4-(Pyrimidin-2-yl)piperazin-1-ium (E)-3-carboxyprop-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 intermolecular 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 interactions [centroid–centroid distance = 3.820 (9) Å] present involving inversion-related pyrimidine rings

Pyrimethaminium 2-{[4-(trifluoromethyl)phenyl]sulfanyl}benzoate dimethyl sulfoxide monosolvate

In the cation of the title solvated molecular salt, C12H14ClN4+·C14H8F3O2S−·C2H6OS [systematic name of the cation: 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium], the dihedral angle between the planes of the pyrimidinium and 4-chlorophenyl 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 molecule 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 R22(8) graph-set motif. The cation donates two N—H...O hydrogen bonds to the anion, also generating an R22(8) loop. These interactions, along with cation–solvent N—H...O hydrogen bonds, and cation–anion C—H...F, solvent–anion C—H...O and C—H...F interactions, result in a three-dimensional network

Two tautomers in the same crystal: 3-(4-fluorophenyl)-1H-pyrazole and 5-(4-fluorophenyl)-1H-pyrazole

The title co-crystal, 3-(4-fluorophenyl)-1H-pyrazole–5-(4-fluorophenyl)-1H-pyrazole (1/1), C9H7FN2, crystallizes with four independent molecules (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 molecules A, B, C and D, respectively. In the crystal, N—H...N hydrogen bonds link the four molecules in the asymmetric unit into a ring with an R44(12) motif. Furthermore, weak C—H...F interactions link the molecules into a three-dimensional network

2-[4-(Trifluoromethyl)phenylsulfanyl]benzoic acid

In the title compound, C14H9F3O2S, the dihedral angle between the mean planes of the benzene rings is 88.7 (2)°. The carboxylic acid group is twisted by 13.6 (7)° from the mean plane of its attached aromatic ring. One of the F atoms of the trifluoromethyl group is disordered over two sites in a 0.61 (7):0.39 (7) ratio. In the crystal, inversion dimers linked by pairs of O—H...O hydrogen bonds generate R22(8) loops. Weak C—H...F interactions are also observed

Enrofloxacinium oxalate

The title salt, 2C19H23FN3O3+·C2O42− {systematic name: bis-[4-(3-carboxy-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinolin-7-yl)-1-ethylpiperazin-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 cyclopropyl 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 intramolecular hydrogen bond is observed. In the crystal, the oxalate anions interact with the cations through N—H...O hydrogen bonds and weak C—H...O interactions, forming R22(8) graph-set ring motifs. Weak C—H...F interactions along with further C—H...O interactions are observed between the cations, forming zigzag chains along [001]. In addition, π–π stacking interactions are observed with centroid–centroid distances of 3.5089 (13), 3.5583 (13), 3.7900 (13) and 3.7991 (13) Å

6-Chloro-2-chloromethyl-4-phenylquinazoline 3-oxide

In the title compound, C15H10Cl2N2O, the dihedral angle between the mean planes of the phenyl ring and the 10-membered quinazoline ring is 63.3 (4)°. In the crystal, pairs of weak C—H...O interactions link the molecules into centrosymmetric dimers, forming R22(10) graph-set ring motifs. In addition, weak π–π stacking interactions [minimum centroid–centroid separation = 3.6810 (8) Å] are observed, which contribute to the formation of a supramolecular assembly in the packing array