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).

Different weak inter-actions in the crystals of three isomeric (E)-N-methyl-N'-(nitro-benzyl-idene)-2-(thio-phen-2-yl)acetohydrazides.

The crystal structures of three isomeric (E)-N-methyl-N'-(nitro-benzyl-idene)-2-(thio-phen-2-yl)acetohydrazides (formula C14H13N3O3S) are described, with the nitro group in ortho, meta and para positions in the benzene ring. In each crystal structure, mol-ecules are linked by various weak inter-actions (C-H⋯O and C-H⋯π bonds, and π-π stacking), leading to three-dimensional networks in each case, but with little similarity between them.

Different hydrogen-bonded chains in the crystal structures of three alkyl N-[(E)-1-(2-benzyl-idene-1-methyl-hydrazin-yl)-3-hy-droxy-1-oxopropan-2-yl]carbamates.

The crystal structures of three methyl-ated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopro-pan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopro-pan-2-yl]carbamate, C16H23N3O4. One of them shows that an unexpected racemization has occurred during the mild-condition methyl-ation reaction. In each crystal structure, the mol-ecules are linked into chains by O-H⋯O hydrogen bonds, but with significant differences between them.