Crystal structure and packing analysis of the liquid crystal dimer alpha,omega-bis(4-cyanobiphenyl-4-yloxy)octane

The crystal structure of the liquid crystal dimer α,ω-bis(4-cyanobiphenyl-4'-yloxy)octane has been determined from diffraction data obtained with synchrotron radiation. The structure is triclinic, with the space group P-1 with Z = 2 and the unit cell parameters are a= 7.135(5) Å, b= 12.811(5) Å, c= 15.639(5) Å, α= 75.800(5)°, β= 84.690(5)°, γ= 77.930(5)°. The flexible spacer linking the mesogenic groups is in the all-trans-conformation. Although the molecule has a potential centre of symmetry, it occupies a general position in the cell; this unusual behaviour has been investigated with the aid of a theoretical evaluation of the packing energy.     

Semiconducting polymers based on charge-transfer complexes. II. Crystal structure of poly-N-4-[4-(methylthio)phenoxy]butyrylethylenimine

Of the two electron-donor-containing polymers whose synthesis was described in Part I of this series, one was crystalline. This polymer, which contains (methylthio)phenoxy electron-donating groups on the side chains of an N-acyl-substituted polyethylenimine, could be indexed in a triclinic unit cell of dimensions a = 4.35 Å, b = 24.0 Å, c = 12.7 Å, and α = β = γ = 90°. The polymer has the side chains alternating on each side of the polymer backbone. They extend to form at 24.0 Å repeat in that direction. The thickness of the ribbonlike molecule is 4.35 Å, while the repeat distance along the polymer backbone is 12.7 Å, which includes four monomer units.     

Solid-state conformations of medium-sized-ring phosphorus heterocycles: Preparation and x-ray crystal structure of a benzo-fused 1,3,2-dioxaphosphepane in a twist conformation

The crystal and molecular structure of the benzo-fused seven-membered-ring phosphorus heterocycle, 2-phenyl-2-oxo-5,6-benzo-1,3,2-dioxaphosphepane, has been determined by single-crystal X-ray techniques. The compound crystallizes in the monoclinic space group P 2₁/c with four molecules per unit cell of dimensions a = 13.312(1) Å, b = 7.6132(8) Å, c = 12.119(2) Å, and β = 95.990(9)°. Full-matrix leastsquares refinement led to R = 4.4% and R_w = 5.9%. The conformation adopted by the 1,3,2-dioxaphosphepane ring is a twist with approximate C₂ symmetry.     

Crystal structure and radiation-induced solid-state polymerization of 1,3,5,7,9,11-hexoxecane

One of the cyclic oligomers of formaldehyde, 1,3,5,7,9,11-hexoxecane, was found to undergo polymerization in the solid state to form polyoxymethylene both during and subsequent to x- or γ-irradiation. The polymer yield increases with polymerization temperature but decreases drastically near the melting point of the hexoxecane crystal. In order to clarify the specificity of the solid-state polymerization, the crystal structure of hexoxecane was first analyzed; hexoxecane forms a trigonal crystal with cell dimensions of a = b = 7.917 Å, c = 11.345 Å, space group R3 –C_3i², three molecules of 3 symmetry per unit cell. The polyoxymethylene as polymerized from a single crystal of hexoxecane is highly crystalline and the crystallites are definitely oriented with respect to the original crystal. There are three kinds of oriented trigonal polyoxymethylene: i.e., with the polymer chains oriented along the 〈100〉, 〈001〉, and 〈210〉 axes of the hexoxecane crystal. The relative yields of these crystallites depend upon the polymerization temperature. In addition to the ordinary trigonal polyoxymethylene, oriented orthorhombic polyoxymethylene was also found in the case of polymerization during treatment with x-rays.     

Crystal Structure Determination of Tetrabarium‐digalliumoxide,Ba4Ga2O7

Single crystals of a new barium oxogallate were obtained by growth from a melt at 1500 °C. The compound is monoclinic, with cell parameters a = 17.7447(10) Å, b = 10.6719(5) Å, c = 7.2828(5) Å, β = 98.962(7)°, V = 1362.3(2) ų. The diffraction pattern shows systematic absences corresponding to the space group P12₁/c1. The structure was solved by direct methods followed by Fourier syntheses, and refined using a single crystal diffraction data set (R1 = 0.032 for 2173 reflections with I > 2σ(I)). The chemical composition derived from structure solution is Ba₄Ga₂O₇, with a unit cell content of Z = 6. Main building units of the structure are GaO₄ tetrahedra sharing one oxygen atom to form Ga₂O₇ groups. The Ga–O–Ga bridging angle of one of the two symmetrically independent groups is linear by symmetry. The dimers are crosslinked by barium cations coordinated by six to eight oxygen ligands.     

Crystal structure of poly(m-phenylene isophthalamide)

The crystal structure of poly(m-phenyulene isophthalamide) was determined by x-ray analysis. The triclinic cell, with a = 5.27 Å, b = 5.25 Å, c (fiber axis) = 11.3 Å, α = 111.5°, β = 111.4° and γ = 88.0° and space group P1, contains one monomeric unit. The crystal density is 1.47 g/cc. The molecules in the crystal are contracted by 1 Å per monomeric unit from the fully extended conformation, and the planes of the benzene rings and adjacent amide groups make angles of about 30°. The crystal is composed of molecular chains connected by N? H···O hydrogen bonds along the a and b axes forming a “jungle gym” network structure. The low tensile modulus of this polymer as compared with that of poly(p-phenylene terephthalamide) is attributed to the contracted molecular conformation.     

Crystal structure of optically active poly(isopropylethylene oxide)

The crystal structure of optically active poly(isopropylethylene oxide) was analyzed by x-ray diffraction. Two molecular chains having twofold screw symmetry pass through an orthorhombic unit cell with parameters a = 12.85 Å, b = 7.52 Å, and c (fiber period) = 5.55 Å and space group P2₁2₁2₁-D. The crystal structure was refined by the constrained least-squares method. The molecular structure consists mainly of ?TG sequences and is very similar to the (9/4) helical structure in poly(tert-butylethylene oxide).     

A Highly Stable 3D Porous Lanthanum Metal‐organic Framework Constructed From A New Flexible Bis(benzoic acid) Ligand Produced in Situ

By employing diethyl 1,3‐propylidenebis(4‐oxybenzoate) as a precursor, the new three‐dimensional metal‐organic framework [La₂L₂(HL)₂]_n [L = 1,3‐propylidenebis(4‐oxybenzoate)] was prepared and characterized by single‐crystal X‐ray diffraction analysis, elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The compound crystallizes in the triclinic space group P , with cell parameters: a = 8.299 (2) Å, b = 14.127 (3) Å, c = 14.520 (3) Å, α = 112.43 (3) °, β = 103.10 (3) °, γ = 95.28 (3)°, V = 1502.2 (5) Å³, and Z = 1. Under hydrothermal reaction conditions, two ester groups of the ligand hydrolyzed into carboxylate groups. The carboxylate groups coordinated in situ to metal ions to form the 3D coordination polymer. It exhibits a 10.4 × 10.6 Å rhombic channel along the [011] direction. On the basis of the results of TG analysis, the structure is thermally stable up to ≈? 400 °C.     

Solid-state polymerization of butadienes. Crystal structure and solution properties of a stereoregular amphoteric 1,4-trans-polybutadiene

The double salt 1 consisting of the hydrochloride of 6-amino-2,4-trans-hexadienoic acid and cadmium chloride in a 2:1 stoichiometry polymerizes in the crystalline state if exposed to UV or γ irradiation. A stereoregular polymeric ampholyte is formed in an extended chain macroconformation, embedded in an inorganic matrix. The crystal structure of the polymerized crystals and the solution properties of the polymer are reported. Polymerized crystals are triclinic, space group P1 , a = 7.2144 Å, b = 7.2447 Å, c = 18.5936 Å, α = 104.49°, β = 96.631°, γ = 95.706°, Z = 2. The structure consists of 2-dimensional layers of polymer and inorganic CdCl₆ octahedra alternatively stacked in the third dimension. The cadmium ions can be separated from the polymer by a precipitation as insoluble CdS. After separation from the inorganic material the polymer is soluble in strong acids and bases and insoluble in neutral water. From viscosity measurements of alkaline solutions of the polymer, an average molar mass of 4 × 10⁴ g/mol can be deduced. The polymer selectively adsorbs divalent transition metal ions if suspended in an aqueous solution of transition metal salts. The structure of the resulting polymer–metal complexes is discussed.     

Crystal structure of polyisobutylene

The crystal structure of polyisobutylene was determined by x-ray analysis. The orthorhombic cell, with a = 6.88 Å, b = 11.91 Å, c (fiber axis) = 18.60 Å (space group: P2₁2₁2₁ ? D), contains two molecular chains each consisting of eight monomeric units in the fiber identity period. The chain conformation is essentially an (8/3) helix, but deviates appreciably from the exact (8/3) helix symmetry. The symmetry of the molecular chain is only a twofold screw axis in exact sense, and a crystallographic asymmetric unit consists of four monomeric units. The torsional angles are where M denotes the methyl group. The averaged skeletal C? CH₂? C and C? CM₂? C bond angles are 128° and 110°, respectively. The large C? CH₂? C bond angles may be due to steric respulsion between the adjacent methyl groups, giving intramolecular distances larger than 3.09 Å.     

Solid-state polymerization of a cyclic diacetylene

Large polymeric single crystals of a unique ring-bridged polymer have been produced by the solid-state polymerization of a cyclic diacetylene (o,o′-diacetylenyldiphenyl glutarate). These crystals are of high thermal stability, metallic in appearance with an asbestos-like texture, infusible, and insoluble. Single-crystal x-ray diffraction investigation indicates that the polymer is monoclinic (probable space group C2/c or Cc) with a unit cell containing four monomer units of dimensions α = 20.8 Å, b = 8.0 Å, c = 9.7 Å, and β = 106°. Infrared spectra eliminate the previously suggested possibility that the solid-state reactivity of the above monomer corresponds to either reaction of the carbonyl function with the acetylenic bond or the cleavage of the ester linkage. Diffraction, dichroism, and Raman spectral studies indicate instead that the reaction proceeds by 1,4-addition polymerization at the diacetylene group to produce a trans–trans polymer of structure where the curved lines represent the di-(o-phenyl)-glutarate linkages which are on opposite sides of the chain for adjacent monomer units.     

THE CRYSTAL STRUCTURES OF TWO IMINO-1,2,4- DITHIAZOLES FORMED BY THERMAL DECOMPOSITION OF 5-(DIALKYLAMINO)-3-(SUBSTITUTED IMINO)-1,2,4-DITHIAZOLES

Abstract

The thermal decomposition products of two substituted imino-1,2,4-dithiazoles have been studied by single crystal x-ray analysis. Both products crystallize in space group P2^1/c with four molecules per unit cell. The first product, obtained from 5-(dimethylamino)-3-(methylimino)-1,2,4-dithiazole has cell dimensions of a=9.922(8) Å, b=12.052(11) Å, c=13.358(12) Å and β=104.9(1)°. The molecule is made up of two planar segments related by an extremely large twist (?154°) about a C?N double bond. The results from this study have also contributed further information in the area of nonbonded interactions between ring and thione sulfur atoms. The second product, from 5-(dimethylamino)-3(phenylimino)-1,2,4-dithiazole was shown to be an ordered 1:1 complex of the starting material and one of its isomers. The cell dimensions are a=12.420(6) Å, b=8.840(9) Å, c=22.276(22) Å and β= 112.2(1)°. The different molecules are linked by an inter molecular NH… N hydrogen bond.     

Synthesis and Characterization of ASnOAsO4(A = K and Rb)

Crystals of two alkali-metal tin(IV) arsenates, KSnOAsO₄ and RbSnOAsO₄, were grown from a flux and structurally characterized by single-crystal X-ray diffraction. Crystal data: RSnOAsO₄, orthorhombic, Pna2₁ (No. 33), a = 13.406(3) Å, b = 6.678(1) Å, c = 10.921(2) Å, Z = 8, R = 0.037 for 1173 independent reflections with I > 2.5ó(l); RbSnOAsO₄, as above except a = 13.567(3) Å, b = 6.791( 1) Å, c = 10.891(2) Å, R = 0.035 for 1958 independent reflections. The two compounds are isostructural with the nonlinear optical material KTiOPO₄. The oxygen frameworks of both tin compounds approximate closely to a centrosymmetric arrangement, as indicated from the analysis of atomic coordinates. Second harmonics were generated in powdered RbSnOAsO₄ to confirm the absence of a center of symmetry in the structure.     

The Phase Diagram of the System [Ph4P]Br/BiBr3. Synthesis,Crystal Structure,Thermal Behaviour,and Vibrational Spectra of [Ph4P]3[Bi2Br9] · CH3COCH3 and two Modifications of [Ph4P]4[Bi6Br22]

The phase diagram of the system [Ph₄P]Br/BiBr₃ was investigated with the aid of DSC, TG and temperature dependent X‐ray powder diffraction measurements. By varying the reaction conditions, stoichiometry and crystallisation conditions of the reaction between BiBr₃ and [Ph₄P]Br four polynuclear bromobismuthates are formed. We report here the crystal structure of the solvation product [Ph₄P]₃[Bi₂Br₉] · CH₃COCH₃, which crystallises with monoclinic symmetry in the S. G. P2₁/n No. 14, a = 12.341(1), b = 32.005(3), c = 19.929(3) Å, β = 99.75(2)°, V = 7758(7) ų, Z = 4 and the crystal structures of two modifications of the compound [Ph₄P]₄[Bi₆Br₂₂]. The α‐form, crystallises with triclinic symmetry in the S. G. P1 No. 2, a = 13.507(4) Å, b = 14.434(4) Å, c = 17.709(5) Å, α = 81.34(2)°, β = 72.42(2)°, γ = 72.53(2)°, V = 3132.7(1) ų, Z = 2. The high‐temperature β‐form, crystallises with triclinic symmetry in the S. G. P1 No. 2, a = 13.893(4) Å, b = 14.267(3) Å, c = 16.580(3), α = 100.13(2)°, β = 96.56(2)°, γ = 110.01(2)°, V = 2985.5(1) ų, Z = 2. Lattice parameters of [Ph₄P]₄[Bi₈Br₂₈] are also given. The thermal behaviour of the compounds and in addition the vibrational spectra of [Ph₄P]₃[Bi₂Br₉] · CH₃COCH₃ are presented and discussed.     

The Synthesis and Crystal Structure of NpSe3

Neptunium triselenide, NpSe₃, was synthesized in high yield by the reaction of the elements in a Sb₂Se₃ flux at 1223 K. Its structure has been determined by single‐crystal X‐ray diffraction methods. Thecompound crystallizes with two formula units in space group C$\rm^{2}_{2h}$ –P2₁/mof the monoclinic system in the TiS₃ structure type with cell constants at 100 K of a = 5.592(3) Å, b = 4.002(2) Å, c = 9.422(5) Å,β = 97.40(1) °. The asymmetric unit comprises one neptunium and three selenium atoms, each with site symmetry m. Np–Se interatomic distances range from 2.859(2) to 2.927(3) Å; the Se–Se bond length of 2.340(3) Å is typical of a single bond. The compound may thus be charge‐balanced and formulated as Np⁴⁺Se^2–Se₂^2–.     

Two Novel Cobalt(II) Coordination Polymers Based on the Herbicide Glyphosate as a Building Block and their Magnetic Properties

The hydrothermal reaction of glyphosate and Co(Ac)₂·4H₂O in the presence of water and ethanol at different temperatures affords two novel cobalt coordination polymers: C₁₂H₃₀N₄O₂₀P₄Co ( 1 ) and C₃H₁₀NO₇P₁Co ( 2 ). Both structures were determined by single crystal X‐ray diffraction. The coordination polymer of 1 is a one‐dimensional chain polymer with the crystal data: , a = 5.5010(7), b = 10.983(2), c = 11.381(2) Å, α = 69.848(2), β = 86.645(2)°, γ = 79.788(2), V = 634.6(2) ų, Z = 1, R1 = 0.0548, wR2 = 0.1557, whereas the coordination polymer of 2 is a two‐dimensional layered polymer with the crystal data: , a = 8.9669(7), b = 7.3670(5), c = 12.7577(9) Å, β = 101.433(2)°, V = 826.04(10) ų Z = 4, R1 = 0.0325, wR2 = 0.1125. The glyphosate ligand exhibits different coordination behaviors in these two coordination polymers. Research on magnetic behavior revealed an antiferromagnetic coupling interaction between the Co²⁺ ions in both compounds.     

[CoIICuI2(Im)4];∞: A Layered Bimetallic Imidazolate Polymer,the First Hybridized Cobalt(II) Imidazolate

A 2D grid‐shaped bimetallic imidazolate polymer [Co^IICu^I₂(Im)₄]_;∞ ( 1 ) was solvothermally synthesized and characterized with single crystal X‐ray analysis: tetragonal space group P 2₁/c (No.114), a = b = 10.9513(15) Å, c = 6.3063(13) Å, V = 756.3(2) ų. This is the first cobalt(II) imidazolate polymer hybridized with other transition metals.     

Synthesis of two novel cobalt complexes and their crystal structures

Two new cobalt complexes were successfully synthesized from the reaction of binaphthyl Schiff base 2 with Co(OAc)₂ in the presence of sodium methoxide at 80 °C for 24 h and Co(acac)₃ in toluene under reflux. Their unique crystal structures are unambiguously disclosed by X‐ray analysis. Complex 3 is triclinic, space group P1 , unit cell dimensions a = 10.742(2) Å, b = 11.153(2) Å, c = 12.715 Å, α = 79.865(3) °, β = 76.053 °, γ = 72.532(4) °, volume 1401.3(5) ų, Z = 2. Complex 4 is triclinic, space group P1 , unit cell dimensions a = 10.801(2) Å, b = 12.554(3) Å, c = 15.219(3) Å, α = 105.672(4) °, β = 103.048 °, γ = 104.594(4) °, volume 1824.8(7) ų, Z = 2, calculated density 1.428 Mg m⁻³. Copyright © 2003 John Wiley & Sons, Ltd.     

The crystal structure of poly(tetramethylene terephthalate)

The unit cell of poly(tetramethylene terephthalate) is triclinic with parameters a = 5.96 Å, b = 4.83 Å, c (fiber axis) = 11.62 Å, α = 115.2. β = 99.9, and γ = 111.3°; space group P1 , calculated crystalline density 1.41 g/cc. The plane of the benzene ring is found to be inclined by about 15° from the fiber axis, contributing to a shortening of the fiber period as compared to the period expected on the basis of analogy with other members of the terephthalate ester series. The remaining shortening of the fiber period occurs in the ? O? °CH₂? °CH₂? segment of the chain. No abnormally short distances among neighboring chain atoms were observed. A typical texture pattern was found in specimens of this polymer that were cold rolled and subsequently annealed. In this texture the c axis of the unit cell is highly oriented in the rolling direction; the a and b axes of the unit cell are oriented preferentially so that the terephthalate residue lies as close as possible to the plane of rolling.     

Two new long-period structures related to β-alumina

Two new ordered forms of “β-alumina” with rhombohedral symmetry have been discovered and their structures deduced from one-dimensional electron microscope images of thick crystals. Referred to a hexagonal cell, their lattice parameters are a = 5.59Å, c = 169.5Å and a = 5.59Å, c = 339Å. A symbolism for describing structures related to that of β-alumina is proposed.