Experimental and computational evidence for stabilising parallel, offset π[C(O)N(H)NC]⋯π(phenyl) interactions in acetohydrazide derivatives

Stabilising π[C(O)N(H)NC]⋯π(phenyl) interactions are described.

The crystal structure of N′-(2-chloro-6-hydroxybenzylidene)thiophene-2-carbohydrazide monohydrate, C12H11ClN2O3S

C12H11ClN2O3S, monoclinic, P21/n (no. 14), a = 4.7305(8) Å, b = 21.252(4) Å, c = 13.134(2) Å, β = 96.286(2)°, Z = 4, V = 1312.5(4) Å3, R gt (F) = 0.1002, wR ref (F 2) = 0.1118, T = 296 K.

Different packing motifs of isomeric (E)-N'-(halo-phenyl-methyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazides controlled by C-H⋯O inter-actions

The crystal structures of three isomeric (E)-N'-(chloro-phenyl-methyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazides (C14H13ClN2OS) are described, with the Cl atom in ortho (I), meta (III) and para (IV) positions in the benzene ring. The ortho-bromo derivative (II) (C14H13BrN2OS), which is isostructural with its chloro congener (I), is also reported. Mol-ecules (I)-(III) have similar conformations, which approximate to l-shapes, as indicated by their N-C-C-Ct (t = thio-phene) torsion angles of -90.1 (3), -91.44 (18) and -90.7 (9)°, respectively. The conformation of (IV) is different, with an equivalent torsion angle of -170.75 (11)° corresponding to a more extended shape for the mol-ecule. The thio-phene ring in each structure features 'flip' rotational disorder. The packing for (I) and (II) features inversion dimers, linked by pairs of C-H⋯O inter-actions, which generate R22(14) loops. In the crystal of (III), [010] C(8) chains arise, with adjacent mol-ecules linked by pairs of C-H⋯O hydrogen bonds. The packing for (IV) features unusually short C-H⋯O inter-actions arising from an H atom attached to the benzene ring (H⋯O = 2.18 Å), which lead to C(9) [301] chains. Hirshfeld fingerprint percentage contact contributions are similar for the four title compounds.

Crystal structures and Hirshfeld surfaces of differently substituted (E)-N'-benzyl-idene-N-methyl-2-(thio-phen-2-yl)acetohydrazides

The syntheses and crystal structures of (E)-N'-(3-cyano-benzyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazide, C15H13N3OS, (I), and (E)-N'-(4-meth-oxy-benzyl-idene)-N-methyl-2-(thio-phen-2-yl)acetohydrazide, C15H16N2O2S, (II), with different substituents in the meta and para position of the benzene ring are described. Compounds (I) and (II) both crystallize with two mol-ecules in the asymmetric unit, with generally similar conformations [r.m.s. overlay fits for (I) and (II) of 0.334 and 0.280 Å, respectively] that approximate to L-shapes. The thio-phene rings in (I) are well ordered, whereas those in (II) exhibit 'flip' rotational disorder [occupancies 0.662 (2) and 0.338 (2) for mol-ecule 1, and 0.549 (3) and 0.451 (3) for mol-ecule 2]. The packing for (I) features short C-H⋯O inter-actions arising from the C-H grouping adjacent to the cyanide group and C-H⋯Nc (c = cyanide) links arising from the methine groups to generate [110] double chains. Weak C-H⋯π inter-actions inter-link the chains into a three-dimensional network. The packing for (II) features numerous C-H⋯O and C-H⋯π inter-actions arising from different donor groups to generate a three-dimensional network. Hirshfeld fingerprint plots indicate significant differences in the percentage contact surfaces for (I) and (II).

N'-[(1E)-(5-Nitro-furan-2-yl)methyl-idene]thio-phene-2-carbohydrazide: crystal structure and Hirshfeld surface analysis

In the title carbohydrazide, C10H7N3O4S, the dihedral angle between the terminal five-membered rings is 27.4 (2)°, with these lying to the same side of the plane through the central CN2C(=O) atoms (r.m.s. deviation = 0.0403 Å), leading to a curved mol-ecule. The conformation about the C=N imine bond [1.281 (5) Å] is E, and the carbonyl O and amide H atoms are anti. In the crystal, N-H⋯O hydrogen bonds lead to supra-molecular chains, generated by a 41 screw-axis along the c direction. A three-dimensional architecture is consolidated by thienyl-C-H⋯O(nitro) and furanyl-C-H⋯O(nitro) inter-actions, as well as π-π inter-actions between the thienyl and furanyl rings [inter-centroid distance = 3.515 (2) Å]. These, and other, weak inter-molecular inter-actions, e.g. nitro-N-O⋯π(thien-yl), have been investigated by Hirshfeld surface analysis, which confirms the dominance of the conventional N-H⋯O hydrogen bonding to the overall mol-ecular packing.