2,2′‐Bi[benzo[b]thiophene]: an unexpected isolation of the benzo[b]thiophene dimer

The crystal structure of 2,2′‐bi[benzo[b]thiophene], C₁₆H₁₀S₂, at 173 K has triclinic (P) symmetry. It is of interest with respect to its apparent mode of synthesis, as it is a by‐product of a Stille cross‐coupling reaction in which it was not explictly detected by spectroscopic methods. It was upon crystal structure analysis of a specimen isolated from the mother liquor that this reaction was determined to give rise to the title compound, which is a dimer arising from the starting material. Two independent half‐molecules of this dimer comprise the asymmetric unit, and the full molecules are generated via inversion centers. Both molecules in the unit cell exhibit ring disorder, and they are essentially identical because of their rigidity and planarity.     

Angular‐Resolved Magnetometry Beyond Triclinic Crystals: Out‐of‐Equilibrium Studies of Cp*ErCOT Single‐Molecule Magnet

Angular‐resolved single‐crystal magnetometry is a key tool to characterise lanthanide‐based materials with low symmetry, for which conjectures based on idealised geometries can be totally misleading. Unfortunately the technique is strictly successful only for triclinic structures, thus reducing significantly its application. By collecting out‐of‐equilibrium magnetisation data the technique was extended to the orthorhombic organometallic Cp*ErCOT single‐molecule magnet (SMM), thus allowing for the first time the reconstruction of the molecular anisotropy tensor notwithstanding the two molecular orientations in the crystal lattice. The results, flanked by state‐of‐the‐art ab initio calculations, confirmed the expected orientation of the molecular easy axis of magnetisation and thus validated the synthetic strategy based on organometallic complexes of a single lanthanide ion.     

Crystal structure of 5,6‐bis(9H‐carbazol‐9‐yl)benzo[c][1,2,5]thiadiazole: distortion from a hypothetical higher‐symmetry structure

Nucleophilic substitution of F atoms in 5,6‐difluorobenzo[c ][1,2,5]thiadiazole (DFBT) for carbazole could be potentially interesting as a novel way of synthesizing building blocks for new conjugated materials for applications in organic chemistry. The crystal structures of 5,6‐bis(9H‐carbazol‐9‐yl)benzo[c ][1,2,5]thiadiazole (DCBT), C₃₀H₁₈N₄S, and its hydrate, C₃₀H₁₈N₄S·0.125H₂O, were investigated using single‐crystal X‐ray analysis. The hydrate contains two symmetry‐independent DCBT molecules. The dihedral angles between the plane of the central benzothiadiazole fragment and that of the carbazole units vary between 50.8 and 69.9°, indicating conformational flexibility of the DCBT molecule in the crystals, which is consistent with quantum chemical calculations. The analysis of the crystal packing of DCBT revealed that the experimental triclinic structure could be described as a distortion from a hypothetical higher‐symmetry monoclinic structure. The quantum chemical calculations of two possible monoclinic structures, which are related to the experimental structure by a shifting of molecular layers, showed that the proposed structures are higher in energy by 5.4 and 10.1 kcal mol⁻¹. This energy increase is caused by less dense crystal packings of the symmetric structures, which results in a decrease of the number of intermolecular interactions.     

Mometasone furoate revisited,or how did the hydrate get in the bottle?

The redetermined structure of 9α,21‐dichloro‐11β,17α‐dihydroxy‐16α‐methyl‐3,20‐dioxopregna‐1,4‐dien‐17‐yl furan‐2‐carboxylate monohydrate, C₂₇H₃₂Cl₂O₇·H₂O, at 100 K has triclinic (P1) symmetry. The structure displays O—H...O hydrogen bonding, which gives rise to infinite sheets extending parallel to the [110] plane. The previously published structure [Chen et al. (2005). J. Pharm. Sci. 94 , 2496–2509] was determined at room temperature and no significant anomalous signal was present. Data for the structure presented in this study were collected at low temperature and the absolute configuration could be established based solely on anomalous diffraction. Another point of interest is that the structure determined in this study is that of the monohydrate, even though the crystal was harvested from a bottle of nasal spray that was supposed to contain exclusively crystals of the anhydrous form.     

A sodium salt of the dimer of boronoterephthalic acid anhydride

The title compound, sodium bis(6‐carboxy‐1‐hydroxy‐3‐oxo‐1,3‐dihydro‐2,1‐benzoxaborol‐1‐yl)oxidanium, Na⁺·C₁₆H₁₅B₂O₁₃⁻, was prepared in two steps from 2‐bromo‐p‐xylene. Its crystal structure was determined at 140 K and has triclinic (P) symmetry. The compound presents a unique structural motif, including two units of the cyclic anhydride of boronoterephthalic acid, joined by a protonated, and thereby trivalent, oxonium center. Association in the crystal is realized by complementary hydrogen bonding of the carboxyl groups, as well as by coordination of the sodium cations to the oxygen centers on the five‐membered rings.     

A New Copper(II) Complex with the N,N′‐Tetra(antipyryl‐4‐methyl)‐1,2‐ethanediamine (TAMEN) Ligand: [Cu(TAMEN)](ClO4)2·H2O·DMF

The synthesis of the Mannich base N,N′‐tetra(antipyryl‐4‐methyl)‐1,2‐ethanediamine (TAMEN) ( 1 ), its crystal structure as well as the synthesis and the crystal structure of the copper complex [Cu(TAMEN)](ClO₄)₂·H₂O·DMF ( 2 ) are reported. C₅₀H₅₆N₁₀O₄·2C₂H₅OH (TAMEN·2EtOH) crystallizes with triclinic symmetry, space group , lattice parameters: a = 877.3(1), b = 1078.1(1), c = 1433.3(2) pm, α = 71.93(1), β = 82.16(1), γ = 84.54(1)° and Z = 1. The copper complex [Cu(TAMEN)](ClO₄)₂·H₂O·DMF also crystallizes with triclinic symmetry, space group , lattice parameters: a = 1279.2(2), b = 1485.6(2), c = 1513.6(2) pm, α = 98.04(1), β = 101.24(1), γ = 94.66(1)° and Z = 2. The copper(II) atom is six‐coordinate with an elongated pseudo‐octahedral geometry due to a strong Jahn‐Teller effect.     

Pseudosymmetry in the crystal structure of 2,6-dimethyl-3,5-dicarbomethoxy-4-(2′,3′-dichlorophenyl)-1,4-dihydropyridine

Within the framework of a detailed crystallochemical analysis a comparison of the structures of symmetrically independent molecules was performed and the energy of intermolecular interaction was calculated for a triclinic bisystem crystal, 2,6-dimethyl-3,5-dicarbomethoxy-4-(2′,3′-dichlorophenyl)-1,4-dihydropyridine. Pseudosymmetrical operations were detected and identified. The presence of highly efficient layers with pseudomonoclinic symmetry was disclosed in this structure.     

Pseudo‐merohedrally twinned tetra­kis­(1H‐imidazole‐κN3)bis­(N‐nitro­cyanamidato‐κN)copper(II)

Crystals of the title complex, [Cu(CN₃O₂)₂(C₃H₄N₂)₄], the structure of which has been determined by single‐crystal X‐ray diffraction at 304 K, appear to be pseudo‐merohedrally twinned. Transformation to a monoclinic C‐centred cell was necessary in order to derive the twin law. Twin refinement in a triclinic unit cell significantly reduced the R value. The asymmetric unit of the triclinic cell consists of one mol­ecule in a general position and two half entities with the Cu atom on a centre of inversion. The coordination of the Cu atom is quasi‐octa­hedral, with four imidazole N‐atom donors in the equatorial plane and two cyano N atoms from the N‐nitro­cyanamidate anion in axial positions. Owing to symmetry in the centrosymmetric mol­ecules, the trans imidazole ligands are parallel, while those in the non‐centrosymmetric mol­ecule make angles of 22.8 (2) and 77.9 (2)°.     

Kristall- und Molekülstruktur von Bis(N,N-diethyl-2-benzoylthioacetamidato)kupfer(II)

Crystal and Molecular Structure of Bis(N, N-diethyl-2-benzoylthioacetamidato)copper(II) Bis(N, N-diethyl-2-benzoyl-thioacetamidato)copper(II) has been investigated by X-ray structure analysis. It crystallizes in the triclinic space group P1 with a = 10.709, b = 12.150, c = 15.651 Å, α = 90.13, β = 103.73, γ = 98.30° and with 3 formula units per unit cell. The structure was solved by heavy atom technique. The final R value was 0.04 for 4151 symmetry independent reflections. The crystal contains two symmetry independent molecules. One of them shows a nearly planar cis-arrangement of the ligator atoms but the other has an exactly planar trans-arrangement. The chelate rings show a distorted planarity in both molecules. The results of the structure determination confirm the conclusions from the EPR crystal spectrum.     

Zur Struktur von N-Benzoylthiobenzamid

Structure of N-Benzoylthiobenzamide N-Benzoylthiobenzamide forms two polymorphic modifications of which the crystal and molecular structures have been determined by X-ray structure analysis. In both modifications the molecules exist as NH tautomeres, but there are differences with regard to their rotameric configurations. In the monoclinic modification both symmetry independent molecules have a Z,Z′ configuration. The triclinic modification also contains two symmetry independent molecules, but now a Z,Z′ and an E,Z′ configuration exist. All four molecules deviate appreciably from planarity. The results of both structure determinations are compared with each other and with the structure of monothiodibenzoylmethane.     

Spectral characterization and crystal structure of 2-benzoylpyridine nicotinoyl hydrazone

The synthesis, spectral characterization and crystal structure of 2-benzoylpyridine nicotinoyl hydrazone (HL) is reported. Spectral techniques employed include 1H NMR, COSY homonuclear, HSQC heteronuclear correlation techniques, electronic and IR. The infrared spectrum suggests the existence of the compound in keto form in solid state, which is further established by the single crystal X-ray analysis. The compound crystallizes into a triclinic lattice with P-1 symmetry with two molecules per unit cell.     

X‐Ray Diffraction and Mössbauer Spectroscopy Studies of Pressure‐Induced Phase Transitions in a Mixed‐Valence Trinuclear Iron Complex

The mixed‐valence complex Fe₃O(cyanoacetate)₆(H₂O)₃ ( 1 ) has been studied by single‐crystal X‐ray diffraction analysis at pressures up to 5.3(1) GPa and by (synchrotron) Mössbauer spectroscopy at pressures up to 8(1) GPa. Crystal structure refinements were possible up to 4.0(1) GPa. In this pressure range, 1 undergoes two pressure‐induced phase transitions. The first phase transition at around 3 GPa is isosymmetric and involves a 60° rotation of 50 % of the cyanoacetate ligands. The second phase transition at around 4 GPa reduces the symmetry from rhombohedral to triclinic. Mössbauer spectra show that the complex becomes partially valence‐trapped after the second phase transition. This sluggish pressure‐induced valence‐trapping is in contrast to the very abrupt valence‐trapping observed when compound 1 is cooled from 130 to 120 K at ambient pressure.     

Concomitant polymorphic forms of 3‐cyclopropyl‐5‐(2‐hydrazinylpyridin‐3‐yl)‐1,2,4‐oxadiazole

The dipharmacophore compound 3‐cyclopropyl‐5‐(2‐hydrazinylpyridin‐3‐yl)‐1,2,4‐oxadiazole, C₁₀H₁₁N₅O, was studied on the assumption of its potential biological activity. Two concomitant polymorphs were obtained on crystallization from isopropanol solution and these were thoroughly studied. Identical conformations of the molecules are found in both structures despite the low difference in energy between the four possible conformers. The two polymorphs differ crucially with respect to their crystal structures. A centrosymmetric dimer formed due to both stacking interactions of the `head‐to‐tail' type and N—H…N(π) hydrogen bonds is the building unit in the triclinic structure. The dimeric building units form an isotropic packing. In the orthorhombic polymorphic structure, the molecules form stacking interactions of the `head‐to‐head' type, which results in their organization in a column as the primary basic structural motif. The formation of N—H…N(lone pair) hydrogen bonds between two neighbouring columns allows the formation of a double column as the main structural motif. The correct packing motifs in the two polymorphs could not be identified without calculations of the pairwise interaction energies. The triclinic structure has a higher density and a lower (by 0.60 kcal mol^?1) lattice energy according to periodic calculations compared to the orthorhombic structure. This allows us to presume that the triclinic form of 3‐cyclopropyl‐5‐(2‐hydrazinylpyridin‐3‐yl)‐1,2,4‐oxadiazole is the more stable.     

Crystalline Structure of Mangiferin,a C‐Glycosyl‐Substituted 9H‐Xanthen‐9‐one Isolated from the Stem Bark of Mangifera indica

The crystalline structure of mangiferin (=2‐β‐D ‐glucopyranosyl‐1,3,6,7‐tetrahydroxy‐9H‐xanthen‐9‐one; 1 ), a biologically active xanthenone C‐glycoside, isolated from the stem bark of Mangifera indica (Anacardiaceae), was unambiguously determined by single‐crystal X‐ray diffraction (XRD). The crystal structure is summarized as follows: triclinic, P1, a=7.6575(5), b=11.2094(8), c=11.8749(8) Å, α=79.967(5), β=87.988(4), γ=72.164(4)°, V=955.3(1) ų, and Z=2. The structure also shows two molecules in the asymmetric unit cell and five crystallization H₂O molecules. The packing is stabilized by several intermolecular H‐bonds involving either the two symmetry‐independent mangiferin molecules 1a and 1b , or the H₂O ones.     

Redetermination of iron dialuminide,FeAl2

The crystal structure of iron dialuminide [Corby & Black (1973). Acta Cryst. B 29 , 2669–2677] has been redetermined on a single crystal synthesized from the elements by arc melting. The compound crystallizes in the triclinic space group P with 19 atoms per unit cell, one Fe site being on an inversion centre. The crystal structure can be described as an inclusion‐plus‐deformation derivative of the orthorhombic YPd₂Si structure type.     

Concomitant polymorphism in the stereoselective synthesis of a β‐benzyl‐β‐hydroxyaspartate analogue

Two concomitant polymorphs, (I) and (II), of a β‐benzyl‐β‐hydroxyaspartate analogue [systematic name: dibenzyl 2‐benzyl‐2‐hydroxy‐3‐(4‐methylphenylsulfonamido)succinate], C₃₂H₃₁NO₇S, crystallize from a mixture of ethyl acetate and cyclohexane at ambient temperature. The structure of (I) has triclinic (P) symmetry and that of (II) monoclinic (P2₁/c) symmetry. Both crystal structures are made up of a stacking of homochiral racemic dimers (2S,3S and 2R,3R) which are internally connected by a similar R₂²(9) hydrogen‐bonding pattern consisting of intermolecular N—H...O and O—H...O hydrogen bonds. The centroid of the racemic dimer lies on an inversion centre. The main structural difference between the two polymorphs is the conformational orientation of two of the four aromatic rings present in the molecule. Polymorph (II) is found to be twinned by reticular merohedry with twin index 3 and twin fractions 0.854 (1) and 0.146 (1).     

1,3-Di（2-p-tolylvinyl）-2,4,6-trinitrobenzene： X-ray Crystallo- graphic Analysis,Thermal Decomposition and DFT Calculations

In this paper, the synthesis, crystal culturing and single-crystal X-ray crystallography of 1,3-di（2-p-tolylvingl）-2,4,6-trinitrobenzene （DTTB） were reported. FT-IR, ^1H NMR and mass spectroscopy techniques were employed to characterize this compound. The results show that this single crystal belongs to triclinic system with space group P-1. Density functional theory （DFT） B3LYP was employed to optimize structure and calculate frequencies of the title compound. The calculated geometrical parameters were close to the corresponding experiment ones. The thermal decomposition of DTTB was investigated by DSC and TG-DTG methods at the heating rate of 10 ℃/min. It was observed that the initial decomposing temperature of DTTB was higher than that of TNTM, although its melting point was lower than that of TNTM, indicating that DTTB has higher heat resistant ability.     

Initial stage of fiber structure development in the continuous drawing of poly(ethylene terephthalate)

The initial stage of fiber structure development in the continuous neck‐drawing of amorphous poly(ethylene terephthalate) fibers was analyzed by in situ wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, and fiber temperature measurements. The time error of the measurements (<600 μs) was obtained by synchrotron X‐ray source and laser irradiation heating. A highly ordered fibrillar‐shaped two‐dimensional (smectic‐like) structure was found to be formed less than 1 ms after necking. By analyzing its (001′) and (002′) diffractions, the length of the structure 60–70 nm were obtained. A three‐dimensionally ordered triclinic crystal began to form with the vanishing of the structure around 1 ms after necking. The amount and size of the crystal were almost saturated within several milliseconds of necking, during which time a mainly exothermic heat of crystallization was also observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2126–2142, 2008     

Synthesis and Structure of a 2, 8, 9‐Trioxa‐3, 5, 7‐trisila‐1‐titanaadamantane

The title compound has been prepared from [Ti(η⁵‐C₅Me₅)Cl₃] and cis‐cis‐(t‐BuSi(OH)—CH₂)₃ in hexane solution in the presence of Et₃N. The pale yellow complex was characterized by NMR and MS spectra, as well as by a crystal structure determination. The two crystallographic independent molecules in the triclinic unit cell (space group P1¯, No. 2, Z = 4) both have a nearly identical adamantane‐like TiO₃Si₃C₃ cage of approximate C_3v symmetry. The exocyclic C—C—C bond angles in the Cp‐ligand range from 123° to 129°. A quantum chemical calculation of the free molecule predicts this range to be 124° to 127°. The arrangement of the molecules in the crystal is characteristic for an offset face‐to‐face ππ stacking of the aromatic η⁵‐C₅Me₅ rings.