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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 11 (1981), S. 33-42 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The previously reported IR study on 21 different 1-substituted 3-acylamino-2-pyrazolines assumed thecis configuration for the amide groups. In order to establish the configuration, X-ray structure determinations of two model compounds (1-phenyl-3-benzoylaminopyrazoline, monoclinic,a = 5.218,b = 8.830,c = 14.372 Å, β = 90.7 °,Z = 2, P2 1; 1-benzyl-3-acetaminopyrazoline, monoclinic,a = 9.529,b = 13.679,c = 18.112 Å, β = 96.7 °,Z = 8,P21/n) were performed. Both structures were solved by direct methods, and refined to a finalR = 0.075 for 710 andR = 0.122 for 2140 observed reflections. The configurations of the amide groups were found to betrans.
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  • 2
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of 2,4-dinitrophenyl phenylsulfide, C12H8N2O4S, has been determined by single crystal X-ray diffraction. The crystals are monoclinic, space groupP2 1/n, Z = 8, witha = 10.670(2),b = 8.381(4),c = 27.998(18) Å, and β = 100.44(4) °. There are two crystallographically independent molecules per asymmetric unit. All intensity measurements were made at room temperature on an Enraf-Nonius CAD-4 automatic diffractometer using monochromatized MoKα radiation. The structure was solved by direct methods and refined to a finalR value of 0.032. The two independent molecules have nearly identical geometries, with the most notable difference being the torsion angles involving the sulfur atoms. Thepara-nitro groups are more nearly in the planes of the central phenyl rings than are theortho-nitro groups although there may be nonbonded attractions between the latter. The two phenyls of each molecule are nearly at right angles to each other, as necessitated by steric forces involvingortho hydrogens. The characteristic distortions of the central phenyl rings caused by differing substituent electronegativities and degrees of conjugation are noted. The13C-NMR spectrum of the compound was assigned by comparison of calculated with observed chemical shift data. Calculated chemical shifts were obtained by incrementation of the chemical shifts of diphenylsulfide with standard nitro group additivities which were adjusted for the sulfur-nitro group interaction. Where necessary, assignments were confirmed with selective excitation spin-coupled subspectra. Solution behavior of the molecule was determined from spin-lattice (T 1) relaxation measurements which showed the unsubstituted ring to reorient anisotropically about the C(21)-C(24) bond axis while the substituted ring appears to be governed by the overall isotropic reorientation of the molecular framework, indicating that the sulfur-nitro group interaction restricts anisotropic reorientation about the C(11)-C(14) bond axis.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 11 (1981), S. 69-78 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
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  • 4
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reactions in THF or benzene between Cp2 M (HgX)2 ·x HgX 2 (M = Mo or W; O ⩽x ⩽ 1;X − = Cl−, Br−, I−, SCN−, OAc−) and sodium diethyl-dithiocarbamate $$\begin{gathered} Cp_2 M\left( {HgX} \right)_2 .xHgX_2 + \left( {2 + x} \right)Nadtc \rightleftharpoons Cp_2 M\left( {Hgdtc} \right)_2 \hfill \\ + xHg\left( {dtc} \right)_2 + \left( {2 + x} \right)NaX \hfill \\ \end{gathered} $$ as well as between Cp2 MH2 and mercury diethyldithiocarbamate $$x2Cp_2 MH_2 + 2Hg\left( {dtc} \right)_{2 - } Cp_2 M\left( {Hgdtc} \right)_2 + \left\{ {Cp_2 Mdtc} \right\}dtc + 2H_2 $$ give the compound Cp2 M(Hgdtc)2 (dtc is diethyldithiocarbamate anion). The structure of the molybdenum complex determined by the X-ray method (a = 12.776(4),b = 7.835(4),c = 27.397(7) Å β = 111.18(2) °; space groupC2/c (No. 15);Z = 4) consists of discrete molecules occupying special positions on two-fold axes. A short Mo-Hg distance of 2.643(8) Å and a rather long Hg-S one of 2.50(2) Å were found. The diethyldithiocarbamate anion behaves like a monodentate ligand. IR and1H,13C NMR results agree with the molecular structure determination and confirm a weak bond between mercury and dithiocarbamate and strong molybdenum-mercury bond. A considerable solvent effect (C6D6 vs. CDCl3 solutions) has been observed on the1H chemical shifts of both dtc and Cp ligands. The {Cp2Modtc}+ X − (X = dtc and PF6) complexes, although not obtained in a pure form, were included in the discussion of the spectroscopic features of those with theM-Hg bonds.
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  • 5
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure ofH 4a ,H 9a -cis-H 9,H 9a -trans-2-methyl-9-phenyl-2, 3,4,4 a ,9,9 a -hexahydro-1H-indeno[2,1-c]pyridine hydrochloride was determined. The compound crystallizes in the orthorhombic space groupPbca, with eight molecules in the unit cell of dimensionsa = 10.461(2),b = 20.141(10), andc = 15.469(3) Å. Intensity data were measured using Mo radiation and a θ−θ scan method. The structure was solved by direct methods and refined by least-squares techniques to a finalR of 4.6%. Thecis-trans isomer has higher antihistamine activity compared to thecis-cis isomer but is less active than phenindamine, the 2,3,4,9-tetrahydro derivative. The bond distances in thecis-trans andcis-cis derivatives are identical so that the differences in activity must be related to differences in conformation. The difference in the conformation is discussed from a receptor-site view of the two molecules.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 11 (1981), S. 87-103 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the muscle relaxant stercuronium iodide in the form of its ethanol solvate C26H43N2 +I− · C2H5OH, has been determined by the heavy-atom method and refined by block-diagonal least-squares toR o = 0.062 for 1941 observed reflections andR = 0.079 for a total of 2420 reflections measured on a four-circle diffractometer in the ω/2θ scanning mode. The crystals are monoclinic,P21,a = 15.386(5),b = 11.377(4),c = 8.307(3) Å, β = 98.22(2) °,Z = 2. RingsA andB in the modified conessine skeleton are both highly symmetrical half-chairs, ringC is in the chair conformation, and ringsD andE are highly symmetrical envelopes. The pyrrolidine ringE fused to ringD is roughly perpendicular to the steroid skeleton formed by ringsA toD. The N+---N distance of 10.76 Å is within the usual range required for potent neuromuscular blocking. Semiquantitative results are presented which suggest that the site of the tertiary N atom in ringE is not heavily congested by neighboring atoms in the molecule and may therefore be susceptible to protonation under physiological conditions. This could account for the relatively high drug potency of stercuronium.
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  • 7
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    Springer
    Journal of chemical crystallography 11 (1981), S. 117-124 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of 2-aminophenol has been redetermined from automatic diffractometer data in order to locate the hydroxyl and amino hydrogens and confirm the nature of the intermolecular hydrogen bonding. Crystals are orthorhombic, space groupPbca, witha =19.751(6),b = 7.250(3), andc = 7.852(5) Å, and eight molecules per cell. The structure was solved by Multan and refined to a conventionalR value of 0.030. The molecular geometry compares well with previously reported structures of related species. The molecules are hydrogen bonded from OH to N to form chains parallel to theb axis, with these chains linked together to form sheets by NH to O hydrogen bonds essentially parallel toc. The NH - O hydrogen bonds are 0.33 Å longer than the OH - N ones, and an explanation for this is provided which incorporates newly computed values for atomic electronegativities. Pairs of molecules are mutually hydrogen bonded across inversion centers. There are large cavities between the sheets which could conceivably result in easy intercalation of small foreign molecules, much as in the clathrates formed by urea and β-quinol.
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  • 8
    Electronic Resource
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    Springer
    Journal of chemical crystallography 11 (1981), S. 145-156 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystals of 5-ethyl-5-(3′-methylbut-2′-enyi) barbituric acid, mp 154° C, are monoclinic, space groupP21/c witha = 11.590(3) Å,b = 22.188(10),c = 10.195(4), β = 108.949(1)°, and Z = 8. The crystal structure was solved by direct methods and Fourier and difference-Fourier techniques, and refined by block least-squares procedure toR = 0.071 for 2983 observed data. Of the two molecules in the asymmetric unit, one is disordered and has been explained in terms of three different conformations of the 3′-methylbut-2′-enyl group. The molecules form ribbonlike structures, held together by N-H ... O=C hydrogen bonds. These ribbons are held together to form bilayers of barbiturate rings by van der Waals interactions between the 5-ethyl groups, with the bilayers held together by van der Waals interactions between the 5-(3′-methylbut-2′-enyl) groups.
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  • 9
    Electronic Resource
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    Springer
    Journal of chemical crystallography 13 (1983), S. 221-229 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract C18H10S2,M=290.34, monoclinic,P21,a=20.556(5),b=15.843(3),c=3.963(1) Å,β=92.79(2)° at 18°C,Z=4,D x =1.496 g cm−3,μ(Cu Kα)=3.53 mm−1. Full-matrix least-squares refinement resulted in a final conventionalR value of 0.036 for 2030 observed reflections. The average C-S bond distance is 1.747(16) Å, the S-S bond length is 2.074(1) Å. The torsion angles at the disulfide group are close to zero, at 3.5 and 0.8°. The carbon frameworks are nearly planar, and closely approximate symmetrymmm. Bond distances are comparable with those in related molecules.
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  • 10
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    Springer
    Journal of chemical crystallography 13 (1983), S. 231-239 
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The results of an X-ray structure determination of one of the three possible chloride salts of [Cr(en) F2(OH2)2]+ show the two fluoro ligands to betrans to each other. The purple crystals are monoclinic in the space groupC2/c-C 2h 6 , witha=11.409(3),b=9.319(2),c=10.260(3) Å,β=128.73(2)° andD c =1.73 g cm−3 forZ=4. Least-squares refinement based on 1341 independent observed reflections resulted in a finalR of 0.026. The molecule lies on a crystallographic two-fold axis, and the Cr-F, Cr-N, and Cr-O bond lengths are 1.885(1), 2.044(2), and 1.997(2) Å respectively. It is suggested that the ill-defined shoulder in the visible electronic spectrum of this complex is indicative of atrans dihalo geometry.
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