(4-Methyl-piperazin-1-yl)(2,3,4-tri-meth-oxy-benzyl-idene)amine.

In the title compound, C15H23N3O3, the piperazine ring is in a slightly distorted chair conformation and is twisted from the mean plane of the benzene ring making a dihedral angle of 14.94 (6)°. The 4-meth-oxy substituent is almost co-planar with the benzene ring [C-C-O-C torsion angle = 5.4 (1)°], while the meth-oxy groups at positions 2 and 3 [C-C-O-C torsion angles of 122.6 (4) and -66.1 (4)°, respectively] are twisted away from the mean plane of the benzene ring in anti-clinical and synclinical conformations, respectively. No classical hydrogen bonds or any weak inter-molecular inter-actions are observed in the crystal structure.

N-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-di-hydro-1H-pyrazol-4-yl)-2-(4-nitro-phen-yl)acetamide.

In the title compound, C19H18N4O4, the nitro-phenyl and phenyl rings are twisted by 67.0 (6) and 37.4 (4)°, respectively, with respect to the pyrazole ring plane [maximum deviation = 0.0042 (16) Å]. The dihedral angle between the mean planes of the phenyl rings is 59.3 (3)°. The amide group, with a C-N-C-C torsion angle of 177.54 (13)°, is twisted away from the plane of the pyrazole ring in an anti-periplanar conformation. In the crystal, N-H⋯O hydrogen bonds involving the carbonyl group on the pyrazole ring and the amide group, together with weak C-H⋯O inter-actions forming R 2 (2)(10) graph-set motifs, link the mol-ecules into chains along [100]. Additional weak C-H⋯O inter-actions involving the nitro-phenyl rings further link the mol-ecules along [001], also forming R 2 (2)(10) graph-set motifs, thereby generating (010) layers.

Flunarizinium isonicotinate.

In the cation of the title salt {systematic name: 4-[bis-(4-fluoro-phen-yl)meth-yl]-1-[(2E)-3-phenyl-prop-2-en-1-yl]piperazin-1-ium pyridine-4-carboxyl-ate}, C26H27F2N2 (+)·C6H4NO2 (-), the piperazine ring is in a slightly distorted chair conformation. The dihedral angle between the mean planes of the fluoro-substituted benzene rings is 81.9 (1)° and these benzene rings form dihedral angles of 6.5 (1) and 87.8 (1)° with the phenyl ring. In the crystal, a single N-H⋯O hydrogen bond links the cation and the anion. In addition, weak C-H⋯O hydrogen bonds and π-π stacking inter-actions involving one of the fluoro-substituted benzene rings and the phenyl ring, with a centroid-centroid distance of 3.700 (7) Å, link mol-ecules along [100].

Pyrimethaminium 2-{[4-(tri-fluoro-meth-yl)phen-yl]sulfan-yl}benzoate dimethyl sulfoxide monosolvate.

In the cation of the title solvated mol-ecular salt, C12H14ClN4 (+)·C14H8F3O2S(-)·C2H6OS [systematic name of the cation: 2,4-di-amino-5-(4-chloro-phen-yl)-6-ethyl-pyrimidin-1-ium], the dihedral angle between the planes of the pyrimidinium and 4-chloro-phenyl rings is 77.2 (5)°. In the anion, the planes of the benzene rings are twisted with respect to each other by 71.5 (5)°. Disorder was modelled for the dimethyl sulfoxide solvent mol-ecule over two set of sites in a 0.7487 (13):0.2513 (13) ratio. In the crystal, the cations are linked by inversion-generated pairs of N-H⋯N hydrogen bonds, with an R 2 (2)(8) graph-set motif. The cation donates two N-H⋯O hydrogen bonds to the anion, also generating an R 2 (2)(8) loop. These inter-actions, along with cation-solvent N-H⋯O hydrogen bonds, and cation-anion C-H⋯F, solvent-anion C-H⋯O and C-H⋯F inter-actions, result in a three-dimensional network.

4-(Pyrimidin-2-yl)piperazin-1-ium (E)-3-carb-oxy-prop-2-enoate.

In the cation of the title salt, C8H13N4 (+)·C4H3O4 (-), the piperazinium ring adopts a slightly distorteded chair conformation. In the crystal, a single strong O-H⋯O inter-molecular hydrogen bond links the anions, forming chains along the c-axis direction. The chains of anions are linked by the cations, via N-H⋯O hydrogen bonds, forming sheets parallel to (100). These layers are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional structure. In addition, there are weak π-π inter-actions [centroid-centroid distance = 3.820 (9) Å] present involving inversion-related pyrimidine rings.

5-(4-Fluoro-phen-yl)-2H-pyrazol-1-ium 2,2,2-tri-fluoro-acetate.

The title salt, C9H8FN2 (+)·C2F3O2 (-), crystallizes with two independent cations (A and B) and two independent anions (C and D) in the asymmetric unit. In the cations, the dihedral angles between the benzene and pyrazolium rings are 23.7 (3)° in cation A and 1.8 (8)° in cation B. In the crystal, each anion links to the two cations via N-H⋯O hydrogen bonds, forming a U-shaped unit with an R 4 (4)(14) ring motif. These U-shaped units stack along the a axis and are linked via C-H⋯O and C-H⋯F hydrogen bonds, forming slabs lying parallel to (100). Within the slabs there are π-π inter-actions between the pyrazolium rings [inter-centroid distance = 3.6326 (15) Å] and between the benzene rings [inter-centroid distance = 3.7244 (16) Å]. In the anions, the F atoms of the tri-fluoro-methyl groups are disordered over two sets of sites, with refined occupancy ratios of 0.58 (3):0.42, 0.540 (14):0.46 (14), and 0.55 (2):0.45 (2) for anion C, and 0.73 (5):0.27 (5), 0.63 (5):0.37 (5), and 0.57 (8):0.43 (8) for anion D.

{2-[(2-Hy-droxy-benzyl-idene)amino]-4,5,6,7-tetra-hydro-1-benzo-thio-phen-3-yl}(phen-yl)methanone.

In the title compound, C22H19NO2S, the cyclo-hexene ring adopts a slightly distorted half-chair conformation. The dihedral angles between the mean planes of the thio-phene ring and the phenyl and 2-hy-droxy-phenyl rings are 70.4 (5) and 12.1 (9)°, respectively. The phenyl and 2-hy-droxy-phenyl rings are twisted with respect to one another by 81.0 (6)°. A short intra-molecular O-H⋯N hydrogen bond is observed. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into zigzag chains diagonally along [100] .

{2-[(1H-Indol-3-yl-methyl-idene)amino]-4,5,6,7-tetra-hydro-benzo[b]thio-phen-3-yl}(phen-yl)methanone.

The title compound, C24H20N2OS, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit, in each of which the cyclo-hexene rings adopt half-chair conformations. The mean plane of the indole ring is twisted from those of the phenyl and thio-phene rings by 69.0 (7) and 8.3 (5)°, respectively, in mol-ecule A and by 65.4 (9) and 6.7 (5)°, respectively, in mol-ecule B. The dihedral angles between the mean planes of the phenyl and thio-phene rings are 63.0 (4) and 58.8 (9)° in mol-ecules A and B, respectively. In the crystal, N-H⋯O hydrogen bonds lead to the formation of an infinite chain along [101]. In addition, π-π stacking inter-actions are observed involving the thio-phene and pyrrole rings of the two mol-ecules, with a shortest inter-centroid distance of 3.468 (2) Å.

Enrofloxacinium oxalate.

The title salt, 2C19H23FN3O3 (+)·C2O4 (2-) {systematic name: bis-[4-(3-carb-oxy-1-cyclo-propyl-6-fluoro-4-oxo-1,4-di-hydro-quino-lin-7-yl)-1-ethyl-piperazin-1-ium] oxalate}, crystallizes with two independent monocations (A and B) and an oxalate dianion (C) in the asymmetric unit. The piperazinium ring in both the cations adopts a slightly disordered chair conformation. The dihedral angles between the mean planes of the cyclo-propyl ring and the 10-membered quinoline ring are 50.6 (5)° (A) and 62.2 (5)° (B). In each of the cations, a single O-H⋯O intra-molecular hydrogen bond is observed. In the crystal, the oxalate anions inter-act with the cations through N-H⋯O hydrogen bonds and weak C-H⋯O inter-actions, forming R 2 (2)(8) graph-set ring motifs. Weak C-H⋯F inter-actions along with further C-H⋯O inter-actions are observed between the cations, forming zigzag chains along [001]. In addition, π-π stacking inter-actions are observed with centroid-centroid distances of 3.5089 (13), 3.5583 (13), 3.7900 (13) and 3.7991 (13) Å.

Flupentixol tartrate.

In the title salt, C23H26F3N2OS(+)·C4H5O6 (-) [systematic name: 1-(2-hy-droxy-eth-yl)-4-[3-(2-(tri-fluoro-meth-yl)thioxanthen-9-yl-idene)prop-yl]piperazin-1-ium 3-carb-oxy-2,3-di-hydroxy-pro-pion-ate], the monoprotonated piperazine ring in the cation adopts a chair conformation, while the thio-pyran ring of the thioxanthene group has a boat conformation. The dihedral angle between the mean planes of the two outer aromatic rings of the thioxanthene groups is 31.6 (2)°. In the crystal, the cations and anions are linked via O-H⋯O, N-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds, forming chains propagating along [100]. In addition, R (2) 2(7), R (2) 2(11), R (2) 2(10) and R (2) 2(12) graph-set ring motifs involving the anions, and R (2) 2(9) graph-set ring motifs involving both the cations and anions are observed. The three F atoms of the tri-fluoro-methyl group are disordered over two sets of sites and the individual atoms were refined with occupancy ratios of 0.54 (6):0.46 (6), 0.72 (2):0.28 (2) and 0.67 (3):0.33 (3).

1-Piperonylpiperazinium picrate.

IN THE CATION OF THE TITLE SALT [SYSTEMATIC NAME: 4-(2H-1,3-benzodioxol-5-ylmeth-yl)piperazin-1-ium 2,4,6-tri-nitro-phen-o-late], C12H17N2O2 (+)·C6H2N3O7 (-), the piperazine ring adopts a slightly disordered chair conformation. The piperonyl ring system and the piperazine ring are twisted with respect to each other with an N-C-C-C torsion angle of 40.7 (2)°. In the anion, the dihedral angles between the mean planes of the nitro substituents ortho to the phenolate O atom and the mean plane of the phenyl ring are 28.8 (9) and 32.2 (8)°. In contrast, the nitro group in the para position lies much closer to the aromatic ring plane, subtending a dihedral angle of 3.0 (1)°. In the crystal, the cations and anions inter-act through N-H⋯O hydrogen bonds and a weak C-H⋯O inter-action. Weak C-H⋯O inter-actions are also observed between the anions, forming R 2 (2)(10) graph-set ring motifs. In addition, a weak centroid-centroid π-π stacking inter-action between the aromatic rings of the cation and the anion, with an inter-centroid distance of 3.7471 (9) Å, contributes to the crystal packing, resulting in a two-dimensional network along (10-1).

5-Amino-1H-pyrazol-2-ium hydrogen succinate.

In the cation of the title salt, C3H6N3 (+)·C4H5O4 (-), the protonated pyrazolium ring is planar (r.m.s. deviation = 0.012 Å). An intra-molecular C-H⋯O hydrogen bond occurs in the anion. In the crystal, N-H⋯O hydrogen bonds and a weak C-H⋯O inter-action between the cations and anions form two sets of R 2 (2)(8) graph-set ring motifs. Inter-molecular O-H⋯O hydrogen bonds between these lead to a criss-cross pattern along the b axis. In addition to the classical hydrogen bonds, a weak C-H⋯π(pyrazolium) inter-action is observed and contributes to crystal packing. All of these inter-actions link the mol-ecules into a two-dimensional supra-molecular framework parallel to (10-1).

1-Piperonylpiperazinium 4-nitro-benzoate monohydrate.

IN THE TITLE HYDRATED SALT [SYSTEMATIC NAME: 1-(1,3-benzodioxol-5-ylmeth-yl)piperazin-1-ium 4-nitro-benzoate monohydrate], C12H17N2O2 (+)·C7H4NO4 (-)·H2O, the piperazinium ring of the cation adopts a slightly distorted chair conformation. The piperonyl and piperazine rings are rotated with respect to each other with an N-C-C-C torsion angle of 45.6 (2)°. In the anion, the nitro group is almost coplanar with the adjacent benzene ring, forming a dihedral angle of only 3.9 (4)°. In the crystal, the cations, anions and water mol-ecules are linked through N-H⋯O and O-H⋯O hydrogen bonds into chains along the a axis. In addition, weaker inter-molecular C-H⋯O inter-actions are also observed within the chains. The anions form centrosymmetric couples through π-stacking inter-actions, with an inter-centroid distance of 3.681 (4) Šbetween the benzene rings.

1-Piperonylpiperazinium 4-chloro-benzoate.

In the title salt {systematic name: 1-[(1,3-benzodioxol-5-yl)meth-yl]piperazin-1-ium 4-chloro-benzoate}, C12H17N2O2 (+)·C7H4ClO2 (-), the piperazine ring adopts a slightly disordered chair conformation. The dioxole ring is in a flattened envelope conformation with the methyl-ene C atom forming the flap. The relative orientation of the piperonyl ring system and the piperazine rings is reflected in the N-C-C C torsion angle of 132.3 (1)°. In the anion, the mean plane of the carboxyl-ate group is twisted from that of the benzene ring by 14.8 (9)°. In the crystal, the components are linked by N-H⋯O and weak C-H⋯O hydrogen bonds, forming chains along [010].

3-(1H-Imidazol-1-yl)propanaminium 2-carb-oxy-4,6-di-nitro-phenolate.

In the title salt, C6H12N3 (+)·C7H3N2O7 (-), the imidazole ring is planar, with a maximum deviation of 0.0013 (14) Šfor the N attached to the propanaminium group. In the anion, a single intra-molecular O-H⋯O hydrogen bond is observed. The mean planes of the nitro groups in the anion are twisted from the benzene ring mean plane making dihedral angles of 24.7 (9) and 3.9 (6)°. In the crystal, the ammonium H atoms form N-H⋯N and N-H⋯O hydrogen bonds, resulting in an infinite chain along [111]. In addition to the classical hydrogen bonds, weak C-H⋯O and π-π [centroid-centroid distance = 3.7124 (9) Å] inter-actions are also observed, which lead to the formation a three-dimensional supramolecular structure that links the chains into layers along the bc plane.

{2-[(2-Bromo-5-meth-oxy-benzyl-idene)amino]-4,5,6,7-tetra-hydro-benzo[b]thiophen-3-yl}(phen-yl)methanone.

In the title compound, C23H20BrNO2S, disorder was modeled for the outer two C atoms of the cyclo-hexene ring over two sets of sites with an occupancy ratio of 0.580 (11):0.420 (11). Both rings have a half-chair conformation. The dihedral angles between the mean plane of the thio-phene ring and the benzene and phenyl rings are 9.2 (2) and 66.1 (2)°, respectively. The benzene and phenyl rings are inclined to each other by 74.8 (8)°. In the crystal, mol-ecules are linked by pairs of C-H⋯O hydrogen bonds, forming inversion dimers.

Crystal structure of 3-[4-(pyrimidin-2-yl)piperazin-1-ium-1-yl]butano-ate.

The title compound, C12H18N4O2, crystallizes in the zwitterionic form with protonation at the N atom of the piperazine ring bearing the carboxylate group. The piperazine ring adopts a slightly distorted chair conformation. In the crystal, N-H⋯O hydrogen bonds are observed, forming chains along [010]. The packing is consolidated by C-H⋯O inter-actions, which generate a three-dimensional network.

Two tautomers in the same crystal: 3-(4-fluoro-phen-yl)-1H-pyrazole and 5-(4-fluoro-phen-yl)-1H-pyrazole.

The title co-crystal, 3-(4-fluoro-phen-yl)-1H-pyrazole-5-(4-fluoro-phen-yl)-1H-pyrazole (1/1), C9H7FN2, crystallizes with four independent mol-ecules (A, B, C and D) in the asymmetric unit exhibiting two tautomeric forms (A and D; B and C) due to N-H proton exchange between the two N atoms of the pyrazole ring. The dihedral angles between the mean planes of the pyrazole and benzene rings are 15.6 (1), 19.8 (9), 14.0 (1) and 10.7 (7)° in mol-ecules A, B, C and D, respectively. In the crystal, N-H⋯N hydrogen bonds link the four mol-ecules in the asymmetric unit into a ring with an R 4 (4)(12) motif. Furthermore, weak C-H⋯F inter-actions link the mol-ecules into a three-dimensional network.

Crystal structure of N-(3-benzoyl-4,5,6,7-tetra-hydro-1-benzo-thio-phen-2-yl)benzamide.

In the title compound, C22H19NO2S, the cyclo-hexene ring adopts a half-chair conformation. The dihedral angles between the plane of the thio-phene ring and those of its amide- and carbonyl-bonded benzene rings are 7.1 (1) and 59.0 (2)°, respectively. An intra-molecular N-H⋯O hydrogen bond generates an S(6) ring. In the crystal, very weak aromatic π-π stacking inter-actions [centroid-centroid separation = 3.9009 (10) Å] are observed.

Crystal structures of 4-(pyrimidin-2-yl)piperazin-1-ium chloride and 4-(pyrimidin-2-yl)piperazin-1-ium nitrate.

The title salts, C8H13N4 (+)·Cl(-), (I), and C8H13N4 (+)·NO3 (-), (II), contain linked pyridinium-piperazine heterocycles. In both salts, the piperazine ring adopts a chair conformation with protonation at the N atom not linked to the other ring. In the crystal of (I), weak N-H⋯Cl inter-actions are observed, leading to zigzag chains along [100]. In the crystal of (II), both H atoms on the NH2 (+) group form bifurcated N-H⋯(O,O) hydrogen bonds. Weak C-H⋯O inter-actions are also observed. These bonds collectively link the components into infinite chains along [100].