Acta Crystallographica Section E: Crystallographic Communications最新文献

The crystal structure of the title salt, C₉H₁₄NO₂ ⁺·HC₄H₄O₆ ^-, has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. The crystal structure consists of alternating hydro-phobic and hydro-philic layers lying parallel to the ab plane. Hydrogen bonds link the cations and anions in the hydro-philic layers. The anions are linked by very strong charge-assisted O-H⋯O hydrogen bonds into chains propagating along the a-axis direction. Each H atom of the protonated N atom of the cation acts as a donor in at least one N-H⋯O hydrogen bond to an anion.

Zinc bis-[catena-arsenate(V)] or catena-poly[zinc-di-μ-arsenato(V)-κ⁴ O:O], [Zn(AsO₃)₂] _n , is isotypic with the low-temperature modification of Zn(PO₃)₂. The asymmetric unit comprises one Zn atom situated on a twofold rotation axis and one As and three O atoms in general positions. In the crystal structure, the principal building units, ZnO₆ octa-hedra and AsO₄ tetra-hedra, are condensed into ¹ _∞[ZnO_4/2O_2/1] zigzag chains and (AsO₃)₂ polyarsenate chains with a periodicity of two AsO₄ tetra-hedra, respectively. The two types of chains extend parallel to [001] and are fused into a compact framework structure. Compared with divalent transition metal arsenates and other arsenates of the formula M ^IIAs₂O₆, Zn(AsO₃)₂ is unique in that arsenic is present exclusively in a tetra-hedral coordination and not in a mixed tetra-hedral/octa-hedral or purely octa-hedral coordination.

The title compound, C₂₆H₂₂N₆ ²⁺·2Cl^-·6H₂O, crystallizes in the monoclinic space group P2₁/n with one mol-ecule in the asymmetric unit. Structure determination at 150 K from a two-component twin crystal reveals the non-symmetrical n-shaped dication, where two pyridine-imidazole fused cores bearing pendant pyridyl rings are linked by an ethyl-ene bridge. The fused five- and six-membered rings are almost coplanar with the largest deviation from the mean plane being 0.019 Å for a nitro-gen atom of one of the rings. The pendant pyridyl groups are twisted by 42.14 (11) and 46.47 (11)° with respect to the planes of the adjacent imidazo[1,5-a]pyridinium cores. In the crystal, the dications stacked along the b-axis direction are linked by π-π inter-actions that possibly stabilize the n-type structure in the solid state. The chloride anions and water mol-ecules form R ² ₄(8), R ⁵ ₅(12), R ⁶ ₆(12) and R ⁸ ₁₁(22) ring motifs through O-H⋯O/Cl hydrogen bonds, building corrugated layers that run between columns of the stacked organic dications.

The title compound, C₂₄H₁₄F₂N₂O₂, was studied by single-crystal and powder X-ray diffraction methods. The title compound crystallizes in the monoclinic space group P2₁/c with one mol-ecule in the asymmetric unit. The two chemically equivalent substituents adopt different orientations relative to the central benzene ring. The dihedral angles between the central benzene and oxazole rings are 2.4 (2) and 57.6 (2)°, while those between the oxazole and terminal 4-fluoro-phenyl rings are 13.3 (2) and 2.5 (2)°, respectively. In the crystal, inversion-related mol-ecules form dimers through π-π stacking between oxazole rings [centroid-to-centroid distance = 3.587 (3) Å] and C-H⋯N hydrogen bonds. The dimers are further connected by C-H⋯N inter-actions into layers parallel to (100). Hirshfeld surface analysis indicates that C⋯H/H⋯C (30.2%), H⋯H (21.8%) and F⋯H/H⋯F (18.0%) contacts make the largest contributions to the crystal packing.

Although solving and refining a crystal structure using synchrotron powder diffraction data can be routine, many problems present features which make the process more difficult. These include difficulty in indexing, incorrect or approximate symmetry, and chemically unreasonable models (poor conformations, incorrect compounds). Examples of each of these 'inter-esting' features are provided, as well as the methods used for recognizing and overcoming them. Raw data and GSAS-II project files are provided for all of the examples.

Potassium 2-eth-oxy-2-oxo-acetate, K⁺·C₄H₅O₄ ^-, was identified as a byproduct in the first step of synthesizing the shelf-stable salt potassium nitro-aceto-nitrile (KNAN). A single crystal of the title salt was obtained by recrystallization of the ethanol filtrate resulting from the purification of the intended product salt, potassium ethyl nitro-cyano-acetate. The asymmetric unit of K⁺·C₄H₅O₄ ^-, contains a single potassium cation and a 2-eth-oxy-2-oxo-acetate anion, the ethyl group of which is disordered over two sets of sites in a 0.792 (13):0.208 (13) ratio. The packing is dictated primarily by K-O electrostatic inter-actions and comprises eight bonded oxygen atoms per cation, with distances ranging from 2.706 (2) to 3.053 (4) Å.

The title compound, C₁₂H₈ClNO, is a pharmaceutical impurity and possible inter-mediate in the synthesis of carbinoxamine. The aromatic rings of the mol-ecule twist relative to one another resulting in an inter-planar angle of 38.1 (1)°. In the extended structure, the mol-ecules are packed into rippled sheets with offset face-to-face stacking of each aromatic ring with the equivalent ring in the neighboring mol-ecule.

The stable conformation of the title mol-ecule, C₂₉H₂₄N₆O₅S, is caused by two intra-molecular N-H⋯N hydrogen bonds producing fused S(5) and S(6) rings. In the crystal, mol-ecules are connected by inter-molecular N-H⋯O inter-actions along the b-axis direction, forming C(9) chains. Furthermore, there are π-π inter-actions [centroid-to-centroid distance = 3.8200 (12) Å] between the benzene ring of the p-tolyl group and the 1,2,4-triazine ring in the same direction. As a result, the mol-ecules form ribbons along the b-axis direction,. A Hirshfeld surface analysis was performed, showing the predominance of H⋯H, O⋯H/H⋯O, C⋯H/H⋯C and N⋯H/H⋯N contacts.

The solid-state structures of 4-hy-droxy-N,N-di-ethyl-tryptammonium (4-HO-DET) hydro-fumarate {systematic name: dieth-yl[2-(4-hy-droxy-1H-indol-3-yl)eth-yl]aza-nium 3-carb-oxy-prop-2-enoate}, C₁₄H₂₁N₂O⁺·C₄H₃O₄ ^-, and 4-acet-oxy-N,N-di-ethyl-tryptammonium (4-AcO-DET) fumarate/fumaric acid {systematic name: bis-{[2-(4-acet-oxy-1H-indol-3-yl)eth-yl]di-ethyl-aza-nium} but-2-ene-dio-ate-(E)-butenedioic acid (1/1)}, 2C₁₆H₂₃N₂O²⁺·C₄H₂O₄ ^2-·C₄H₄O₄, were determined by single-crystal X-ray diffraction. The 4-HO-DET structure exhibits a single tryptammonium cation and a single hydro-fumarate anion in the asymmetric unit. The ions are joined together by N-H⋯O and O-H⋯O hydrogen bonds in two-dimensional sheets lying in the (001) plane. The 4-AcO-DET structure exhibits a single tryptammonium cation, half of a fumarate dianion and half of a fumaric acid mol-ecule in the asymmetric unit. The ions and mol-ecules are joined together by N-H⋯O and O-H⋯O hydrogen bonds in an infinite three-dimensional network.

The title mol-ecule, C₉H₁₀N₂, exhibits whole-mol-ecule disorder in a 0.849 (4)/0.151 (4) ratio. The bicyclic portion is planar. In the crystal, a layer structure parallel to the ac plane is generated by N-H⋯N hydrogen bonds and C-H⋯π(ring) inter-actions. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H, C⋯H/H⋯C and N⋯H/H⋯N inter-actions.