Isotactic poly(pentene-1): Polymorphism of form I

The polymorphism of isotactic poly(pentene-1) form I was studied by x-ray diffraction. Upon quenching from the melt at a temperature below 25°C, the films crystallized in a stable monoclinic form, which we have designated as form I (a = 22.4 ± 0.2 Å, b = 6.49 ± 0.05 Å, c = 21.2 ± 0.2 Å, β = 91 ± 1°). For higher quenching temperatures, a metastable form, form I′, appeared, which transforms to the normal modification upon aging (monoclinic, with: a = 24.3 ± 0.2 Å, b = 6.50 ± 0.05 Å, c = 19.3 ± 0.2 Å, β = 96 ± 2°). Both modifications have a 3₁ helical conformation. Limited changes in the packing mode could explain this polymorphism.     

Crystal and molecular structure of cis- and trans-2,4-dihydroxy-2,4-dimethylcyclohexanetrans-1-acetic acid γ-lactone

During the transformation process of limonene to tetrahydrofuran derivatives, the title compounds (±)-( 4 ) have been obtained as crystalline products and subjected to X-ray analysis. The crystals of trans-( 4 ) are orthorhombic, space group P2₁2₁2₁, with the lattice constants a = 7.0445(5) Å, b = 10.0908(4) Å, c = 14.0309(6) Å; the absolute configuration at atoms C1, C2, and C4 is R_c1, S_c2, and R_c4, respectively. The isomeric form cis-( 4 ) crystallizes in the monoclinic system, space group P2₁, with the following unit-cell parameters: a = 10.8275(4) Å, b = 8.6994(5) Å, c = 16.4722(6) Å, β = 106.515(3)°. The asymmetric part of the unit cell of cis-( 4 ) contains three independent molecules. Each of these three molecules has the identical absolute configuration at all centers of chirality: S_c1, S_c2, and R_c4. © John Wiley & Sons, Inc.     

Solid-state polymerization of diacetylene: 1,11,13,23-tetracosatetrayne

The solid-state polymerization of a diacetylene, 1,11,13,23-tetracosatetrayne, was studied using x-ray powder diffraction and electron diffraction. It is shown that the material exhibits polymorphism. Thermochromic transitions, which are generally observed for diacetylenes, are related to the particular crystalline phase using x-ray powder diffraction. The unit cell dimensions and space group of one polymorph were determined by electron diffraction analysis: a = 20.83 Å, b = 4.84 Å, c = 10.08 Å, β = 92.4°, space group: P2₁/n. © 1995 John Wiley & Sons, Inc.     

Unit cell dimensions of isotactic polyvinylcyclopropane

The unit cell dimensions of isotactic polyvinylcyclopropane were determined, based on crystalline, oriented fiber and film samples. Two structures were found: (1) a hexagonal structure with a = 13.6 Å, c = 6.48 Å, 3₁ helix, space group P3₁ and P3₂, ρ(calc) = 0.9805 g/cm³, ρ(obs) = 0.975 g/cm³; (2) a tetragonal structure with a = 15.21 Å, c = 20.85 Å, 10₃ helix, space group I4 , ρ(calc) = 0.926 g/cm³.     

Difluorotetrakis(2‐oxypyridine)dirhenium(III) – Preparation,Crystallographic Structure,and Electrochemical Properties

The solid‐state‐melt reaction of (NH₄)₂[Re₂F₈] · 2H₂O with 2‐hydroxypyridine (2‐HOpy) produced dark‐red Re₂(2‐Opy)₄F₂ ( 1 ). This air‐stable compound was obtained in crystalline form as 1· CHCl₃. It was characterized in the solid state by single‐crystal X‐ray diffraction and in solution by UV/Vis spectroscopy and cyclic voltammetry. 1· CHCl₃ forms triclinic crystals with α = 8.3254(5) Å, b = 8.5563(5) Å, c = 11.6784(8) Å, α = 82.723(3)°, β = 75.769(3) °, γ = 64.407(2) °. The Re–Re and Re–F distances were 2.2091(7) and 2.115(6) Å, respectively. The molecule is isostructural with the corresponding chloro derivative.     

The structure of (dichloro) (DI-μ-acetato)(bis-triphenyl phosphine) dimolybdenum(II)

The title compound was obtained in crystalline form suitable for X-ray structure determination. It forms crystals in the monoclinic space group P2₁/c with two centrosymmetric molecules in a unit cell of dimensions, a = 10.888(1) Å, b = 10.182(2) Å, c = 17.929(4) Å, β = 104.33(1)°. The central Mo₂Cl₂(O₂C)₂P₂ core has effectively C_2h-symmetry with the following principal dimensions: MoMo = 2.091(1) Å, MoCl = 2.405 Å, MoP = 2.566(2) Å, MoO(av.) = 2.103[4] Å, MoMoP = 104.38(7)°, and MoMoCl = 116.23(8)°.     

THE CRYSTAL,MOLECULAR STRUCTURE AND LIGAND BONDING IN TETRAKIS (N,N′-DIMETHYLTHIOUREA) NICKEL (II) BROMIDE DIHYDRATE

Abstract

The crystal structure of tetrakis(N,N′-dimethylthiourea)nickel(II) bromide dihydrate has been determined by three-dimensional x-ray diffraction from 1916 counter-data reflections collected at room temperature.

The structure consists of Ni[SC(NH)₂(CH₃)₂]²⁺ ₄ molecular ions, Br^? ions and waters of hydration. The nickel is located on a center of symmetry and is coordinated to four sulfur atoms in a square planar configuration. The waters of hydration and the bromide ions are involved in hydrogen bonding to the N,N′-dimethylthiourea (dmtu) groups. The orientation of the dmtu groups is such that two bond through the sulfur sp² orbital and the others bond through the π-orbitals of the dmtu group. The Ni-S distances are 2.204 ± 0.002 Å and 2.230 ± 0.002 Å, and the Ni-S-C angles are 106.2 ± 0.2Å and 110.3 ± 0.3°. The dmtu groups are planar except for methyl hydrogens.

The crystals are monoclinic, P2₁/a with a = 13.424 ± 0.002 Å, b = 12.321 ± 0.005 Å, c = 8.460 ± 0.008 Å β = 107.07 ± 0.05°, ρ₀ = 1.67 g cm^?3, ρ_c = 1.66 g cm^?3 and Z = 2. The structure was refined by full-matrix least-squares to a conventional R of 0.0466.     

Electron diffraction study on the molecular structure of methane sulphonyl fluoride

The molecular structure of methane sulphonyl fluoride in the vapour state was studied by electron diffraction. Assuming a value of 2.480A?for the distance between the oxygen atoms from a microwave determination, the following geometrical parameters (r_a structure) have been obtained: r(C-H) = 1.093±0.010Å, r(S-O) = 1.410±0.003Å, r(S-F) = 1.561 ±0.004Å, r(S-C) = 1.759±0.006Å, ∠F-S-C = 98.2±1.5°, ∠-S-F = 106.2±0.4°, ∠-O-S-O = 123.1 ±1.5° and ∠H-C-H = 112.9±1.9°. All the observed variations in the molecular geometries of (CH₃)₂SO₂, CH₃SO₂Cl, CH₃SO₂F and SO₂F₂ may be accounted for by the valence shell electron pair repulsion theory. It is particularly advantageous to combine electron diffraction and microwave data in studying sulphone molecular geometries.     

Gas phase structures of the isomers of benzene,V. (dewar-benzene) by electron diffraction

The parent hydrocarbon, Dewar-benzene, has been studied by gas phase electron diffraction analysis. Assignment of C_2v symmetry gave excellent agreement between the experimental and theoretical data. The structural parameters obtained were in good agreement with previous electron diffraction structures of substituted derivatives of the Dewar-benzene series. The structural parameters with error limits are (cf. Fig. 2): r(C₃-C₆) = 1.574 ± 0.005 Å r(C₂-C₃) = 1.524 ± 0.002 Å, r(C₁-C₂) = 1.345 ± 0.001 Å, r(C₃-C₉) = 1.134 ± 0.004 Å, r(C₁-C₇) = 1.124 ± 0.004 Å, ∠C₁C₆C₅ = 116.7 ± 0.6°, ∠C₃C₆C₁ = 85.7 ± 0.2°, ∠C₆C₃C₉ = 108.0 ± 3.0°, ∠C₃C₂C₈ = 126.7 ± 2.5°, and α = 117.25 ± 0.6°. The angle γ was assumed to be 0°.     

The molecular structures of mono-substituted cl-cyclohexene by gas-phase electron diffraction

The molecular structures of mono-substituted chlorocyclohexene are determined by gas-phase electron diffraction. The structural parameters are obtained by applying leastsquares analysis to the molecular scattering intensities. The bond distances (r_g) and bond angles are: (1) 1-Cl-cyclohexene: C₁C₂ = 1.336 ± 0.006 Å. C₂-C₃ = 1.500 ± 0.009 Å, C₃-C₄ = 1.533 ± 0.010 Å, C₄-C₅ = 1.537 Å, C₅-C₆ = 1.527 ± 0.010 Å, C₁-C₆ = 1.504 ± 0.009 Å. C-Cl = 1.747 ± 0.005 Å, C-H_av = 1.138 ± 0.010 Å, ∠Cl-cc = 126.3 ± 0.5°, ∠C₆C₁C₂ = 123.9 ± 0.8°. ∠C₁C₂C₃= 124.6 ± 0.8°, ∠C₄C₃C₂ = 111.8 ± 1.2° and ∠-C₅C₆C₁ = 111.3 ± 1.1°; (2) 3-Cl-cyclohexene: C₁=C₂ = 1.336 Å, C₂-C₃ = 1.501 ± 0.010 Å, C₃-C₄ = 1.513 ± 0.008 Å, C₄-C₅ = 1.542 Å, C₅-C₆, = 1.516 ± 0.007 Å, C₁-C₆ = 1.505 ± 0.006 Å, C-C1 = 1.801 ± 0.005 Å, C-H_av = 1.120 ± 0.008 Å, ∠C₆C₁C₂ = 123.2 ± 1.0°, ∠C₁C₂C₃ = 124.1 ± 1.7°, ∠C₅C₆C₁ = 113.0 ± 1.3°, ∠C₂C₃C₄ = 112.5 ± 1.5° ∠ClC₃C₂ = 110.3 ± 0.8°, ∠H-C=C = 123.0 ± 3.0° and ǒH-C-C = 109.5 ± 2.0°, with a mixture of 55% axial and 45% equatorial conformers; (3) 4-Cl-cyclohexene: C₁=C₂ = 1.336 Å, C₂-C₃ = 1.507 ± 0.007 Å, C₃-C₄ = 1.516 ± 0.008 Å, C₄-C₅ = 1.544 Å, C₅-C₆ = 1.523 ± 0.010 Å, C₁- C₆ = 1-507 Å, C-Cl = 1.799 ± 0.005 Å, C-H_av = 1.116 ± 0.005 Å, ∠C₆C₁C₂ = 123.3 ± 1.5°, ∠C₅C₆C₁ = 113.0 ± 1.0°, ∠C₂C₃C₄ = 112.3 ± 1.0°, ∠ClC₄C₃ = 110.2 ± 2.0°, ∠H-CC = 117.1 ± 4.5° and ∠H-C-C = 109.5 ± 1.0°, with a mixture of 45% axial and 55% equatorial conformers.     

Molecular structure of 1,2,4-triazole

The molecular structure of 1,2,4-triazole has been determined by gas phase electron diffraction. The intemuclear distances and bond angles were obtained by applying a least-squares analysis to the experimental intensity. The bond distances (r_g) and bond angles were N₁-N₂ = 1.380 ± 0.010 Å, N₂C₃ = 1.329 ± 0.009 Å, C₃-N₄ = 1.348 ± 0.009 Å, N₁-C₅ = 1.377 ± 0.004 Å, N₄C₅ = 1.305 Å (calculated value). N-H = 0.990 Å, C-H = 1.054 Å, ∠N₁N₂C₃ = 102.7± 0.5°, ∠N₂C₃N₄ = 113.8 ± 1.3°, ∠N₂N₁C₅ = 108.9 ± 0.8°, ∠H₁N₁N₂ = 110.9°, ∠H₂C₃N₄ = 119.2°, ∠H₃C₅N₁ = 131.0°, ∠C₃N₄C₅ = 105.7° (calculated value) and ∠N₄C₅N₁ = 108.7° (calculated value).     

A new type of liquid crystal involving hydrogen bonding: single crystal X-ray structure characterization and properties of the liquid crystal

A new liquid crystal involving hydrogen bonding between 4-hexyloxybenzoic acid and 4-octyloxylphenylethynylpyridine has been investigated by DSC, polarizing optical microscopy and X-ray diffraction. The mesogen shows a nematic phase and an unknown liquid crystalline phase. The liquid crystal crystallizes with a triclinic space group P-1 with the parameters: a = 8.879(2)Å, b = 10.137(2)Å, c = 17.629(4)Å; α = 104.16(3)°, β = 95.47(3)°, γ = 101.48(3)°; V = 1490.3(6)ų; Z = 2; F(000) = 572; μ = 0.076 mm^?1; λ(MoK_α) = 0.71073 Å; final R ₁ = 0.0435. The complex is formed by strong intermolecular hydrogen bonding.     

Synthesis,Crystal Structure and Properties of [Mn(hdpa)2(N(CN)2)2] and [Co(hdpa)2(N(CN)2)2] (hdpa = 2, 2'‐Dipyridylamine)

Two new transition metal(II) complexes [M(hdpa)₂(N(CN)₂)₂] (M = Mn ( 1 ), Co ( 2 ); hdpa = 2, 2'‐dipyridylamine) have been prepared and characterized structurally and magnetically. Both compounds crystallize in the monoclinic space group C2/c. 1 and 2 are isotypic with the unit cell parameters a = 8.634(9), b = 13.541(14), c = 21.99(2) Å, β = 94.806(18)°, and V = 2562(5) ų for 1 , a = 8.617(3) Å, b = 13.629(5)Å, c = 21.598(8)Å, β = 94.593(6)°, and V = 2528.4(15)ų for 2 , and Z = 4 for both. According to X‐ray crystallographic studies, each metal(II) ion was six‐coordinated with four nitrogen atoms from two bidentate hdpa ligand and two nitrogen atoms from two N(CN)^— anions to form slightly distorted octahedrons. Adjacent complex molecules are connected by hydrogen bonds or π···π interactions to form three‐dimensional network. The IR and UV spectroscopy were measured and the magnetic behaviors were investigated.     

The reaction of sulfur with dilithio compounds. The syntheses and structures of phenanthro [1, 10-cd]-1,2-dithiole and phenanthro[4,5-cde] [1,2]dithiin

The sequential reaction of selected polycyclic aromatic hydrocarbons with butyllithium/TMEDA/hexane and sulfur allows preparation of ring-fused dithiins, dithioles, and thiophenes. In this manner, phenanthrene has been converted to phenanthro[4,5-cde][1,2]dithiin and phenanthro[1,10cd]-1,2-dithiole. Yellow crystals of the dithiin form in C2/c (#15) space group with Z = 4, a = 13.537(3) Å, b = 8.933(2) Å, c = 9.601(4) Å, and β = 116.19 (2)°; while orange crystals of the dithiole form in P2₁2₁2₁ (#19) space group with Z = 4, a = 4.1507(5) Å, b = 14.436(3) Å, and c = 16.972(3) Å. Full structures have been determined for both compounds.     

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.     

Na2Ge3P3 and Na5Ge7P5 Comprising Heteroatomic Polyanions Mimicking the Structure of Fibrous Red Phosphorus

Recently lithium phosphidogermanates were discovered as fast lithium ion conductors for potential usage as solid electrolytes in all solid-state batteries. In this context we also studied sodium phosphidogermanates since sodium ion conductors are of equal interest. Na₂Ge₃P₃ and Na₅Ge₇P₅ both crystallize in the monoclinic space group C2/m with unit cell parameters of a = 17.639(4) Å, b = 3.6176(7) Å, c = 11.354(2) Å, β = 92.74(3)° and a = 16.168(5) Å, b = 3.6776(7) Å, c = 12.924(4) Å, β = 91.30(3)°, respectively. Both show linearly condensed 9-atom cages of four Ge / five P and five Ge / four P atoms, respectively. These cages contain Ge–Ge bonds and form one-dimensional tubes by sharing three atoms. The parallel tubes are paired through further Ge–Ge bonds. Both structures are closely related to the one of the fibrous type of crystalline red phosphorus. A comparison with other compounds such as NaGe₃P₃ and GeP reveals recurring structural motifs with a broad variety of connection patterns. According to the general formula Na_4+xGe_6+xP_6–x with x = 0 and 1, the two novel structures hint for the possibility of a variable Na content which might allow Na ion mobility.     

Crystal and molecular structure of triphenyl 4,4,6-Trimetliyl-1-oxa-3-azaeyeiohex-2-enylcarbenyl phosphonium chloride

The structure of the title compound has been determined by a single crystal, x-ray diffraction study. The compound crystallizes in a monoclinic unit cell of P2₁/c symmetry and dimensions, a = 9.832 ± .001 Å, b = 15.398 ± .001 Å, c = 19.762 ± .002 Å, and β= 123.06 ± .01 ° with four molecules per unit cell. The 1633 statistically significant reflections (from a total of 2743 out to 20 = 100°) refined to a final value of R = 0.05₃. The molecule itself consists of a chloride ionically bonded to a cation containing a tetrahedral phosphorus bound to three phenyl rings and a fourth oxazine ring. It is the latter ring which displays extensive derealization as discussed in the paper.     

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.     

1,4,7-Trithiacyclononane as a Tridentate Ligand for Complexation of Heavy-Metal Ions: Synthesis and Complexation Studies of Mesocyclic and Macrocyclic Polythioethers IV

Bis octahedral complexes of 1,4,7-trithiacyclononane (9-ane-S₃) with Group 12 metal ions Zn(II), Cd(II), and Hg(II), as well as Pb(II), have been prepared. Two equivalents of 9-ane-S₃ react with Zn(BF₄)₂·6H₂O, Cd(ClO₄)₂·6H₂O, Hg(ClO₄)₂·3H₂O, and Pb(ClO₄)₂. 3H₂O, respectively, to give stable crystalline complexes of the formula [M(9-ane-S₃)₂]²+ 2X⁻. Single-crystal X-ray structures of the zinc and mercury complexes have been determined. The zinc complex crystallizes in the orthorhombic space group Pbca with four molecules per unit cell (a = 9.219(3) Å, b = 15.400(5) Å, and c = 19.965(10)Å; R = 7.6%) whereas the mercury complex crystallizes in the monoclinic space group P2₁/c with two molecules per unit cell (a = 10.400(3) Å, b = 15.190(4) Å, c = 9.533(3) Å, and p = 99.09(3)°; R = 5.2%). In each structure, the metal atom is located on a crystallographic center of inversion and is octahedrally surrounded by six sulfur atoms provided by the two facially coordinating tridentate ligands. Reaction of 9-ane-S₃ with RuCl₃·xH₂O displaces chloride ions with concomitant reduction of Ru(III) to Ru(II), giving the octahedral thioether complex, [Ru(9-ane-S₃)₂]Cl₂·4H₂O. Reaction of the ligand with RhCl₃, on the other hand, gives (9-ane-S₃)RhCl₃. A single-crystal X-ray structure determination has been done on the Ru(II) complex (triclinic space group P 1 ̅; a = 7.652(1) Å, b = 8.946(1) Å, c = 9.042(1) Å, α = 93.43(1)°, β = 103.43(1)°, and γ = 107.79(1)°; R = 2.8%) and this complex is also octahedral with the metal center at an inversion center.     

Molecular and Low‐dimensional Coordination Compounds of Copper(II) and 3, 5‐Dimethylpyrazole — Synthesis,Crystal Structure,and Properties

Three 3, 5‐dimethylpyrazole (pz*) copper(II) complexes, [Cu(pz*)₄(H₂O)](ClO₄)₂ ( 1 ), [Cu(pz*)₂(NCS)₂]·H₂O ( 2 ), and [Cu(pz*)₂(OOCCH=CHCOO)(H₂O)]·1.5H₂O ( 3 ), have been synthesized and characterized with single crystal X‐ray structure analysis. 1 crystallizes in the tetragonal space group, 14/m, with a = 14.027 (3) Å, c = 16.301 (5) Å, and Z = 4. 2 crystallizes in the monoclinic space group, P2₁/c, with a = 8.008 (3) Å, b = 27.139 (9) Å, c = 8.934 (3) Å, β = 106.345 (6)°, and Z = 4. 3 crystallizes in the triclinic space group, P1¯, with a = 7.291 (9) Å, b = 10.891 (13) Å, c = 11.822 (14) Å, α = 80.90 (2)°, β = 79.73(2)°, γ = 70.60(2)°, and Z = 2. In 1 , one water molecule and four pz* ligands are coordinated to Cu^II. Two [Cu(pz*)₄(H₂O)]²⁺ units are connected to ClO₄^— via hydrogen bonds. One lattice water molecule is found in the unit cell of 2 , which forms an one‐dimensional chain via intermolecular hydrogen bonds with the N‐H atom of pz*. In 3 , the oxygen atom of the coordinated water molecule is connected with two C=O groups of two neighbouring maleic acid molecules to form a linear parallelogram structure. Another C=O group of maleic acid forms a hydrogen bond with the N‐H atom of pz* to create a two‐dimensional structure. The spectroscopic and bond properties are also discussed.