure, benzene intercalate, benzimidazolecarboxylic acid.

Crystal structure of 17,18,19-trisnorstemodan-3,13-dione

1984 ◽  
Vol 62 (9) ◽  
pp. 1828-1830 ◽  
Author(s):  
Stephen V. Evans ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Title Compound ◽  
Direct Methods ◽  
Membered Ring ◽  
Full Matrix ◽  
Bond Lengths ◽  
Compound C ◽  
Tetracyclic System ◽  
Atom Bond

Crystals of the title compound, C17H24O2, are monoclinic, P21/c, a = 10.395(2), b = 10.980(1), c = 13.181(3) Å, β = 113.55(1)°, Z = 4. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0.051 for 1622 reflections with I ≥ 3σ(I). The molecule contains a tetracyclic system of three six-membered rings and one five-membered ring; the structure exhibits disorder of one C atom. Bond lengths and angles are normal.

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe, IX [1]. Die Molekül- und Kristallstruktur von Tri-tert-butylcyclotriphosphanpentacarbonyl- chrom(O), [(t-BuP)3Cr(CO)5] / Structural Chemistry of Phosphorus-Containing Chains and Rings, IX [1]. The Molecular and Crystal Structure of Tri-tert-butylcydotriphosphane-pentacarbonyl-chromium (0), [(t-BuP)3Cr(CO)5]

1984 ◽  
Vol 39 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Karl-Friedrich Tebbe ◽  
Magda Fehér
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Direct Methods ◽  
Membered Ring ◽  
Free Molecule ◽  
Donor Ligand ◽  
Space Group ◽  
X Ray ◽  
Phosphorus Containing

The structure of [(t-BuP)3Cr(CO)5], C17CrH27O5P3, has been determined by single crystal X-ray techniques, solved by ‘direct methods', and refined to R = 0.048, wR = 0.050 for 3657 reflections by blocked least squares. The compound crystallizes in the space group P 21/c with a = 1664.9 pm, b = 916.5 pm , c = 3089.8 pm, β= 91.45° and Z = 8 formula units. The structure consists of two crystallographically independent but structurally nearly identical mononuclear [(t-BuP)3Cr(CO)5] complexes with the three-membered ring (t-BuP)3 as an unidentate σ-donor ligand. Compared to the free molecule (t-BuP)3 the cyclophosphane ligand is slightly distorted on account of its coordination to the Cr(CO)5-group.

Structural studies of organoboron compounds XL. 4,7-Dicyclohexyl-2,2,5,6-tetraphenyl- 1,3-dioxa-4-aza-7-azonia-2-boratacycloheptane

1990 ◽  
Vol 68 (10) ◽  
pp. 1797-1802 ◽  
Author(s):  
Henning Amt ◽  
Wolfgang Kliegel ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Least Squares ◽  
Direct Methods ◽  
Organoboron Compound ◽  
Chair Conformation ◽  
Membered Ring ◽  
Structural Studies ◽  
Full Matrix ◽  
Bond Lengths

The synthesis of 4,7-dicyclohexyl-2,2,5,6-tetraphenyl-1,3-dioxa-4-aza-7-azonia-2-boratacycloheptane is reported. Crystals of the compound are orthorhombic, a = 10.893(1), b = 28.072(1), c = 10.596(1) Å, Z = 4, space group P212121. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.036 and Rw = 0.043 for 2480 reflections with I ≥ 3σ(I). The molecule has a seven-membered chelate structure. The seven-membered ring, which has a twisted chair conformation, is stabilized by an intramolecular [Formula: see text] hydrogen bond. Bond lengths O—B = 1.468(4) and 1.554(4), C—B = 1.621(5) and 1.626(4) Å are consistent with moderately strong binding of the diphenylboron moiety by the O,O-chelating ligand. Keywords: crystal structure, organoboron compound, boron compound.

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 determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

scholarly journals The crystal structure of szenicsite, Cu3MoO4(OH)4

1998 ◽  
Vol 62 (04) ◽  
pp. 461-469 ◽  
Author(s):  
Peter C. Burns
Keyword(s):  
Crystal Structure ◽  
Goodness Of Fit ◽  
Direct Methods ◽  
Ligand Field ◽  
Area Detector ◽  
Vertex Sharing ◽  
Distorted Octahedral ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Least Squares Techniques

Abstract The crystal structure of szenicsite, Cu3MoO4(OH)4, orthorhombic, a = 8.5201(8), b = 12.545(1), c = 6.0794(6) Å, V = 649.8(2) Å3, space group Pnnm, Z = 4, has been solved by direct methods and refined by least-squares techniques to an agreement index (R) of 3.34% and a goodness-of-fit (S) of 1.11 for 686 unique observed [|F| ⩾ 4σF] reflections collected using graphite-monochromated Mo-Kα X-radiation and a CCD area detector. The structure contains three unique Cu2+ positions that are each coordinated by six anions in distorted octahedral arrangements; the distortions of the octahedra are due to the Jahn-Teller effect associated with a d 9 metal in an octahedral ligand-field. The single unique Mo6+ position is tetrahedrally coordinated by four O2− anions. The Cu2+ϕ6 (ϕ: unspecified ligand) octahedra share trans edges to form rutile-like chains, three of which join by the sharing of octahedral edges to form triple chains that are parallel to [001]. The MoO4 tetrahedra are linked to either side of the triple chain of Cu2+ϕ6 octahedra by the sharing of two vertices per tetrahedron, and the resulting chains are cross-linked through tetrahedral-octahedral vertex sharing to form a framework structure. The structure of szenicsite is closely related to that of antlerite, Cu3SO4(OH)4, which contains similar triple chains of edge-sharing Cu2+ϕ6 octahedra.

Molecular orbital structures of sulfones

1982 ◽  
Vol 60 (6) ◽  
pp. 730-734 ◽  
Author(s):  
Russell J. Boyd ◽  
Jeffrey P. Szabo
Keyword(s):  
Crystal Structure ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Geometry Optimization ◽  
Membered Ring ◽  
Molecular Orbital Calculations ◽  
Bond Lengths ◽  
Comparison With Experiment ◽  
The Difference

Abinitio molecular orbital calculations are reported for several cyclic and acyclic sulfones. The geometries of XSO2Y, where X, Y = H, F, or CH3 are optimized at the STO-3G* level. Similar calculations are reported for the smallest cyclic sulfone, thiirane-1,1 -dioxide, as well as the corresponding sulfoxide, thiirane-1-oxide, and the parent sulfide, thiirane. Where comparison with experiment is possible, the agreement is satisfactory. In order to consider the possibility of substantial differences between axial and equatorial S—O bonds in the gas phase, as observed in the crystal structure of 5H,8H-dibenzo[d,f][1,2]-dithiocin-1,1-dioxide, STO-3G* calculations are reported for a six-membered ring, thiane-1,1-dioxide, and a model eight-membered ring. Limited geometry optimization of the axial and equatorial S—O bonds in the chair conformations of the six- and eight-membered rings leads to bond lengths of 1.46 Å with the difference being less than 0.01 Å.

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