The molecular and crystal structure of a polar mesogen 4-cyanobiphenyl-4′-hexylbiphenyl carboxylate

The crystal structure of the compound 4-cyanobiphenyl-4′-hexylbiphenyl carboxylate (6CBB), which exhibits both monolayer smectic A and nematic phases, has been determined by direct methods using single crystal X-ray diffraction data. The structure is triclinic with the space group P-1 and Z=2. The unit cell parameters are a=9.3511(7)?Å, b=11.2456(7)?Å, c=13.1417(6)?Å, α=85.872(4)°, β=76.258(5)° and γ=70.697(5)°. The molecule is found to be slightly bow-shaped although the alkyl chain is in all-trans conformation. The phenyl rings in 6CBB are non-coplanar. The packing of the molecules in the crystalline state is found to be a precursor to the smectic A phase structure. Comparison of crystal structures and packing of the four-ring 6CBB with those of the two-ring nCB or nOCB compounds has been made to explain the observed phase behaviour.     

The synthesis and crystal structure of α-perthionaphthoatopyridinecopper(I) dimer Cu2(α-C10H7CSS2)2(Py)2

The title compound has been synthesized by the reaction of α-dithionaphthoic acid with CuCl₂ in pyridine or by recrystallizing Cu₄(α-C₁₀H₇CSS₂)₄ ? 1/2CS₂ in a mixture of pyridine and alcohol. The structure of the title compound is determined by a single-crystal X-ray diffraction analysis. The crystal belongs to triclinic space group with unit cell parameters: a=7.085(2)Å, b= 8.672(3)Å and c=13.598(5)Å; a=92.40(3)°, β=102.59(4)° and γ=105.67(4)°; V=780.6Ų; Z=1. The structure was refined to R=0.058 for 2390 reflections. The molecule of the title compound sits on a center of symmetry. The shorter Cu—Cu bond length (2.606Å) shows considerable interaction between copper atoms. If the Cu—Cu interaction is ignored, the neighbouring S and N atoms are coordinated to copper atom in a configuration of distorted tetrahedron.     

Open metallocenes XI. A pentadienyl compound of heavier rare earth element [2,4-(CH3)2-η5-C5H5]3Tb·1/2THF

The reaction of TbCl₃ with K[2,4-(CH₃)₂ C₅H₅] at 0°C in THF followed by crystallization at ?90°C led to a pale yellow hexagonal prismatic crystalline product [2,4-[CH₃)₂-η⁵-C₅H₅]₃-Tb·1/ 2THF , which is highly sensitive to air and water and rapidly efflorescent at ambient temperature. The single crystal X-ray diffraction data of the compound have been collected at low temperature (-60°C) and the crystal structure has been solved by heavy atom method. It belongs to triclinic system, space group P1 with lattice parameters α=8.477 Å , b=12.583 Å , c=12.858 Å , α=118.08°, β=91.38°, γ=108.75°, V=1120.36 ų and Z=2. Least-squares refinement converged to a final value R=0.043. The compound possesses an idealized C_3h symmetry with three 2,4dimethylpentadienyl ligands bound to the central terbium atom in a pentahapto mode (η⁵). Each unit cell contains two molecules of [2,4-(CH₃)₂-η⁵-C₅H₅]₃Tb and one molecule of solvent THF, of which the role in the lattice has been discussed in detail.     

Über Chalkogenolate. 117 [1]. Untersuchungen über Guanidinodithioformiate 4. Kristall- und Molekülstruktur der Guanidinodithioameisensäure

On Chalcogenolates. 117. Studies on Guanidinodithioformates. 4. Crystal and Molecular Structure of Guanidinodithioformic Acid Guanidinodithioformic acid crystallizes with Z = 4 in the monoclinic space group P2₁ with cell dimensions a = 4.204(3) Å, b = 10.422(5) Å, c = 12.491(5) Å, β = 93.9(3)°. The crystal and molecular structure has been determined from single crystal X-ray data at 20°C and refined to a conventional R of 0.0242. The asymmetric part of the unit cell contains two molecules in the dipolar form with different conformation. The molecules have delocated double-bonds and are linked together by N? H···S hydrogen bridges.     

A comparative study of mesogenic structures. The crystal structures of bis[(4-butoxycarbonyl)-phenyl]terephthalate and bis[(4-vaIeroyloxy)-phenyl]terephthalate

Abstract

Smectogenic bis[(4-butoxycarbonyl)-phenyl]terephthalate (B-A) and Hematogenic bis[(4-valeroyloxy)-phenyl]terephthalate (V-A) have been synthesized and their crystal and molecular structure have been determined, at room temperature, by direct methods. Crystals of B-A are triclinic, space group P1, a = 5·914(1) Å, b = 8·532(1)Å, c = 13·647(2)Å, α=102·07(1)°, β = 92·73(2)°, γ = 73·21(2)° with one molecule per unit cell. Crystals of V-A are monoclinic, space group P21/c, a = 32·318(5)Å, b = 5·350(3)Å, c = 7·987(2)Å, β = 92·84(2)° with two molecules per unit cell. The structures were refined by the full matrix least squares method, to R = 0·050 for B-A and R = 0·071 for V-A. Molecules of B-A and V-A are centrosymmetric (point group Ci) and show some differences in the structure of the phenyl terephthalate moiety, which are probably due to the different electron withdrawing effects of the terminal substituents linked to the phenyl rings. The crystal packing of the two compounds is different. Molecules of V-A are packed in layers with their long molecular axes normal to the layer surface, while in B-A molecular layers are formed in which the long molecular axes are highly tilted with respect to the layer normal.     

A Revised Structure Model for the UCl6 Structure Type,Novel Modifications of UCl6 and UBr5, and a Comment on the Modifications of Protactinium Pentabromides

The redetermination of the crystal structure of trigonal UCl₆, which is the eponym for the UCl₆ structure type, showed that certain atomic coordinates had been incorrectly reported. This led to noticeably different U−Cl distances within the octahedral UCl₆ molecule (2.41 and 2.51 Å). Within the revised structure model presented here, which is based on single crystal data as well as quantum chemical calculations, all U−Cl distances are essentially equal within standard uncertainty (2.431(5), 2.437(5), and 2.439(6) Å). This room temperature modification, called rt-UCl₆, crystallizes in the trigonal space group P m1, No. 164, hP21, with a=10.907(2), c=5.9883(12) Å, V=616.9(2) ų, Z=3 at T=253 K. A new low-temperature (lt) modification of UCl₆ is also presented that was obtained by cooling a single crystal of rt-UCl_6. The phase change occurs between 150 and 175 K. lt-UCl₆ crystallizes isotypic to a low-temperature modification of SF₆ in the monoclinic crystal system, space group C2/m, No. 12, mS42, with a=17.847(4), b=10.8347(18), c=6.2670(17) Å, β=96.68(2)°, V=1203.6(5) ų, Z=6 at 100 K. The Cl anions form a close-packed structure corresponding to the α-Sm type with uranium atoms in the octahedral voids. During the synthesis of UBr₅ a new modification was obtained that crystallizes in the triclinic crystal system, space group P , No. 2, aP36, with a=10.4021(6), b=11.1620(6), c=12.2942(7) Å, α=68.3340(10)°, β=69.6410(10)° and γ=89.5290(10)°, V=1231.84(12) ų, Z=3 at T=100 K. In this structure the UBr₅ units are dimerized to U₂Br₁₀ molecules. The Br anions also form a close-packed structure of the α-Sm type with adjacent uranium atoms in the octahedral voids. Comparisons of the crystal structures of the compounds MX₅ (M=Pa, U; X=Cl, Br) show that the crystal structure of monoclinic α-PaBr₅ is probably not correct.     

Cobalt(III) Complex [CoL3] Derived from an Asymmetric Bidentate Schiff Base Ligand L (L=(5‐Bromo‐2‐hydroxybenzyl‐2‐furylmethyl)‐imine): Synthesis,Characterization and Crystal Structure

Cobalt(III) complex [CoL₃], where L=(5‐bromo‐2‐hydroxybenzyl‐2‐furylmethyl)imine, has been synthesized by reacting cobalt(II) nitrate with L. The complex has been characterized by elemental analysis and FT‐IR spectroscopy. The crystal structure of [CoL₃] was determined by X‐ray crystallography from single crystal data. It crystallizes in the triclinic space group$ P {\bar 1} $ with unit cell parameters:a=9.6644(10) Å,b=11.5657(11) Å,c=16.5809(17) Å,α=102.833(4)°,β=102.999(3)°,γ=105.480(3)°,V=1659.9(3) ųandZ=2. Thermal decomposition of [CoL₃] was studied by thermogravimetry in order to evaluate its thermal stability and thermal decomposition pathways.     

Crystal Structure of 4-Trimethyltin-quinuclidinium Perchlorate

The crystal structure of 4-trimethyltin-quinuclidinium perchlorate has been determined by direct methods and refined by least squares techniques. Crystals of C₁₀H₂₂ClNO₄Sn are monoclinic, space group I2/c with lattice parameters a = 29.445 (13), b = 18.400(8), c = 11.300(5) Å, β = 95.82(5)°, V = 6090.65ų, and two independent molecules (Z = 16), Interatomic distances are compared with those of known structures of quinuclidinium chloride and 4-haloquinuclidinium chlorides and perchlorates.     

Synthese,Kristallstruktur und thermische Entwässerung von CsMnF4 · 2H2O

Synthesis, crystal structure and thermal dehydration of CsMnF₄ · 2H₂O The preparation of a new fluoromanganate (III)-complex CsMnF₄ · 2H₂O is reported. It crystallizes in the monoclinic space group C2 with a = 11.891(2) Å, b = 6.589(1) Å, c = 10.558(1) Å, β = 131.46(1)° and Z = 4. The crystal structure has been solved from diffractometer data by heavy-atom methods and refined to a conventional R-value of 1.8% (including the contributions of three hydrogen atoms in measured and one in calculated positions). The structure is characterized by isolated, tetragonally distorted [MnF₄(OH₂)₂]-octahedra with Mn-F-distances from 1.801(8) Å to 1.870(7) Å and Mn-O-distances of 2.146(6) Å and 2.268(6) Å. Cesium exhibits an irregular 10-coordination by 8 F-atoms and 2 O-atoms (mean values for the two independent cesium ions: Cs-F = 3.17 Å and 3.21 Å, Cs-O = 3.32 Å and 3.29 Å). The [MnF₄(OH₂)₂]-octahedra are connected to six neighbouring octahedra by hydrogen bonding. The dehydration of the complex has been studied by thermoanalytical methods and power x-ray-diffractometry. The unit cell of the dehydrated compound, CsMnF₄, is tetragonal with a = 7.936(1) Å and c = 6.341(1) Å. A close relationship to the structure of CsFeF₄, which is a superstructure variant of the T1A1F₄-type[6], is indicated by the similarity of the corresponding unit cells and preliminary structure factor calculations. A proposition for the crystal structure of CsMnF₄ is developed on the basis of (2 + 2 + 2)-orthorhombic distorted MnF₆-octahedra.     

Crystal Structure of the [(C5H4BMe2)2Fe]‐4,4′‐bipyridine Polymer from High Resolution X‐Ray Powder Diffraction

The crystal structure of [(C₅H₄BMe₂)₂Fe]‐4,4′‐bipyridine [ 2 · bipy]_n has been determined by the method of simulated annealing from high resolution X‐ray powder diffraction at room temperature. The compound is of interest, because it proves that highly ordered organometallic macromolecules can be formed in the solid state via the self‐assembly of N–B‐donor‐acceptor bonds. [ 2 · bipy]_n crystallizes in the triclinic space group, P 1, Z = 2, with unit cell parameters of a = 8.3366(2) Å, b = 11.4378(3) Å, c = 12.6740(5) Å, α = 112.065(2)°, β = 108.979(1)°, γ = 90.551(2)°, and V = 1047.06(6) ų. For the structure solution of [ 2 · bipy]_n 11 degrees of freedom (3 translational, 3 orientational, 5 torsion angles) were determined within several hours, demonstrating that the crystal packing and the molecular conformation of medium sized (< 50 non‐hydrogen atoms) coordination compounds can nowadays be solved routinely from high resolution powder diffraction data.     

PM3 semiempirical study and its comparison with X-ray crystal structure of 2-methyl-4-(4-methoxyphenylazo)phenol

The crystal and molecular structure of 2-methyl-4-(4-methoxyphenylazo)phenol have been determined by X-ray single crystal diffraction technique. The compound crystallizes in the monoclinic space group P2₁/c with a=9.7763(8) Å, b=11.3966(8) Å, c=11.9531(8) Å and β=108.752(6)°. In addition to the molecular geometry from X-ray experiment, its optimized molecular structure has been obtained with the aid of PM3 semiempirical quantum mechanical method, and then the corresponding geometric parameters were compared with those of X-ray crystallography. To determine conformational flexibility and crystal packing effects on the molecules, molecular energy profile of the title compound was obtained with respect to two selected degrees of torsional freedom, which were varied from ?180° to +180° in steps of 10°. Crystal structure of the title compound is a fibroid structure constructed by C–H···O and O–H···N type intermolecular hydrogen bonds. The most favorable conformer of the title compound has been determined by the crystal packing effects and there is no steric hindrance during rotation around the selected torsion angles.     

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.     

Über Chalkogenolate. 191. Ester der 2-Oxophenyldithioessigsäure 2. Kristall- und Molekülstruktur des Methylesters

On Chalcogenolates. 191. Esters of 2-Oxophenyldithioacetic Acid. 2. Crystal and Molecular Structure of the Methyl Ester The title compound C₆H₅? CO? CS? SCH₃ crystallizes with Z = 2 in the triclinic space group P1 with cell dimensions (?60°C) a = 6.236(4) Å, b = 7.972(2) Å, c = 9.589(4) Å, α = 88.42(3)°, β = 75.39(5)°, γ = 81.54(4)°. The structure has been determined from single crystal X-ray data measured at ?60°C and refined to R = 0.085 and R_w = 0.087 for 2307 independent reflections. With nearly 20° the C?O bond is turned out of the plane of the phenyl ring.     

The reactivities of Mo cluster — A selective substitution reaction of the bridging (dtp) ligand and the crystal structure of {Mo3S4(μ-O2CR)(dtp)3(Py)}

The reaction of trinuclear molybdenum cluster {Mo₃S₄(μ-dtp) (dtp)₃ (H₂O)} 1 [dtp= S₂P(OEt)₂] with RCO₂Na (R?H, CH₃) in the presence of Py gave the black compounds {Mo₃S₄ {μ-O₂ CR) (dtp)₃ (Py)} (2, R?H, 3, R?CH₃). Both compounds are characterized by X-ray crystallography. It is shown that crystals 2 and 3 belong to space group P&1bar; with Z=2 and a=10.519(2), b= 12.121(2), c=15.757(2)Å, α=93.27(1), β=94.63(1), γ = 105.22(1)°, V= 1925 ų for crystal 2, whereas a=9.556 (2), b=14.067(7), c=15.914 (9) Å, α=101.41 (4), β=101.44(4), γ-74.26(3)°, V=1994ų for crystal 3. The final R factors are 0.041 and 0.048 for crystal 2 and 3 respectively. The structure analysis indicates that (O₂CR)^? ligand selectively substitutes the bridging (dtp) ligand. This type of Mo, cluster molecule where structure contains two species of bidentate ligand is for the first time to be obtained by us.     

Structure, DNA Binding Studies of Complex {[Cu(phen)(py)(H_2O)_2]·2H_2O}_n

A copper(II) complex of type {[Cu(phen)(py)(H₂O)₂]·2H₂O}_n (where phen=1,10‐phenanthroline, py=pyridine‐3,4‐dicarboxylate) has been synthesized by a normal temperature volatilization method and structurally determined by single‐crystal X‐ray crystallography. The crystal belongs to monoclinic system, space group P2(1)/c with the crystal cell parameters of a=7.5258(4) Å, b=12.3184(7) Å, c=21.0000(12) Å, α=90.00°, β=98.0720(10) °, γ=90.00°, V=1927.53(19) ų and Z=4. The final reliability factors are R=0.0398 and wR=0.1138 for 3771 reflections with I>2δ(I₀). Its mode of interaction with DNA and the binding constants have been determined by fluorescence, ultraviolet spectra and viscometry.     

A new mesogenic fluorene derivative: 2,7-bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene

The title compound, 2,7-bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene, is a new mesogenic compound containing the fluorene moiety. It exhibits a monotropic nematic liquid crystalline behaviour, with isotropisation temperature of 53°C. The compound is also polymorphic in the solid state, with one crystal phase melting at 103°C and another one melting at 71°C. The crystal and molecular structure of the high melting solid phase have been determined from single crystal X-ray diffraction analysis. Crystals are monoclinic, with cell dimensions a = 16.649(6) Å, b = 8.305(3) Å, c = 24.598(7) Å, β = 111.60(2)?, space group P2₁/c and four molecules in the unit cell. Refinement leads to R = 0.0558. The two terminal alkyl chains and one phenyl ring are disordered over two split positions. The imbricated molecular packing observed in the solid state seems to resemble that of the nematic phase that is formed upon cooling the melt.     

Weak Interactions Involving Fluorine in Suppramolecular Assemblies of Cu(Ⅱ)Complexes

Syntheses and X‐ray structural characterizations of two new Cu(II) complexes Cu(tfbz)₂(Htfbz)₂(phen) ( 1 ) (Htfbz=2,4,5‐trifluorobenzoic acid, phen=1,10‐phenanthroline) and [Cu(pfbz)₂(phen)]₂(Hpfbz)₂ ( 2 ) (Hpfbz=pentafluorobenzoic acid) are reported. The first complex crystallizes in the monoclinic space group C2/c with the crystal cell parameters a=1.9903(4) nm, b=1.3688(3) nm, c=1.3623(3) nm, β=97.90(3)°, V=3.6762(13) nm³ and Z=4. The second complex crystallizes in the triclinic space group P‐1 with the crystal cell parameters a=1.7965(4) Å, b=1.9236(2) Å, c=2.0916(2) Å, α=110.156(2) °, β=105.040(3) °, γ=98.123(3) °, V=6.3372(17) nm³ and Z=4. The crystallographic analyses revealed that F···H–C hydrogen bonds in both complexes lead to formation of infinite three‐dimensional supramolecular networks. A large number of F···F interactions in complex 2 ensure the stability of intricate crystal structure.     

Über Chalkogenolate. 111. Untersuchungen über Perthiocyansäure. 4. Kristall- und Molekülstruktur von Dimethylperthiocyanat

On Chalcogenolates. 111. Studies on Perthiocyanic Acid. 4. Crystal and Molecular Structure of Dimethyl Perthiocyanate (CH₃)₂C₂N₂S₃ crystallizes with Z = 4 in the monoclinic space group P2₁/c with cell dimensions a = 7.661(4) Å, b = 11.675(5) Å, c = 9.549(5) Å, β = 116.7(3)·. The crystal and molecular structure has been determined from single X-ray data at 20°C and refined to a conventional R of 0.062. The structure consists of isolated 3,5-bis(methylmercapto)-1,2,4-thiadiazole molecules. The 1,2,4-thiadiazole ring is plane and stabilized by mesomerism.     

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.     

Synthesis,Structure and Thermodynamic Property of a New Lithium Borate: Li4[B8O13(OH)2]·3H2O

A new hydrated lithium borate, Li₄[B₈O₁₃(OH)₂]·3H₂O, has been hydrothermally synthesized and characterized by single crystal X‐ray diffraction, FT‐IR spectroscopy, simultaneous TGA‐DTA and chemical analysis. It crystallizes in the triclinic, space group , a=8.4578(5) Å, b=8.7877(5) Å, c=10.8058(7) Å, α=87.740(3)°, β=71.819(3)°, γ=61.569(3)°, Z=2, V=665.26(7) ų, D_c=2.043 g/cm³. Its crystal structure features polyborate anionic layers with the larger odd 13‐membered boron rings constructed by [B₈O₁₃(OH)₂]^4? FBBs. Through designing the thermochemical cycle, the standard molar enthalpy of formation of this borate was determined to be ?(7953.8±6.6) kJ·mol^?1 by using a heat conduction microcalorimeter.