The crystal structure of the title compound, C₁₆H₂₆NO₂⁺·C₁₈H₁₃O₈⁻, is stabilized by an extensive network of classical N—HO and O—HO hydrogen bonding. The crystal structure also shows an ammonium-driven diastereo­isomerism.

The title compound, [Co(C₈H₄NO₂)₂(H₂O)₂]_n, which was obtained by the reaction of CoCl₂·6H₂O with 4-cyano­benzoic acid, is the first two-dimensional 4-cyano­benzoate cobalt(II) polymer. The Co atom lies on a centre of symmetry and its coordination polyhedron is a slightly distorted octahedron, defined by two water and four carboxyl­ate O atoms. The 4-cyano­benzoate (cba) anion is bridging in a syn-skew coordination mode, which ensures a two-dimensional architecture with the building block Co₄(cba)₄.

In the title mol­ecule, C₁₈H₁₈OS₂, the geometric parameters are normal and the two S atoms are both in an anti arrangement with respect to the carbonyl O atom. The dihedral angle between the thio­phene rings is 5.16 (9)°.

The title compound, C₁₅H₁₄F₂N₂O₃, was obtained in a one-pot three-component reaction from 4-(difluoro­meth­oxy)benzaldehyde, cyclo­hexane-1,3-dione and urea, with a catalytic amount of p-toluene­sulfonic acid. The 4-(difluoro­meth­oxy)phenyl ring is positioned axially, perpendicular to, and bis­ecting the six-membered heterocyclic ring. The heterocyclic ring adopts a puckered boat conformation, whereas the cyclo­hexene ring is in a half-chair conformation. The mol­ecules are linked by N—HO, C—HO, N—HF and C—HF inter­molecular hydrogen bonds.

In the title complex, [CuCl₂(C₁₁H₂₁N₃O)], the five-coordinate Cu atom has a distorted square-pyramidal configuration. The crystal packing is stabilized by inter­molecular N—HCl hydrogen-bonding inter­actions. The furan ring is disordered over two position, with site occupancy factors of ca. 0.6 and 0.4.

The crystal structure of the title compound, [Na(C₂H₃N₄S)(H₂O)₃]_n, features polymeric chains made up of sodium coordination octa­hedra NaS(H₂O)₅, each of them sharing two μ-H₂Oμ-H₂O edges with two adjacent octa­hedra; the chains run along the a axis of the crystal structure. All three unsubstituted N atoms of the tetra­zole ring are involved in the complex hydrogen-bonding system; however, none of them participate in the coordination of the sodium ion.

In the title compound, [Co(C₇H₄FO₂)₂(C₁₂H₈N₂)(H₂O)], the Co^II ion is coordinated by two O atoms from one 3-fluoro­benzoate (fb) ligand and one O atom from another fb ligand, two N atoms from the 1,10-phenanthroline ligand and a water mol­ecule in a distorted octa­hedral geometry. An intra­molecular O—HO hydrogen bond occurs. Inter­molecular O—HO hydrogen bonds link pairs of mol­ecules into centrosymmetric dimers. Weak inter­molecular C—HO and C—HF hydrogen bonds and π–π inter­actions between the aromatic rings [shortest centroid–centroid distance = 3.4962 (2) Å] further stabilize the crystal packing.

In the polymeric title complex, {[Mn(C₈H₄O₄)(C₇H₆N₂)(H₂O)₂]·2H₂O}_n, the Mn^II cation is coordinated by two benzene­dicarboxyl­ate anions, one benzimidazole ligand and two water mol­ecules in a distorted MnNO₅ octa­hedral geometry. In the crystal, each benzene­dicarboxyl­ate anion bridges adjacent Mn^II cations through the terminal carboxyl­ate groups, forming a polymeric complex chain along the a axis. One Mn—O_{carboxyl­ate} bond is much longer than the others. In the crystal, π–π stacking is observed between nearly parallel [dihedral angle = 4.32 (6)°] benzimidazole aromatic ring systems of adjacent mol­ecules, the centroid–centroid distance between the imidazole and benzene rings being 3.5421 (11) Å. Extensive inter­molecular O—HO and N—HO hydrogen bonding is present in the crystal structure. The two lattice water mol­ecules are located on twofold rotation axes.

In the title compound, C₁₆H₂₆NO₂⁺·C₄H₅O₆⁻·2H₂O, a meptaz­inol derivative, three C atoms of the azepane ring are disordered over two positions, with site-occupancy factors of 0.80 and 0.20; the major disorder component adopts a twist-chair conformation, while the minor component has a chair conformation. The benzene ring is axially substituted on the heterocyclic ring, resulting in a folded conformation of the cation. The absolute configuration was determined with reference to D-tartaric acid. The crystal structure is stabilized by an extensive network of intra- and inter­molecular O—HO hydrogen bonds.

The title compound, C₁₄H₁₁BrN₂OS, was synthesized by the reaction of 1,2-benzothia­zol-3(2H)-one with formalin and 3-bromo­aniline in ethanol. The 1,2-benzothia­zolone ring system is approximately planar [maximum deviation = 0.0142 (s.u.?) Å] and forms a dihedral angle of 79.19 (5)° with the benzene ring. In the crystal, molecules are linked by N—HO, C—HO and C—HBr interactions.

In the mol­ecule of the title compound, C₁₉H₂₃N₃O₃, the six-membered rings are oriented at a dihedral angle of 73.06 (3)°. The cyclo­pentyl ring adopts an envelope conformation. In the crystal structure, inter­molecular N—HO and O—HN hydrogen bonds link the mol­ecules. In the tolyl ring, the H atoms and all but one of the C atoms are disordered over two positions and were refined with occupancies of 0.51 (3) and 0.49 (3).

In the mol­ecule of the title compound, C₂₀H₂₅N₃O₃, the aromatic rings are oriented at a dihedral angle of 88.36 (3)°. The cyclo­hexane ring adopts a chair conformation. In the crystal structure, inter­molecular N—HO and O—HN hydrogen bonds link the mol­ecules. C—Hπ inter­actions are also present.

In the title complex, [Cu(ClO₄)₂(C₁₂H₁₆N₂O₂)₂], the six-coordinate Cu atom lies on an inversion center with four amine N atoms in the equatorial plane, with Cu—N distances of 2.049 (3) and 2.055 (3) Å, and two perchlorate O atoms in axial positions, with Cu—O distances of 2.580 (2) Å.

The mol­ecule of the title compound, C₁₂H₁₂O₂, is essentially planar, with a maximum deviation from the mean plane of all non-H atoms of 0.038 (1) Å for the methyl C atom in the 8-position. The crystal structure is characterized by anti­parallel π–π stacking along the c axis, with centroid–centroid distances as short as 3.866 (1) Å. In the crystal, C—HO hydrogen bonds connect the mol­ecules across the stacks into ribbons in the a-axis direction.

The title compound, C₁₂H₁₃NO₃S, was synthesised by the reaction of benzo[d]isothia­zol-3(2H)-one with butyl alcohol in toluene. The benzoisothia­zolone ring system is almost planar with a mean deviation of 0.041 (1) Å. In the crystal, mol­ecules are linked by weak inter­molecular C—HO hydrogen bonds.

In the title compound, C₁₇H₁₄O₅S, the coumarin ring system is nearly planar, with a maximum deviation of 0.034 (2) Å from the mean plane. The dihedral angle between the benzene ring and the coumarin ring system is 56.11 (6)°. The crystal packing is stabilized by C—HO hydrogen bonding, which forms a three-dimensional framework.

The crystal structure of the title compound, C₉H₂₀NO⁺·Cl⁻·0.33(H₃O⁺·Cl⁻), is composed of 4-hydr­oxy-2,2,6,6-tetra­methyl­piperidinium cations, hydroxonium cations and chloride anions, which are connected via O—HO, O—HCl and N—HCl hydrogen bonding. The 4-hydr­oxy-2,2,6,6-tetra­methyl­piperidinium cation and one of the two crystallographically independent chloride anions are located on a mirror plane. The hydroxonium cation is located on a threefold axis and the second crystallographically independent chloride anion is located on a sixfold rotoinversion axis. Due to symmetry, the hydroxonium cation is disordered over two positions.

In the crystal structu of the title compound, C₁₁H₂₂O₈P₂·0.5H₂O, the asymmetric unit contains two spiro­[5.5]undecane mol­ecules and one water mol­ecule. The structure is stabilized by intra- and inter­molecular C—HO and O—HO hydrogen bonds.