1-Piperonylpiperazinium picrate

In the cation of the title salt [systematic name: 4-(2H-1,3-benzodioxol-5-ylmeth­yl)piperazin-1-ium 2,4,6-tri­nitro­phen­o­late], 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 inter­act through N—H...O hydrogen bonds and a weak C—H...O inter­action. Weak C—H...O inter­actions are also observed between the anions, forming R₂²(10) graph-set ring motifs. In addition, a weak centroid–centroid π–π stacking inter­action between the aromatic rings of the cation and the anion, with an inter­centroid distance of 3.7471 (9) Å, contributes to the crystal packing, resulting in a two-dimensional network along (10-1).

1-Piperonylpiperazinium 4-nitro­benzoate monohydrate

In the title hydrated salt [systematic name: 1-(1,3-benzodioxol-5-ylmeth­yl)piperazin-1-ium 4-nitro­benzoate 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 mol­ecules are linked through N—H...O and O—H...O hydrogen bonds into chains along the a axis. In addition, weaker inter­molecular C—H...O inter­actions are also observed within the chains. The anions form centrosymmetric couples through π-stacking inter­actions, with an inter­centroid distance of 3.681 (4) Å between the benzene rings.

1-Piperonylpiperazinium 4-chloro­benzoate

In the title salt {systematic name: 1-[(1,3-benzodioxol-5-yl)meth­yl]piperazin-1-ium 4-chloro­benzoate}, C₁₂H₁₇N₂O₂⁺·C₇H₄ClO₂⁻, the piperazine ring adopts a slightly disordered chair conformation. The dioxole ring is in a flattened envelope conformation with the methyl­ene C atom forming the flap. The relative orientation of the piperonyl ring system and the piperazine rings is reflected in the N—C—C[pdbond]C torsion angle of 132.3 (1)°. In the anion, the mean plane of the carboxyl­ate 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-[(2-Hy­droxy­benzyl­idene)amino]-4,5,6,7-tetra­hydro-1-benzo­thio­phen-3-yl}(phen­yl)methanone

In the title compound, C₂₂H₁₉NO₂S, the cyclo­hexene ring adopts a slightly distorted half-chair conformation. The dihedral angles between the mean planes of the thio­phene ring and the phenyl and 2-hy­droxy­phenyl rings are 70.4 (5) and 12.1 (9)°, respectively. The phenyl and 2-hy­droxy­phenyl rings are twisted with respect to one another by 81.0 (6)°. A short intra­molecular O—H...N hydrogen bond is observed. In the crystal, weak C—H...O inter­actions link the mol­ecules into zigzag chains diagonally along [100] .

(4-Methyl­piperazin-1-yl)(2,3,4-tri­meth­oxy­benzyl­idene)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-meth­oxy substituent is almost co-planar with the benzene ring [C-C-O-C torsion angle = 5.4 (1)°], while the meth­oxy 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 anti­clinical and synclinical conformations, respectively. No classical hydrogen bonds or any weak inter­molecular inter­actions are observed in the crystal structure.

[2-(Benzyl­idene­amino)-4,5,6,7-tetra­hydro­benzo[b]thio­phen-3-yl](phen­yl)methanone

In the title compound, C₂₂H₁₉NOS, the cyclo­hexene ring of the tetra­hydro­benzo­thio­phenyl 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 thio­phene ring. The dihedral angles between the mean planes of the thio­phene 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 cyclo­hexene 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 inter­action links the mol­ecules into [001] chains.

Flunarizinium isonicotinate

In the cation of the title salt {systematic name: 4-[bis­(4-fluoro­phen­yl)meth­yl]-1-[(2E)-3-phenyl­prop-2-en-1-yl]piperazin-1-ium pyridine-4-carboxyl­ate}, 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 inter­actions involving one of the fluoro-substituted benzene rings and the phenyl ring, with a centroid–centroid distance of 3.700 (7) Å, link mol­ecules along [100].

4-(Furan-2-carbon­yl)piperazin-1-ium 3,5-di­nitro­benzoate

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 inter­actions are observed, leading to a supra­molecular layer parallel to (011).

4-Acetyl­piperazinium picrate

In the title salt, C₆H₁₃N₂O⁺·C₆H₂N₃O₇⁻ (systematic name: 4-acetyl­piperazin-1-ium 2,4,6-tri­nitro­phenolate), 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 inter­molecular inter­actions and a weak π–π stacking inter­action 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-[(4-Nitro­benzyl­idene)amino]-4,5,6,7-tetrahydro-1-benzo­thio­phen-3-yl}(phen­yl)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 cyclo­hexene ring. Two orientations were modeled in a 0.583 (5):0.417 (5) ratio. The cyclo­hexene ring is in a distorted chair conformation. The dihedral angles between the mean plane of the thio­phene ring and the 4-nitro­benzene and phenyl rings are 30.9 (8) and 64.8 (3) (A) and 62.4 (7)° (B). The mean planes of the 4-nitro­benzene 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 inter­actions consolidate mol­ecules into a three-dimensional architecture, forming chains along [001] and [010] and layers parallel to (011).