Tetranotriterpenoids and related compounds part 21.1 The crystal and molecular structure of a rearranged tetranortriterpenoid spiro-lactone from the bark of (meliaceae).

1979 ◽  
Vol 20 (11) ◽  
pp. 967-968 ◽  
Author(s):  
A. Forbes Cameron ◽  
Joseph D. Connolly ◽  
Abraham Maltz ◽  
David A.H. Taylor
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Related Compounds

Crystal and molecular structure of B,B-bis(p-tolyl)boroxazolidine and the orthorhombic form of B,B-diphenylboroxazolidine

1976 ◽  
Vol 54 (20) ◽  
pp. 3130-3141 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Statistical Analysis ◽  
Hydrogen Bonds ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Length Variation ◽  
Full Matrix ◽  
Space Group ◽  
Phenyl Rings ◽  
Related Compounds

Crystals of B,B-bis(p-tolyl)boroxazolidine, 1c, are trigonal, a = 25.1028(9), c = 12.4184(7) Å, Z = 18, space group [Formula: see text]. And crystals of B,B-diphenylboroxazolidine, 1a, are orthorhombic, a = 17.6420(4), b = 14.2527(3), c = 10.205(1) Å, Z = 8, space group Pbca. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to final R values of 0.057 and 0.040 for 2230 and 1828 reflections with I ≥ 3σ(I) respectively. Both molecules have structures similar to related compounds and feature intermolecular N—H … O hydrogen bonds (N … O = 2.982(2) for 1c and 2.896(2) Å for 1a). Bond lengths are: for 1c; O—C, 1.413(3), O—B, 1.478(3), N—C, 1.488(3), N—B, 1.657(3), C(sp3)—C(sp3), 1.501(4), B—C, 1.616(3) and 1.623(3), mean C—C(ar), 1.395, N—H, 0.93(2) and 0.94(2), mean C(sp3)—H, 1.00, and mean C(ar)—H, 1.00 Å; for 1a; O—C, 1.409(2), O—B, 1.476(2), N—C, 1.489(2), N—B, 1.655(2), C(sp3)—C(sp3), 1.507(3), B—C, 1.613(2) and 1.620(2), mean C—C(ar), 1.391, N—H, 0.93(2) and 0.92(2), mean C(sp3)—H, 1.00, and mean C(ar)—H, 0.98 Å. A statistical analysis of the phenyl C—C distances in compounds 1a, 1b, and 1c has provided an example of statistically significant substituent-induced bond length variation in the phenyl rings.

Crystal and Molecular Structure of 2,5-Bis(2′-hydroxyethylamino)-1,4-benzoquinone

1975 ◽  
Vol 53 (5) ◽  
pp. 777-783 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Full Matrix ◽  
Space Group ◽  
Compound C ◽  
Related Compounds ◽  
Centrosymmetric Molecule

Crystals of 2,5-bis(2′-hydroxyethylamino)-1,4-benzoquinone are monoclinic, a = 5.020(1), b = 19.238(3), c = 5.214(1) Å, β = 96.15(3)°, Z = 2, space group P21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.045 for 646 reflections with I ≥ 3σ(I). The benzoquinone ring in the centrosymmetric molecule is slightly, but significantly, nonplanar. Bond distances in the compound (C—C, 1.247 (2) and 1.410 (3), C—N, 1.332 (3) and 1.457 (3), C—C, 1.384–1.514 (3), N—H, 0.89 (3), O—H, 1.07 (5), and C—H, 0.95–1.09 (3) Å) are similar to those in related compounds. The structure features an extensive network of N—H … O (N … O = 2.639 (3) and 3.033 (2) Å) and O—H … O(O … O = 2.757 (3) Å ) hydrogen bonds.

Kristall- und Molekülstruktur des dimeren 1,2-Dioxyphenylen-siliciumdichlorids / Crystal and Molecular Structure of the Dimeric 1,2-Dioxyphenylene Silicondichloride

1989 ◽  
Vol 44 (12) ◽  
pp. 1550-1554
Author(s):  
Wolfgang Hönle ◽  
Urszula Dettlaff-Weglikowska ◽  
Leonhard Walz ◽  
Hans Georg von Schnering
Keyword(s):  
Molecular Structure ◽  
Viscous Liquid ◽  
Crystal And Molecular Structure ◽  
Chlorine Atoms ◽  
Space Group ◽  
Bond Angles ◽  
Bond Lengths ◽  
The Mean ◽  
Related Compounds

1,2-Dioxyphenylene silicondichloride is formed as a dimer from SiCl4 and catechol C6H4(OH)2 as the first reaction product. The compound melts at 413 K, yielding a viscous liquid which recrystallizes very slowly presumable under the formation of the monomer. 1,2-Dioxyphenylene silicondichloride crystallizes as a dimer in the space group P21/a (No. 14) with a = 1308.5(8) pm, b = 735.8(5) pm, c = 889.6(5) pm, β = 110.02(5)°, Z = 4 formula units. Silicon is tetrahedrally coordinated by two oxygen and two chlorine atoms with the mean bond lengths d̄(Si—O) = 160.7 pm and d̄(Si—Cl) = 200.7 pm. The bond angles at the Si atom range from 104.4 to 112.6° (endocyclic O—Si—O = 110.3°) and the bond angles ∢ (Si—O—C) are 131.4 and 135.9°, respectively. The results are discussed together with data of related compounds.

Structure and Conformation of Photosynthetic Pigments and Related Compounds, 8 [1]Molecular Structure of an Iron(III) Chlorophyll Derivative-Chloro(phytochlorinato methyl ester)iron(III)

1995 ◽  
Vol 50 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Mathias O. Senge ◽  
Karin Ruhlandt-Senge ◽  
Kevin M. Smith
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Axial Ligand ◽  
Monoclinic Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Chlorophyll Derivative ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Related Compounds

The crystal and molecular structure of chloro(methyl phytochlorinato)iron(III), 4, have been determined by single crystal X-ray crystallography to obtain further information on the conformation of metallochlorins related to chlorophyll. The compound crystallized with two independent molecules mainly distinguished by the orientation of the axial ligand. The macrocycles show significant deviations from planarity larger than those observed in corresponding magnesium(II) complexes. The overall type of distortion is similar to those found in chlorophyllides. Compound 4 crystallized in the monoclinic space group P21 (MoKa,λ = 0.71063 A) with unit cell dimensions a = 12.035(6) Å, b = 13.396(8) Å, c = 19.04(2), b = 97.51(2) Å, Z = 4, V = 3043(4) Å3. The structure was refined to an R-value of 0.075 on the basis of 3974 reflections with I > 3.0σ(Ι) (130 Κ).

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