Crystal and molecular structures of 2′-nitro-4-aminobiphenyl and 2-amino-7-nitrofluorene

2′-nitro-4-aminobiphenyl (5), C₁₂H₁₀N₂O₂, crystallizes in the monoclinic space groupP2₁/c:a = 6.043(2),b =15.795(3),c = 11.577(2) Å, β = 103.42(8) °;D _c = 1.324 g cm^?3 forZ = 4. 2-amino-7-nitrofluorene (3), C₁₃H₁₀N₂O₂, crystallizes in the monoclinic space groupP2₁ n:a = 10.765(2),b = 7.454(4),c = 12.959(2) Å, β = 95.44(1) °;D _c = 1.451 g cm^?3 forZ = 4. Three-dimensional CuKα intensity data were measured with a computer-controlled diffractometer, and the initial phases were obtained by direct methods. The two structures were refined by the full-matrix least-squares method, which gave finalR values for 5 and 3 of 0.045 and 0.043, respectively. Bond lengths in the compounds are normal, apart from slight shortening of the phenyl-phenyl C-C bond and some distortion of the phenyl rings caused by the amino and nitro groups. In 5, the two phenyl rings are twisted by 57.1 °, and the nitro group is twisted by 34.6 ° from the plane of its phenyl group. The carbon backbone of 3 is nearly planar with the two phenyl groups tilted by 4.0 ° to each other. The nitro group in 3 is twisted 5.7 ° from the plane of its phenyl group. There is amino hydrogen to nitro oxygen intermolecular hydrogen bonding in each structure.     

Crystal structures of twoN-substituted 2-thioxo-1,3-dithiole-4-carboxamides

The two closely related compoundsN,N-dimethyl 5-(methylthio)-2-thioxo-1,3-dithiole-4-carboxamide1 andN-(p-methoxy-phenyl)-N-methyl 5-(methylthio)-2-thioxo-1,3-dithiole-4-carboxamide2 have been characterized by X-ray crystal structure determination. Crystal data for1: triclinic, ,a=6.767(1),b=12.594(2),c=6.648(1) Å, =101.38(1), =93.37(2), =79.62(1)°,V=546.2 ų,Z=2. Crystal data for2: monoclinic, Cc,a=19.836(4),b=6.057(1),c=15.860(3) Å, =127.61(3)°,V=1509.5ų,Z=4. The molecular structures of1 and2 show remarkable differences concerning the conformational behavior. These differences are related to the nature of the substituents at the nitrogen atom. The presence of an aromatic system in2 leads to an almost planar arrangement of the -oxoketene dithioacetal moiety. This effect is accompanied by a short intramolecular S...O contact of 2.648(2) Å. In the absence of an aromatic system, as is the case for compound1, neither a resonance effect along the -oxoketene dithioacetal fragment nor a short S...O distance is observed.     

Crystal and molecular structure of 1,3-diphenyl-4-p-chlorobenzal-5-pyrazolone

Crystals of 1,3-diphenyl-4-p-chlorobenzal-5-pyrazolone, C₂₂H₁₅ClNN₂O, are triclinic:a = 13.96,b = 12.94,c = 7.29 Å, = 93.0 ° = 100.1 °, = 135.6 °,Z = 2, space groupP¯1. The structure has been determined from Weissenberg X-ray data by direct methods, and refined by full-matrix least squares toR = 0.098 for 1949 observed reflexions. The molecular conformation of the double bond at chlorobenzal is of type Z. The phenyl rings make angles of 9.2 ° and 47.7 ° and thep-chlorophenyl group an angle of 4.2 ° all with the plane of the pyrazolone moiety, thus allowing extended conjugation. Comparisons of bond distances and angles with those of similar molecules are made. Close molecular packing is afforded by layers of molecules approximately parallel to (¯110).     

Crystal structures and vibrational spectra of racemic and chiral 4-phenyl-1,3-oxazolidine-2-thione

The crystal structures of (rac)- and (R)-4-phenyl-1,3-oxazolidine-2-thione (4-POT) have been determined by X-ray diffraction. The structure of (rac)-4-POT is monoclinic P2₁/n with a = 11.9096(9) Å, b = 5.9523(6) Å, c = 12.3563(8) Å, = 91.054(6)°, V = 875.8(1) ų, and Z = 4. The structure of (R)-4-POT is orthorhombic P2₁2₁2₁ with a = 7.7197(6) Å, b = 21.603(2) Å, c = 5.4613(9) Å, V = 910.8(2) ų, and Z = 4. (rac)-4-POT and (R)-4-POT crystals are shown to have different hydrogen-bonding patterns. In the racemic crystals, the enantiomeric (R)- and (S)-4-POT molecules are connected to form a cyclic dimer via the N–H S hydrogen bond of the cis thioamide moiety [N Sⁱ 3.438(2) Å, N–H Sⁱ 176(2)° symmetry code: (i) 1 – x, 1 – y, 1 – z]. In the chiral (R)-4-POT crystals, the N–H S intermolecular hydrogen bond forms a zigzag chain around the twofold screw axis [N Sⁱⁱ 3.347(3) Å, N–H Sⁱⁱ 161(3)° symmetry code: (ii) 1/2 + x, 1/2 – y, 2 – z]. Observed difference of 46°C in the melting points between the (rac)-4-POT and (R)-4-POT crystals is correlated with difference in the crystal packing. Vibrational spectra of (rac)- and (R)-4-POT crystals are discussed both in the solid state and in solution.     

Crystal and molecular structures of 11-hydroxy-7-oxodrim-8(9)-ene

The crystal structure of 11-hydroxy-7-oxodrim-8(9)-ene is determined. The crystals are monoclinic. The unit cell parameters are a = 16.716(4) Å, b = 11.052(3) Å, c = 7.542(3) Å, γ = 76.11°, Z = 4, μ = 1.476 cm⁻¹, ρ_calcd = 1.147 g/cm³, and space group P2₁. The structure is solved by the direct method and refined by the least-squares procedure to R = 0.045. There are two molecules of 11-hydroxy-7-oxodrim-8(9)-ene in the asymmetric unit. Both molecules have the same conformation of the skeleton and can be described as rotomers differing in orientation of the OH groups with respect to the skeleton. In both molecules, the cyclohexane rings have a usual chair conformation. In the crystal, two independent molecules are linked by a hydrogen bond. The molecular pairs related by the twofold screw axes are linked by hydrogen bonds into helices running along the z-axis of the crystal. The helices are bound through van der Waals interactions. __________ Translated from Kristallografiya, Vol. 45, No. 2, 2000, pp. 275–278. Original Russian Text Copyright ? 2000 by Chumakov, Simonov, Mazus, Popa, Vlad. Deceased.     

Crystal and molecular structure of 1,1,2-trifluorobuta-1,3-diene

A single crystal of 1,1,2-trifluorobuta-1,3-diene, m.p. –108°C, was obtained by in situ crystallization in a capillary directly on a diffractometer. 1,1,2-Trifluorobutadiene crystallizes monoclinic, space group Pc, a = 4.4030(12), b = 6.4160(16), c = 8.293(3) Å, = 91.728(14)°, V = 234.17(12) Å, d _calc = 1.5326 g cm^–3, Z = 2, wR ₂ = 0.1332. The 1,1,2-trifluorobutadiene molecules have an anti conformation, C4–C3–C2–C1 179.17(1)°. There is no fluorine substitution effect on the bond lengths of the conjugated C–C double bonds, C1–C2 1.331(3), C3–C4 1.336(4) Å. The central bond C2–C3 1.436(4) Å is shorter than a single bond because of conjugation. The C–F bond lengths of the CF₂ group are significantly shorter than the one of the CF moiety.     

Crystal and molecular structures of benz-p-nitroanilide and benz-p-methoxyanilide

The crystal structures of the two carboxylic amides C₁₃H₁₀N₂O₃ (I) and C₁₄H₁₃NO₂ (II) have been determined by direct methods and refined by full-matrix least squares. The predominant structural feature is the hydrogen bonding (N-H?O=C) which influences the conformations of both structures.     

Crystal and molecular structures of two polymorphs of 4-methyl-2-nitroacetanilide (MNA)

Journal of Chemical Crystallography - The crystal and molecular structure of white (MNA-1) and yellow (MNA-3) forms of 4-methyl-2-nitroacetanilide have been determined by X-ray diffraction...     

Crystal and molecular structure of 2-diazo-5-phenyl-cyclohexan-1,3-dione

M_r = 214.24, monoclinic space group P 2₁, a = 10.964(2), b = 5.870(2), c = 8.574(2) Å, β = 98.09(2)°, V = 546(1) ų, Z = 2, D_x = 1.302 Mg m⁻³, F(000) = 224, λ (MoKα) = 0.71069 Å, μ = 0.8 mm⁻¹. The crystal structure was determined by direct methods and refined by least-squares procedure to the discrepancy factor R = 0.034. M_r = 214.24, monokline Raumgruppe P 2₁, a = 10.964(2), b = 5.870(2), c = 8.574(2) Å, β = 98.09(2)°, V = 546(1) ų, Z = 2, D_x = 1.302 Mg m⁻³, F(000) = 224, λ(MoKα) = 0.71069 Å, μ = 0.8 mm⁻¹.     

Crystal and molecular structure of 1-hydroxy-2,3-dicarbomethoxy-1,3-cycloheptadiene

The crystal structure of 1-hydroxy-2,3-dicarbomethoxy-1,3-cycloheptadiene has been determined from three-dimensional counter data, and refined by full-matrix least-squares techniques. The crystals belong to the triclinic space groupP¯1, witha = 10.721(7),b = 8.628(6),c = 6.214(6) Å, = 91.65(5), = 83.14(5), = 81.66(5) °, andD _c = 1.33 g cm^–3 forZ = 2. The finalR factor for 1385 observed reflections is 0.058. The compound exists in the enolic configuration.     

Crystal and molecular structure of 4-aminoacetyl-N-p-nitrophenylsulfanilamide

The crystal and molecular structure of 4-aminoacetyl-N-p-nitrophenylsulfanilamide (C₁₄H₁₃N₃O₅S), a derivative of sulfonamide, has been determined from X-ray diffraction data using Cu-K radiation. The compound crystallised in the monoclinic space groupP2₁/c, witha=12.258(9),b=7.339(5),c=16.359(9) Å,=98.84(4)°. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR value of 0.047 with 2487 unique reflections. In packing, the molecules are found to be stabilised by N-H O hydrogen bonds.     

Crystal and molecular structure of C.I. Solvent Yellow 2, 1-phenylazo-4 (N,N-dimethylamine)-phenyl

The crystal structure of C.I. Solvent Yellow 2, C₁₄H₁₅N₃, has been determined by single crystal X-ray diffraction techniques. It crystallizes in the orthorhombic system witha=6.059(2) Å,b=7.398(1) Å,c=27.467(4) Å, space groupP2₁2₁2₁,Z=4. The structure has been solved by direct methods and least-squares has been completed on three dimensional data (688 reflections, MoK radiation). The hydrogen positions have been found but only their positional parameters refined. Final residual 0.055 (all positive intensity data). The molecule exists as an azo-compound and is almost planar. The molecules are packed in columns parallel to theb axis, within each column they are packed in layers almost parallel to the (130) or (130) plane depending on the column. The molecules are linked by van der Waals' forces.     

Crystal and molecular structure of 4-cyanopyridine-N-oxide

Crystals of 4-cyanopyridine-N-oxide crystallize in space groupP2₁/c (No. 14). There are four molecules per unit cell, witha = 7.88(2),b = 6.10(2),c =11.61(3) Å and =101.4(4) °. Data for 838 unique reflections were recorded using the multiple-film technique and visually estimated intensities. A three-dimensional least-squares refinement of the structure was carried out to a final conventionalR of 0.098. It was found that the molecule was planar, as expected, and that the centrosymmetric pairs were stacked parallel to each other, as viewed down thea-axis. Bond distances and angles are in agreement with those from comparable molecules.     

Crystal and molecular structures of dimethyl 4-phenylthiosemicarbazidediacetate and its adduct with rhodium(II) acetate

The crystal structures of dimethyl 4-phenylthiosemicarbazidediacetate C₁₃H₁₇N₃O₄S (I) and its adduct [C₈H₁₂O₈Rh₂ (C₁₃H₁₇N₃O₄S)₂] (II) with rhodium(II) acetate are determined by X-ray diffraction analysis. The unit cell parameters of crystals I are as follows: a = 8.066(6) Å, b = 15.812(6) Å, c = 24.977(8) Å, β = 94.88(3)°, space group P2₁/n, and Z = 8. The unit cell parameters of crystals II are a = 8.513(1) Å, b = 16.055(1) Å, c = 16.071(3) Å, β = 104.99(1)°, space group P2₁/c, and Z = 2. In structure I, two crystallographically independent molecules considerably differ from each other in the mutual orientation of the structural fragments containing the ester groups. In the centrosymmetric dimeric complex II, the organic molecule I acts as a monodentate thio ligand and adopts only one conformation.     

Crystal and molecular structure of 2-isopropylidene-5-methyl-1,3-dithiolane-1-oxide,C7H12OS2

The acid catalyzed cyclization of 2-propyl(allylthio)sulfine to methyl substituted 2-isopropylidene-1,3-dithiolane-1-oxide occursvia enethiolization of the sulfine followed by an intramolecular addition of thus formed sulfenic acid to the olefinic bond. Crystal data: C₇H₁₂OS₂,M _r=176.3, orthorhombic, space group Pbca,a=9.5551(13),b=17.3407(18),c=10.6417(9)Å,V=1763.2(3)ų,Z=8. The structure was solved by a combination of Patterson and direct methodswR ₂=0.115 for 1554 observations and 106 parameters. The stereochemical relationship between the methyl and sulfoxide oxygen iscis.     

Crystal and molecular structure of 4-amino-4-carboxyl thiapyran

4-Amino-4-carboxylthiapyran crystallizes in space groupP2₁/c witha = 10.61,b = 6.55,c= 10.97 Å, =96.3 °, andZ = 4. The structure was solved by the heavy-atom method, with 897 observed reflections, and refined to anR of 0.093. The packing of the structure is found to be very similar to that in the structure of 1-aminocyclohexane carboxylic acid. The conformation of the thiapyran ring exists in the puckered chair form.Contribution No. 410 from the Dept. of Crystallography and Biophysics, Univeristy of Madras, Guindy Campus, Madras-600025, India.     

Crystal and molecular structures of the monoclinic and orthorhombic modifications ofo-bromophenylazocarbamide

The crystal and molecular structures of two polymorphs ofo-bromophenylazocarbamide (C₇H₆N₃OBr) have been determined and refined by Fourier methods, using three-dimensional X-ray data collected at room temperature by photographic techniques. The unit cell parameters are, for the monoclinic modificationa = 25·20(1),b = 5·03(1),c = 14·01(1) Å, β = 105·5(1·0)°,Z = 8, space groupC2/c; for the orthorhombic modification,a= 14·02(1),b = 5·04(1),c = 24·32(3) Å,Z = 8, space groupPca2₁. In both polymorphs a rather large thermal effect is present, being greater for the orthorhombic phase. Corresponding bond distances and angles are equal in both structures to within 1σ. The double bond is virtually localized in theazo group, so that there is no conjugation between the bromophenyl and the carbamidic groups. NH···O hydrogen bonds link the molecules in ribbons, which are parallel in the monoclinic modification and mutually tilted (76·7 °) in the orthorhombic structure.