Structure of 5-benzoylamino-5-methyl-4-oxo-1,3-dioxane

The crystals of the title compound (C₁₂H₁₃NO₄) are orthorhombic,P2₁2₁2₁ witha=8.541(3),b=10.988(1), andc=11.912(1) Å.M _r =235.24, mp 427 K,Z=4,D _x =1.348 Mg m^–3, (MoK=0.71069 Å, =0.11 mm^–1,T=293 K. The structure was solved by direct methods and refined by full-matrixs least squares to a finalR=0.028 for 1180 observed reflections. The molecules are connected by N-HO (ring carbonyl) intermolecular HO hydrogen bonds of 2.24(2) Å. The 4-oxo-1,3-dioxane ring is in a slightly distorted sofa conformation with a C _s ¹ asymmetry parameter of 3.6(2)° and the 5-methyl substituent in a pseudoaxial position. The benzoyl oxygen is turned toward the ring, resulting in a close OH(C6) contact of 2.45(2) Å.     

Crystal structure of racemic 5-(p-nitrobenzoylamino)-5-methyl-4-oxo-1,3-dioxane

C₁₂H₁₂N₂O₆ crystallized from methanol in the monoclinic space group P2₁/c (Z=4) witha=13.333(4),b=10.154(3),c=9.597(2) Å and=102.37(2)°.M _r=280.24,V=1269.1(6) ų,D _x=1.466 g cm^–3,(Mo K)=0.71069 Å,=1.29 cm^–1,T=295 K. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR (R _w)=0.049 (0.057) for 916 observed reflections. The molecules are linked by strong N-HO(4) hydrogen bonds with NO distance of 2.995(4) Å. The infinite racemic chains run in [001] direction.     

Crystal and molecular structure of 5-diazo-2,2-dimethyl-4,6-dioxo-1,3-dioxane and 5-diazo-1,3-dimethylpyrimidin-2,4,6-trione

C₆N₂O₄H₆: M_r = 170.12, orthorhombic space group Pbca, a = 6.751(2), b = 13.669(4), c = = 16.845(4) Å, V = 1555(1) ų, D_x = 1.248 Mgm⁻³, Z = 8, F(000) = 704, λ(moKα) = 0.71069 Å, μ = 1.1 mm⁻¹. The crystal structure was determined by direct methods and refined by least-squares procedure to the discrepancy factor R = 0.039. C₆N₄O₃H₆: M_r = 182.14, monoclinic space group C2/c, a = 17.726(8), b = 6.191(12), c = 16.062(6) Å, β = 117.59 (3)°, V = 1562 (1) ų, D_x = 1.549 Mgm⁻³, Z = 8, F(000) = 752, λ(MoKα) = 0.71069 Å, μ = 1.2 mm⁻¹. The crystal structure was determined by direct methods and refined by least-squares procedure to the discrepancy factor R = 0.056.     

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).     

The Crystal and Molecular Structure of the Smectogenic Compound 5-Hexyl-2-(4-bromophenyl)-1,3-dioxane

The title compound with the formula C₆H₁₃ C₄O₂H₆ C₆H ₄Br (HBPD) crystallizes in the monoclinic space group C 2/c with lattice parameters a = 28.48 Å, b = 5.71 Å, c = 20.19 Å, β = 97.4° and molecules per unit cell. The structure has been solved by the heavy atom method and refined to a final R value of 0.094. – The HBPD molecules adopt a fully stretched form, both the alkyl and phenyl substituent are in equatorial position with respect to the chair-shaped dioxane ring. The orientation of the phenyl group is an intermediate between the perpendicular and parallel conformation. The molecules show a nearly perfect parallel arrangement in the crystal lattice.     

Crystal and molecular structure oftrans-1-isopropyl-1-methyl-4-acetyl-4-phenylpiperidinium iodide

The crystal structure oftrans-1-isopropyl-1-methyl-4-acetyl-4-phenylpiperidinium iodide has been determined from single-crystal X-ray data and refined by least-squares methods toR=0.052. The orthorhombic crystals have unit-cell dimensions ofa=10.792(6),b=11.594(8),c=13.746(9) Å, space groupP2₁2₁2₁, andZ=4. The piperidine ring is in the chair form with the bulky substituents, the isopropyl and the phenyl groups, respectively in equatorial and axial positions.     

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.     

Molecular structure of isopropyl 1-phenyl-4-phenylhydrazono-5-oxo-3-pyrazolecarboxylate

The new azopyrazolone dye has been synthesized and its crystal structure has been investigated. Crystals of C₁₉H₁₈N₄O₃ are triclinic: ,a=7.484(1),b=10.646 (1),c=11.897(1) Å, =82.28(1), =72.86(1), =86.83(1)°,Z=2. The structure has been solved by direct methods and refined by full-matrix least-squares techniques toR=0.050 for 2622 unique reflections. The tautomeric form of the molecules has been determined as a hydrazo form. Delocalization of the C5=O3 and C4=N3 -electrons and delocalization of the lone-pair electrons of N1, N3, and N4 atoms has been observed. The intramolecular N–H...O hydrogen bond forms the six-membered ring C₂N₂H...O condensed with the pyrazolone ring. The molecules are connected by intramolecular C–H...O hydrogen bonds.     

Crystal structure of 1,3 diphenyl-5-carbethoxymethylene-1H-4,5-dihydro-1,2,4-benzotriazepine

C₂₄H₂₁N₃O₂ is orthorhombic,P2₁2₁2₁,a = 15.1342(3),b = 14.1692(3),c = 9.6533(3) Å,Z = 4,D _m = 1.23 g cm^–3. The structure was solved by direct methods, and refined to anR of 0.048 (R _w = 0.068) for 1831 observed reflections. An intramolecular hydrogen bond is present. The conformation of the seven membered ring is boatlike with a quasi-mirror plane through N(1).     

Crystal structure of 2,4-di-para-methoxyphenylcyclobutadiene-1,3-quinone

The crystal structure of 2,4-di-p-methoxyphenylcyclobutadiene-1,3-quinone has been been determined using three-dimensional X-ray data collected by means of a Picker FACS-1 four-circle diffractometer. The crystal used was one of four modifications of this compound, two low density (1.38 g cm^?3) and two high density (1.54 g cm^?3) forms, obtained by us, depending on crystallization conditions. The space group isP¯1, with unit cell dimensionsa = 3.89,b = 10.80,c = 9.03 Å, α = 77.88, β = 74.12, γ = 85.15 °D _m = 1.38 g cm^?3 andZ = 1. A least-squares refinement of the positional and anisotropic thermal parameters gave a finalR-value of 6.0% for 364 reflections and 121 variables. The zwitter-ionic nature of the molecule can be seen in both the partial delocalization of the bonds in the 4-membered ring (which is square-planar) and the bonds joining thep-phenylene and 4-membered rings. The nearly planarp-phenylene rings themselves are quinone-like in structure and are parallel, but not coplanar. The columnar packing of the molecules resembles that of graphite, and observed interplanar spacing is 3.64 Å.     

Dielectric and Electrooptic Investigations in the Nematic Phase of 5-n-Pentyl-2-[4-n-nonyloxyphenyl]-1,3-dioxane

The dielectric constant and the dielectric loss of 5-n-pentyl-2-[4-n-nonyloxyphenyl]-1,3-dioxane were investigated in the region of 0.1 to 10 MHz. An isotropy temperature was detected, at which the static dielectric anisotropy Δε₀₁ = 0. Using both the Freedericksz and the DAP effect, we measured the frequency dependence of the threshold voltage U₀ and compared the results with those of the dielectric measurements. In the case of DAP effect we could find two different types of dispersions curves of U₀.     

Crystal structure of 1,1-diphenyl-2,4-dimethyl-5-(N-benzamide)-1,3-pentadiene

Crystals of the title compound are monoclinic (C₂₆H₂₅NO): space groupP2₁/c,a=16.565(3),b=10.328(2),c=12.621(3) Å,=104.02(3)°. The structure was solved by direct methods and refined by block-matrix least-squares to giveR=0.056 andR _w =0.061 for 1613 reflections above 2(I). The amide moiety is tilted by 19.3(2)° with respect to the mean aromatic ring plane. The two othergem phenyl rings subtend a dihedral angle of 112.2(4)° to each other. The molecules are joined in the solid by N-HO hydrogen bonds.     

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.