Flukicides. IV. Crystal and Molecular Structure of 3'-Chloro-4'(p-chlorophenoxy)-3,5-diiodo-salicylanilide (Rafoxanide)

1980 ◽  
Vol 33 (1) ◽  
pp. 203 ◽  
Author(s):  
A Sindt ◽  
M Mackay

Orthorhombic crystals of rafoxanide, C19H11Cl2I2NO3, belong to the space group Pca21 with a 23.234(2), b 8.980(2), c 9.582(2)Ǻ and Z 4. The structure was solved by the heavy-atom method from diffractometer data measured with Mo Kα radiation. Refinement with anisotropic temperature factors given to the non-hydrogen atoms converged at R 0.059 for the 2025 observed terms. The two aromatic rings of the salicylanilide moiety are almost coplanar with a dihedral angle of 11.2°, whereas they are approximately perpendicular to the plane of the phenoxy group. Weak inter-molecular hydrogen-bond-like interactions between the nitrogen and carbonyl oxygen, which involve a glide motif, link the molecules into ribbons extending along the c axis.


1994 ◽  
Vol 59 (5) ◽  
pp. 1052-1058 ◽  
Author(s):  
Jan Ondráček ◽  
Jana Ondráčková ◽  
Jaroslav Maixner ◽  
František Jursík

The crystal and molecular structure of s-fac-[Co((S)-Asp)(dien)]ClO4 . HClO4 .2 H2O (dien = 1,4,7-triazaheptane) was solved by the heavy atom method. The position parameters of the non-hydrogen atoms and their anisotropic temperature parameters were refined based on 1 726 observed reflections with a final value of R = 0.073. The substance crystallizes in the orthorhombic system in the space group P212121, Z = 4, a = 8.506(1), b = 17.171(2), c = 13.277(1) Å. The structure involves hydrogen bonds between the O2, O4 and HN2 atoms of aspartic acid and the two molecules of water. The five-membered dien chelate rings take the asymmetric envelope conformations. The five-membered ring of (S)-aspartic acid possesses the symmetric envelope conformation whereas the six-membered ring exhibits the skew boat conformation.



1989 ◽  
Vol 54 (12) ◽  
pp. 3220-3229
Author(s):  
Jan Ondráček ◽  
Jaroslav Maixner ◽  
Bohumil Kratochvíl ◽  
Jana Ondráčková ◽  
František Jursík

The crystal and molecular structure of unsym1-fac-Λ-(δ, chair)-(S)-[Co(aepn)(S)-Asp]ClO4(trans-6,6) was solved by the heavy atom method. The positions of the non-hydrogen atoms and their anisotropic temperature parameters were refined on the basis of 1 935 observed reflections, yielding values of R = 0.121 and wR = 0.117, affected by the undertermined position of the oxygen atoms in the ClO4-> anion. The substance crystallizes in the orthorhombic system with space group P212121; Z = 4, a = 9.664(1), b = 11.805(1), c = 13.966(2) Å. The secondary atom of the triamine has S configuration, the conformation of the five-membered chelate ring approaches that of the asymmetrical δ envelope and the six-membered ring has chair configuration. Both conformations are deformed. The donor atoms deviate from the defined planes and thus form further sources of chirality (λ) contributing to the optical activity of the isomer. These deviations lead to the similarity of the CD spectra of the isomers.



Author(s):  
H. M. Maurer ◽  
Alarich Weiss

AbstractThe crystal structure of diamminesilver dinitroargentate, [Ag(NHThe point positions of the silver atoms were obtained by the heavy-atom method whereas those of the light atoms were found by difference Fourier syntheses. Coordinates and anisotropic temperature factors were refined by block-diagonal least-squares methods with the result



1993 ◽  
Vol 58 (2) ◽  
pp. 335-342 ◽  
Author(s):  
Jan Ondráček ◽  
Jaroslav Maixner ◽  
Jana Ondráčková ◽  
František Jursík

The crystal and molecular structure of s-fac-[Co((S)-Asp)(medien)]ClO4 . H2O . HClO4 was elucidated by the heavy atom method. The positional parameters of the nonhydrogen atoms and their anisotropic temperature parameters were refined based on 2 474 observed reflection with final values of R = 0.0603 and wR = 0.0616. The substance crystallized in the orthorhombic system in the space group P212121, Z = 4, a = 8.536(1), b = 13.378(1), c = 16.899(2) Å. The structure comprises layers of the complex cation which alternate with layers containing two perchlorate anions and one hydroxonium cation. The five-membered chelate ring of 4-methyl-1,4,7-triazaheptane exist in the asymmetric λ, δ envelope conformations and the N-CH3 group of the triamine has the exo orientation. The five-membered ring of (S)-aspartic acid assumes the symmetric envelope conformation, the six-membered chelate ring, the skew boat conformation.



1970 ◽  
Vol 48 (2) ◽  
pp. 307-311 ◽  
Author(s):  
H. Lynton

The molecular structure of the m-bromobenzoate derivative of bisnorquassin, C27H27O7Br, has been determined by the heavy atom method. The compound crystallizes in the orthorhombic system, space group P212121, with unit cell dimensions a = 20.09 ± 0.02 Å, b = 14.63 ± 0.02 Å, c = 8.06 + 0.01 Å and 4 molecules in the unit cell. Final atomic parameters have been obtained from a blockdiagonal least-squares refinement using anisotropic temperature parameters. The final agreement residual for 1665 observed reflections is R = 0.107.The structure of bisnorquassin previously proposed by Findlay and Cropp, on the basis of spectroscopic and chemical evidence, is shown to be essentially correct.



1987 ◽  
Vol 52 (4) ◽  
pp. 949-956 ◽  
Author(s):  
Bohumil Kratochvíl ◽  
Jan Ondráček ◽  
Jana Ondráčková ◽  
Jiřina Soldánová ◽  
František Jursík ◽  
...  

The crystal and molecular structure of sym-fac-[Co-(aepn) (S)-Asp]ClO4 was solved by the heavy atom method. The positions of the nonhydrogen atoms and their anisotropic temperature factors were refined. On the basis of 1 514 observed reflection intensities, a final reliability factor value of R = 0.096 was obtained (wR = 0.101). The substance crystallizes in the orthorhombic system in the P212121 space group. The elementary cell contains four formula units and has dimensions of a = 704.0(6), b = 939.4(7), c = 2 369(2) pm. The secondary nitrogen atom of the triamine has S confuguration. The five-membered ring has the λ conformation and the six-membered ring the flattened chair conformation. Selected structural parameters indicate that facial coordination of N-2-aminoethyl-1,3-diaminopropane leads to decreased strain in the coordinated, slightly deformed octahedron than meridional coordination and also that the chelate rings of the triamine are conformationally dependent. The bond lengths and angles of the part formed by (S)-aspartic acid agree with the corresponding values in [Co-((S)-Asp)2]-.



1990 ◽  
Vol 55 (4) ◽  
pp. 1010-1014 ◽  
Author(s):  
Jiří Kameníček ◽  
Richard Pastorek ◽  
František Březina ◽  
Bohumil Kratochvíl ◽  
Zdeněk Trávníček

The crystal and molecular structure of the title compound (C8H16N2NiS4) was solved by the heavy atom method and the structure was refined anisotropically to a final R factor of R = 0.029 (wR = 0.037) for 715 observed reflections. The crystal is monoclinic, space group P21/c with a = 948.3(2), b = 776.9(2), c = 1 167.4(2) pm, β = 125.14(2)°, Z = 2. The molecule contains two four-membered NiSCS rings of approximately planar configuration with the Ni atom situated at a centre of symmetry. The molecules are arranged in chains along the c-axis of the unit cell.



1984 ◽  
Vol 62 (3) ◽  
pp. 601-605 ◽  
Author(s):  
Masood A. Khan ◽  
Clovis Peppe ◽  
Dennis G. Tuck

The crystal structure of the title compound has been determined by the heavy atom method. The crystals are orthorhombic, space group Pbca, with unit cell dimensions a = 22.795(3) Å, b = 17.518(2) Å, c = 12.396(3) Å, Z = 8; R = 0.0409 for 1527 unique "observed" reflections. The structure is disordered, with each halogen site (X) occupied by 75% Br, 25% I. The molecule consists of two X2(tmen)In units (tmen = N,N,N′,N′-tetramethylethanediamine) with distorted trigonal bipyramidal geometry, joined by an In—In bond 2.775(2) Å in length.



1976 ◽  
Vol 54 (19) ◽  
pp. 3001-3006 ◽  
Author(s):  
William Edward Lee ◽  
Mary Frances Richardson

The X-ray crystal structure of thiamine iodide hydroiodide, C12H18N4OSI2, has been determined. The unit cell parameters are: a = 13.835(7), b = 7.442(4), c = 20.243(9) Å, β = 120.52(7)°, monoclinic space group P21/c, Z = 4. A total of 1445 reflections having F2 > 2σ(F2), 2θ < 40° were collected on a Picker 4-circle diffractometer with MoKα radiation by the 2θ scan technique. The structure was solved by the heavy-atom method. The iodide and sulphur atoms were refined anisotropically; only positional parameters were refined for the hydrogen atoms. Successive full-matrix least-squares refinements yielded an unweighted R-factor of 0.054. The pyrimidine ring is protonated on the ring nitrogen opposite the amino group. The relative disposition of the pyrimidine and thiazolium rings is similar to that observed in most other thiamine structures. The β-hydroxyethyl side chain of the thiazolium ring is folded in such a way that there is a short S … O contact, 2.97 Å in length. The iodide ions are involved in a number of weak hydrogen bonds.



1975 ◽  
Vol 53 (22) ◽  
pp. 3383-3387 ◽  
Author(s):  
Joseph Hubert ◽  
André L. Beauchamp ◽  
Roland Rivest

The crystal and molecular structure of dithiocyanato(triphenylarsine)mercury(II) has been determined from X-ray diffraction data. The crystals are monoclinic, space group P21/c, with a = 10.290(7), b = 21.199(23), c = 10.719(7) Å, β = 112.00(2)°, and Z = 4. The structure has been solved by the heavy-atom method and refined by block-diagonal least-squares calculations. The agreement factor R obtained for 2607 'observed' reflections is 0.030. The crystal consists of single molecules. The 'characteristic' coordination number of mercury is three, with two sulfur and one arsenic atoms at the apexes of a triangle. The nitrogen atoms of the thiocyanate groups are at 2.67 and 2.74 Å from the adjoining mercury atoms and therefore link the different molecules together.



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