(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.

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].

4-Acetyl-piperazinium picrate.

In the title salt, C6H13N2O(+)·C6H2N3O7 (-) (systematic name: 4-acetyl-piperazin-1-ium 2,4,6-tri-nitro-phenolate), the piperazin-1-ium ring has a slightly distorted chair conformation. In the picrate anion, the mean planes of the two o-NO2 and p-NO2 groups are twisted with respect to the benzene ring by 15.0 (2), 68.9 (4) and 4.4 (3)°, respectively. In the crystal, N-H⋯O hydrogen bonds are observed, linking the ions into an infinite chain along [010]. In addition, weak cation-anion C-H⋯O inter-molecular inter-actions and a weak π-π stacking inter-action between the benzene rings of the anions, with an inter-centroid distance of 3.771 (8) Å, help to stabilize the crystal packing, giving an overall sheet structure lying parallel to (100). Disorder was modelled for one of the O atoms in one of the o-NO2 groups over two sites with an occupancy ratio of 0.57 (6):0.43 (6).

{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] .

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).

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].

[2-(Benzyl-idene-amino)-4,5,6,7-tetra-hydro-benzo[b]thio-phen-3-yl](phen-yl)methanone.

In the title compound, C22H19NOS, the cyclo-hexene ring of the tetra-hydro-benzo-thio-phenyl ring system adopts a slightly distorted half-chair conformation and is twisted slightly [7.5 (8)° for the major disorder component] from the mean plane of the thio-phene ring. The dihedral angles between the mean planes of the thio-phene ring and the phenyl rings are 65.7 (3) and 8.3 (4)°. The phenyl rings are twisted with respect to each other by 73.8 (7)°. Disorder was modeled for four C atoms of the cyclo-hexene ring over two sets of sites with an occupancy ratio of 0.659 (2):0.341 (2). In the crystal, a single weak C-H⋯O inter-action links the mol-ecules into [001] chains.

Crystal structure of N-[3-(2-chloro-benzo-yl)-5-ethyl-thio-phen-2-yl]-2-[(E)-(2-hy-droxy-benzyl-idene)amino]-acetamide.

In the title compound, C22H19ClN2O3S, the dihedral angle between the mean planes of the thio-phene ring and the chloro-phenyl and hy-droxy-phenyl rings are 70.1 (1) and 40.2 (4)°, respectively. The benzene rings are twisted with respect to each other by 88.9 (3)°. The imine bond lies in an E conformation. Intra-molecular O-H⋯N and N-H⋯O hydrogen bonds each generate S(6) ring motifs. In the crystal, weak C-H⋯O inter-actions link the mol-ecules, forming chains along the c axis and zigzag chains along the b axis, generating sheets lying parallel to (100).

Crystal structure of 1-(3-chloro-phen-yl)piperazin-1-ium picrate-picric acid (2/1).

The title salt {systematic name: bis-[1-(3-chloro-phen-yl)piperazinium 2,4,6-tri-nitro-phenolate]-picric acid (2/1)}, 2C10H14ClN2 (+)·2C6H5N3O7 (-)·C6H6N3O7, crystallized with two independent 1-(3-chloro-phen-yl)piperazinium cations, two picrate anions and a picric acid mol-ecule in the asymmetric unit. The six-membered piperazine ring in each cation adopts a slightly distorted chair conformation and contains a protonated N atom. In the picric acid mol-ecule, the mean planes of the nitro groups in the ortho-, meta-, and para-positions are twisted from the benzene ring by 31.5 (3), 7.7 (1), and 3.8 (2)°, respectively. In the anions, the dihedral angles between the benzene ring and the ortho-, meta-, and para-nitro groups are 36.7 (1), 5.0 (6), 4.8 (2)°, and 34.4 (9), 15.3 (8), 4.5 (1)°, respectively. The nitro group in one anion is disordered and was modeled with two sites for one O atom with an occupancy ratio of 0.627 (7):0.373 (7). In the crystal, the picric acid mol-ecule inter-acts with the picrate anion through a trifurcated O-H⋯O four-centre hydrogen bond involving an intra-molecular O-H⋯O hydrogen bond and a weak C-H⋯O inter-action. Weak inter-molecular C-H⋯O inter-actions are responsible for the formation of cation-anion-cation trimers resulting in a chain along [010]. In addition, weak C-H⋯Cl and weak π-π inter-actions [centroid-centroid distances of 3.532 (3), 3.756 (4) and 3.705 (3) Å] are observed and contribute to the stability of the crystal packing.

4-(Furan-2-carbon-yl)piperazin-1-ium 3,5-di-nitro-benzoate.

In the cation of the title salt, C9H13N2O2 (+)·C7H3N2O6 (-), the piperazine ring adopts a slightly distorted chair conformation. Twofold rotational disorder is exhibited by the furan ring in a 0.430 (4):0.570 (4) ratio. In the crystal, N-H⋯O hydrogen bonds link the ions into chains along [010]. Additional weak C-H⋯O inter-actions are observed, leading to a supra-molecular layer parallel to (011).

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

In the title compound, C22H18N2O3S, disorder is found in the benzoyl group (A and B), as well as for four C atoms of the cyclo-hexene ring. Two orientations were modeled in a 0.583 (5):0.417 (5) ratio. The cyclo-hexene ring is in a distorted chair conformation. The dihedral angles between the mean plane of the thio-phene ring and the 4-nitro-benzene and phenyl rings are 30.9 (8) and 64.8 (3) (A) and 62.4 (7)° (B). The mean planes of the 4-nitro-benzene and the phenyl rings are almost perpendicular to each other, with dihedral angles of 85.4 (1) (A) and 83.9 (8)° (B). An extensive array of weak C-H⋯O inter-actions consolidate mol-ecules into a three-dimensional architecture, forming chains along [001] and [010] and layers parallel to (011).

4-[Bis(4-fluoro-phen-yl)meth-yl]-1-[(2E)-3-phenyl-prop-2-en-1-yl]piperazin-1-ium 3-carb-oxy-propano-ate.

In the title salt, C(26)H(27)F(2)N(2) (+)·C(4)H(5)O(4) (-), the piperazine N atom bearing the vinylic substituent is protonated. The piperazine ring adopts a chair conformation. In ther crystal, the succinate monoanions are connected via short O-H⋯O hydrogen bonds between the carb-oxy-lic acid and carboxyl-ate groups into undulating chains extending along [001] and the flunarizinium monocations are attached to these chains via N(+)-H⋯O(-) hydrogen bonds. C-H⋯O inter-actions connect these chains into a three-dimensional network. The shortest centroid-centroid distance of 3.7256 (10) Šwas found between one of the fluorinated benzene rings and the non-fluorinated phenyl ring in the neighbouring mol-ecule related by a glide plane.

Bis{4-[(1,3-benzodioxol-5-yl)meth-yl]piperazin-1-yl}methane.

In the title compound, C25H32N4O4, both piperazine rings adopt a chair conformation. One of dioxolane ring systems is essentially planar [dihedral angle = 0.9 (2)°] while the other adopts a slightly disordered envelope conformation, the mean plane of the dioxolane ring being twisted by 3.6 (2)° from that of the benzene ring. The dihedral angle between the benzene rings is 69.9 (5)°. No classical hydrogen bonds were observed.

1-[4-(4-Hy-droxy-phen-yl)piperazin-1-yl]ethanone.

In the title compound, C12H16N2O2, the piperazine ring has a chair conformation. The dihedral angle between the mean planes of the benzene ring and the acetyl group is 48.7 (1)°. In the crystal, mol-ecules are linked via O-H⋯O hydrogen bonds, forming chains propagating along [010].

4-Methyl-N-(4-nitro-benzyl-idene)piperazin-1-amine.

In the title compound, C12H16N4O2, the piperazine ring is in a slightly distorted chair conformation. In the mol-ecule, the mean plane of the nitro group is twisted by 8.0 (3)° from that of the benzene ring. Also, the mean plane of the 2-nitro-benzyl ring is twisted slightly from that of the piperazine ring, with an N-N=C-C torsion angle of -176.24 (11)°. In the crystal, pairs of weak C-H⋯O inter-actions link the mol-ecules into dimers approximately along [010].

N-(1H-Indol-3-yl-methyl-idene)-4-methyl-piperazin-1-amine.

In the title compound, C14H18N4, the piperazine ring is in a slightly distorted chair conformation. The indole ring system is twisted from the piperazine ring, making a dihedral angle of 7.27 (11)°. In the crystal, N-H⋯N hydrogen bonds link mol-ecules into chains along [10-1].

Flunarizinium hydrogen maleate.

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 hydrogen maleate}, C26H27F2N2 (+)·C4H3O4 (-), the protonated piperazine ring is in a chair conformation. The dihedral angle between the 4-fluoro-phenyl rings is 68.2 (2)°. An intra-molecular O-H⋯O hydrogen bond occurs in the anion. In the crystal, N-H⋯O, C-H⋯O and C-H⋯F inter-actions are observed, which link the ions into [001] chains.

Crystal structure and Hirshfeld-surface analysis of a monoclinic polymorph of 2-amino-5-chloro-benzo-phenone oxime at 90†K.

The synthesis and crystal structure of a monoclinic polymorph of 2-amino-5-chloro-benzo-phenone oxime, C13H11ClN2O, are presented. The mol-ecular conformation results from twisting of the phenyl and 2-amino-5-chloro benzene rings attached to the oxime group, which subtend a dihedral angle of 80.53 (4)°. In the crystal, centrosymmetric dimers are formed as a result of pairs of strong O-H⋯N hydrogen bonds. A comparison is made to a previously known triclinic polymorph, including differences in atom-atom contacts obtained via a Hirshfeld-surface analysis.

(3-Chloro-prop-yl)triphenyl-phospho-nium bromide.

The title compound, C(21)H(21)ClP(+)Br(-), is the bromide salt of a mixed aryl-alkyl phospho-nium cation. C-P-C angles span a range of 107.20 (10)-111.18 (10)°. The non-H atoms of the 3-chloro-propyl group adopt a staggered conformation [C-C-C-Cl torsion angle: -72.0 (3)°]. In the crystal, C-H⋯Br contacts connect the entities of the title compound into a double zigzag chain along b. These chains are linked into a supra-molecular layer lying parallel to (10-1) by C-H⋯π inter-actions.