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The mol­ecular and crystal structures of two isomeric bis­(iodo­meth­yl)benzene derivatives are reported. A comparison is made of the inter­molecular contacts stabilizing the packing in the two closely related systems., The isomeric derivatives 1,2-bis­(iodo­meth­yl)benzene, (I), and 1,3-bis­(iodo­meth­yl)benzene (II), both C8H8I2, were prepared by metathesis from their di­bromo analogues. The ortho-derivative, (I), lies about a crystallographic twofold axis that bis­ects the C—C bond between the two iodo­methyl substituents. The packing in (I) relies solely on C—H⋯I hydrogen bonds supported by weak parallel slipped π–π stacking inter­actions [inter-centroid distance = 4.0569 (11) Å, inter-planar distance = 3.3789 (8) Å and slippage = 2.245 Å]. While C—H⋯I hydrogen bonds are also found in the packing of (II), type II, I⋯I halogen bonds [I⋯I = 3.8662 (2) Å] and C—H⋯π contacts feature prominently in stabilizing the three-dimensional structure.

The title compound, C13H9N3, has three symmetry-independent molecules in the asymmetric unit. The dihedral angles between the naphthyridine ring system and the pyridine group are in the range 3.927 (4)–7.362 (4)°. In the crystal, C—H...N interactions and aromatic π–π stacking [centroid–centroid distances = 3.5755 (7) and 3.6544 (7) Å] generate a three-dimensional network.

The mol­ecular and crystal structure of N-{4-[(6-chloro­pyridin-3-yl)meth­oxy]phen­yl}-2,6-di­fluoro­benzamide is reported. The crystal packing is stabilized by N—H⋯N, C—H⋯O, C—H⋯F and C—H⋯π hydrogen bonds supplemented by offset π–π stacking inter­actions., In the title compound, C19H13ClF2N2O2, the conformation of the N—H bond in the amide segment is anti to the C=O bond. The mol­ecule is not planar, with dihedral angles between the central benzene ring and the outer benzene and pyridyl rings of 73.35 (7) and 81.26 (6)°, respectively. A weak intra­molecular C—H⋯O hydrogen bond occurs. In the crystal, N—H⋯N, C—H⋯O and C—H⋯F hydrogen bonds lead to the formation of dimers. The N—H⋯N inversion dimers are linked by π–π contacts between adjacent pyridine rings [centroid–centroid = 3.8541 (12) Å] and C—H⋯π inter­actions. These contacts combine to stack the mol­ecules along the a axis.

Between the tosyl­ate anions and the octa­hedral complex cations consisting of FeII, four aqua and two N-bound 2-chloro­pyrazine ligands, weak O—H⋯O as well as π–π inter­actions play important roles in the mol­ecular self-assembly, resulting in the formation of a three-dimensional structure., The title salt, [FeII(C4H3ClN2)2(H2O)4](C7H7O3S)2, contains a complex cation with point group symmetry 2/m. The high-spin FeII cation is hexa­coordinated by four symmetry-related water and two N-bound 2-chloro­pyrazine mol­ecules in a trans arrangement, forming a distorted FeN2O4 octa­hedron. The three-dimensional supra­molecular structure is supported by inter­molecular O—H⋯O hydrogen bonds between the complex cations and tosyl­ate anions, and additional π–π inter­actions between benzene and pyrazine rings. The methyl H atoms of the tosyl­ate anion are equally disordered over two positions.

The title compound, C14H11N3O2, crystallizes with two molecules in the asymmetric unit. The indazole ring system and the nitro group are nearly coplanar, with the largest deviations from the mean plane being 0.070 (4) Å in one molecule and 0.022 (3) Å in the second. The dihedral angle between the mean plane through the phenyl ring and the mean plane of the indazole ring system is of 23.24 (18)° in the first molecule and 26.87 (18)° in the second. In the crystal, molecules are linked by two C—H...O hydrogen bonds, forming linear zigzag tapes running along thec-axis direction, and by π–π stacking of molecules along thebaxis, generating a three-dimensional structure.

In the title compound, C23H19N3O2, the terpyridine unit has a dimethoxyphenyl substituent at the 4-position of the central pyridyl ring. The three pyridyl rings are in atransoidconformation with respect to the interannular C—C bonds. In addition, the pendant dimethoxyphenyl substituent is almost coplanar with the terpyridyl unit; the dihedral angle between the central pyridyl ring and the benzene ring is 7.14 (11)°, which is much smaller than that found in the structural isomer with a 2,5-dimethoxyphenyl substituent. The C—C and C—N bond lengths within the aromatic rings are normal. One of the terminal pyridyl rings is disordered over two sets of sites with an occupancy ratio of 0.744 (7):0.256 (7). The orientation of the two methoxy groups at the 3- and 4-positions is such that the methyl groups point away from each other in opposite directions. In the crystal structure, C–H...N hydrogen bonds form chains alongbwhile C—H...O contacts form inversion dimers, creating double chains. These combine with C—H...π contacts and π...π interactions, with a centroid-centroid distance of 3.858 (4) Å, to stack molecules along theb-axis direction.

The complete molecule of the title compound, C14H8N2, is generated by a twofold rotation axis located at the midpoint of the biphenyl C—C bond. The dihedral angle between the symmetry-related phenyl rings is 46.16 (3)°. In the crystal, molecules are linked by slipped parallel π–π interactions [centroid–centroid distance = 3.9451 (7) Å, normal distance = 3.6293 (5) Å, slippage 1.547 Å], forming columns along theb-axis direction.