Fifteen 4-(2-methoxyphenyl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. In the isostructural 4-chlorobenzoate and 4-bromobenzoate salts, C11H17N2O+·C7H4ClO2 − (I) and C11H17N2O+·C7H4BrO2 − (II), and the 4-iodobenzoate salt C11H17N2O+·C7H4IO2 − (III), the ions are linked by N—H...O hydrogen bonds, forming centrosymmetric R 4 4(12) four-ion aggregates; a similar aggregate is formed in the 2-chlorobenzoate salt (V), isomeric with (I). In the 2-fluorobenzoate salt C11H17N2O+·C7H4FO2 − (IV), and the isomorphous pair of salts, the 2-bromobenzoate (VI), isomeric with (II) and 2-iodobenzoate (VII), isomeric with (III), N—H...O and C—H...π(arene) interactions link the components into three-dimensional arrays. Four-ion R 4 4(12) aggregates are also found in the 2-methylbenzoate, 4-aminobenzoate and 4-nitrobenzoate salts, C11H17N2O+·C8H7O2 − (VIII), C11H17N2O+·C7H6NO2 − (IX) and C11H17N2O+·C7H4NO4 − (X), but those in (IX) are linked into complex sheets by an additional N—H...O hydrogen bond. In the 3,5-dinitrobenzoate salt, C11H17N2O+·C7H3N2O6 −·2H2O (XI), N—H...O and O—H...O hydrogen bonds link the components into a complex ribbon structure. In the picrate salt, C11H17N2O+·C6H2N3O7 − (XII), the four-ion aggregates are linked into chains of rings by C—H...O hydrogen bonds. In the hydrogen maleate salt, C11H17N2O+·C4H3O4 − (XIII), two- and three-centre hydrogen bonds link the ions into a ribbon structure while both anions contain very short but asymmetric O—H...O hydrogen bonds, having O...O distances of 2.4447 (16) and 2.4707 (17) Å. O—H...O Hydrogen bonds link the anions in the hydrogen fumarate salt (XIV), isomeric with (XIII), into chains that are linked into sheets via N—H...O hydrogen bonds. In the hydrogen (2R,3R)-tartrate salt, C11H17N2O+·C4H5O6 −·1.698H2O (XV), the anions are linked into sheets by O—H...O hydrogen bonds. Comparisons are made with the structures of some related compounds.

The structures are reported for five salts formed by reactions between N-(4-fluorophenyl)piperazine and aromatic acids. In 4-(4-fluorophenyl)piperazin-1-ium 2-fluorobenzoate monohydrate, C10H14FN2 +·C7H4FO2 −·H2O, (I), the components are linked by a combination of N—H...O and O—H...O hydrogen bonds to form a chain of alternating R 4 6(12) and R 6 6(16) rings. The ionic components of 4-(4-fluorophenyl)piperazin-1-ium 2-bromobenzoate 0.353-hydrate, C10H14FN2 +·C7H4BrO2 −·0.353H2O, (II), are linked by N—H...O hydrogen bonds to form a centrosymmetric four-ion aggregate containing an R 4 4(12) motif, and these aggregates are linked into a molecular ladder by a single C—H...π(arene) hydrogen bond. 4-(4-Fluorophenyl)piperazin-1-ium 2-iodobenzoate, C10H14FN2 +·C7H4IO2 −, (III), crystallizes with Z′ = 2 in space group P\overline{1}: the four independent ions are linked by N—H...O hydrogen bonds to form a non-centrosymmetric aggregate again containing an R 4 4(12) motif, and aggregates of this type are linked into a ribbon by a combination of C—H...O and C—H...π(arene) hydrogen bonds. The anion in 4-(4-fluorophenyl)piperazin-1-ium 2,4,6-trinitrophenolate, C10H14FN2 +·C6H2N3O7 −, (IV), shows clear evidence of extensive electronic delocalization from the phenolate O atom into the adjacent ring. The ions are linked by a combination of two-centre N—H...O and three-centre N—H...(O)2 hydrogen bonds to form centrosymmetric four-ion aggregates containing three types of ring. The ions in 4-(4-fluorophenyl)piperazin-1-ium 3,5-dinitrobenzoate, C10H14FN2 +·C7H3N2O6 −, (V), are again linked by N—H...O hydrogen bonds to form centrosymmetric R 4 4(12) aggregates, which are themselves linked by a C—H...π(arene) hydrogen bond to form sheets, the stacking of which leads to the formation of narrow channels, containing disordered and/or mobile solvent entities. Comparisons are made with some related structures.

Three salts containing the 4-(4-fluorophenyl)piperazin-1-ium cation have been prepared and structurally characterized. In 4-(4-fluorophenyl)piperazin-1-ium 2-hydroxy-3,5-dinitrobenzoate, C10H14FN2 +·C7H3N2O7 −, (I), the anion contains an intramolecular O—H...O hydrogen bond, and it has a structure similar to that of the picrate ion. The cations and anions are linked into [001] chains of rings by a combination of two three-centre N—H...(O)2 hydrogen bonds. The anion in 4-(4-fluorophenyl)piperazin-1-ium hydrogen oxalate, C10H14FN2 +·C2HO4 −, (II), is planar, and the cations and anions are linked into (100) sheets by multiple hydrogen bonds including two-centre N—H...O, three-centre N—H...(O)2, O—H...O, C—H...O and C—H...π(arene) types. In 4-(4-fluorophenyl)piperazin-1-ium hydrogen (2R,3R)-tartrate monohydrate, C10H14FN2 +·C4H5O6 −·H2O, (III), the anion exhibits an approximate non-crystallographic twofold rotation symmetry with antiperiplanar carboxyl groups. A combination of eight hydrogen bonds, encompassing two- and three-centre N—H...O systems, O—H...O and C—H...π(arene) types, link the independent components into a three-dimensional framework. Comparisons are made with some related structures.

In the title compound, C18H18N4O6, the piperazine ring adopts a chair conformation, the amidic N atom is planar (sum of angles = 360°) and the non-amidic N atom is pyramidal (343°). There are no hydrogen bonds of any kind in the crystal, but the molecules are linked by two independent π(nitrobenzene)...π(methoxybenzene) stacking interactions to form π-stacked sheets with inter-centroid separations of 3.8444 (12) and 3.9197 (12) Å.

Two new N-{[4-(3-aryl-4-sydnonylideneamino)-5-sulfanylidene-1H-1,2,4-triazol-3-yl]methyl}benzamides have been prepared by acid-promoted condensation reactions between 3-aryl-4-formylsydnones and N-[(4-amino-5-sulfanylidene-1H-1,2,4-triazol-3-yl)methyl]benzamide, and both have been crystallized as ethanol monosolvates. N-{[4-(3-Phenyl-4-sydnonylideneamino)-5-sulfanylidene-1H-1,2,4-triazol-3-yl]methyl}benzamide ethanol monosolvate, C19H15N7O3S·C2H6O (I), and N-({4-[3-(4-methylphenyl)-4-sydnonylideneamino]-5-sulfanylidene-1H-1,2,4-triazol-3-yl}methyl)benzamide ethanol monosolvate, C20H17N7O3S·C2H6O (II), differ only in the presence of a methyl group for (II) instead of a hydrogen atom for (I), and in both of them the ethanol component is disordered over two sets of atomic sites having occupancies of 0.836 (6) and 0.164 (6) in (I), and 0.906 (6) and 0.094 (6) in (II). Combinations of O—H...O and N—H...O hydrogen bonds link the molecules into cyclic, centrosymmetric four-molecule aggregates. Comparisons are made with the structures of some related compounds.