search results

X-ray diffraction study of the title compound, C₁₁H₁₁NO₂, (I), has shown that the molecular geometry is similar to that of 1-ethyl-4-hydroxy-2-oxo-1,2-di­hydro­quinoline-3-carboxyl­ic acid, (II) [Shishkina, Shishkin, Ukrainets, Dakkah & Sidorenko (2002). Acta Cryst. E58, o254-o256]. Observed elongations of the bonds around the N atom are caused by steric hindrance between the ethyl H atoms and the planar quinolone fragment. Exocyclic angles in the 4-position are also distorted, but, in contrast to (II), this distortion is caused by the formation of zigzag hydrogen-bonded chains along the [010] direction.

The asymmetric unit of the title compound, C₂₅H₂₂N₃O₂⁺·Cl^-·C₂H₄O₂, is composed of a 5-benzyl-7,9-di­methoxy-3-phenyl-5H-pyrazolo­[4,3-c]­quinolin-1-ium cation, a chloride anion and an acetic acid solvent mol­ecule. The positive charge of the cation is located on the pyrazole ring, resulting in aromatization of the bonds in the pyrazolo­[4,3-c]­quinoline tricyclic system. The pyrazolium H atom forms a bifurcated hydrogen bond with the O atom of the 6-methoxy group [NO = 2.741 (2) Å and N-HO = 117°] and with the carbonyl O atom of the acetic acid mol­ecule [NO = 2.826 (2) Å and N-HO = 134°]. Another hydrogen bond is observed between the acetic acid hydroxy group and the chloride anion [ClO = 2.972 (2) Å and O-HCl = 172°].

On heating N'-benzoyl-7-hydroxy-6-hexyl-2-oxo-2H-chromene-3-carbohydrazon­amide in di­methyl­form­amide, the process of cyclization leads to the formation of a triazole derivative of a 3-substituted chromenone, C₂₃H₂₃N₃O₃·H₂O, as confirmed by this crystal structure investigation. The three ring systems are almost coplanar and, in the crystal structure, a three-dimensional network of hydrogen bonds is formed; these are of the types O-HO, N-HN, O-HN and C-HO.

Details of the crystal structure and quantum chemistry calculations of the title mol­ecule, C₁₃H₉BrO, illustrate the effects of intermolecular interactions and the substitution of one of the two aromatic rings on the molecular conformation. The asymmetry of the mol­ecule is documented by the two C_aryl-C_aryl-C=O torsion angles of -68.3 (5) and -17.6 (6)°. A C-HO hydrogen bond [HO = 2.5 Å, CO = 3.412 (5) Å and C-HO = 174°] and a C-H contact involving the H atom at position 4 of the substituted ring and the -system of the unsubstituted ring of an adjacent mol­ecule [HCg = 2.96 Å, CCg = 3.806 (5) Å and C-HCg = 153°; where Cg is the centroid of the unsubstituted ring] are observed in the crystal structure.

Mol­ecules of the title mol­ecule, C₂₁H₂₃NO₅S, form centrosymmetric dimers via inter­molecular N-HO bonds. In addition, there are inter­molecular C-HO bonds. The eight-membered ring and both six-membered rings belonging to the tricycic ring system adopt a conformation which is intermediate between a sofa and a half-chair.

The title mol­ecule, C₁₆H₁₉ClN₂O₂, contains three planar fragments, i.e. the quinoline system (A), the butyl­amino group (B) and the carboxyl group (C). Angles A/B and A/C are 9.1 (2) and 79.08 (4)°, respectively. The alternation of the bond lengths in the quinoline bicycle correlates with literature data.

In the title compound, C₁₈H₁₆N₃O₂⁺·ClO₄^-, the almost planar cation contains bicyclic chromenone and benz­imidazole moieties, which are rotated slightly relative to each other. The positive charge of the cation is located on the pyrilium ring and causes noticeable aromatization of the O-C and C-C bonds. One of the H atoms of the amino group is involved in an intramolecular hydrogen bond which closes the six-membered pseudo-ring in the cation. The second H atom of the amino group participates in a hydrogen bond with one of the O atoms of the perchlorate anion.

In the title mol­ecule, C₂₅H₂₂N₂O₃S₂, the two C-S bond lengths of the thio­phene ring are significantly different, at 1.719 (2) and 1.758 (2) Å. In the crystal structure, mol­ecules form centrosymmetric dimers via inter­molecular N-HO hydrogen bonds.

Comparison of the title compound, C₂₀H₂₈N₂O₅S, with related structures shows that the presence of the alkyl substituents influences the conformation of the rings in the frame fragment. The mol­ecules form hydrogen-bonded centrosymmetric dimers due to an N-HS inter­molecular inter­action.

The coplanar arrangement of rings in the title mol­ecule, C₂₅H₁₈Cl₃N₃O₄, is accompanied by the formation of short intramolecular OH (2.20 and 2.26 Å) contacts. A strong N-HN hydrogen bond [NN = 2.698 (4) Å and N-HN = 142°] is present and, as a result, the exocyclic bond angles at the C atoms in the 2- and 3-positions of the pyran­one ring are slightly distorted. The coplanar rings form a layered structure in which a short intermolecular ClCl(-x, 1 - y, 1 - z) contact of 3.280 (2) Å is observed.

In the title compound, C₁₄H₁₄BrNO₂S, there are two similar non-equivalent mol­ecules in the asymmetric unit, displaying three chiral centres each. In the crystal structure, they are linked by inter­molecular N-HO hydrogen bonds to form infinite chains, which are in turn connected by weak BrH and SH inter­actions.

Crystallization (from ethyl acetate solution) of 2-(4-chloro­phenyl)-4-methyl­chromenium perchlorate, C₁₆H₁₂ClO⁺·;ClO₄^-, (I), yields two monoclinic polymorphs with the space groups P2₁/n [polymorph (Ia)] and P2₁/c [polymorph (Ib)]; in both cases, Z = 4. Cations and anions, disordered in polymorph (Ib), form ion pairs in both polymorphs as a result of Cl-O inter­actions. Related by a centre of symmetry, neighbouring ion pairs in polymorph (Ia) are linked via - inter­actions between cationic fragments, and the resulting dimers are linked through a network of C-HO(perchlorate) inter­actions between adjacent cations and anions. The ion pairs in polymorph (Ib), arranged in pairs of columns along the a axis, are linked through a network of C-HO(perchlorate), C-Cl, - and C-ClO(perchlorate) inter­actions. The aromatic skeletons in polymorph (Ia) are parallel in the cationic fragments involved in dimers, but nonparallel in adjacent ion pairs not constituting dimers. In polymorph (Ib), these skeletons are parallel in pairs of columns, but non­parallel in adjacent pairs of columns; this is visible as a herring-bone pattern. Differences in the crystal structures of the polymorphs are most probably the cause of their different colours.