Crystal structures of three ortho-substituted N-acyl-hydrazone derivatives

To explore the effect of the nature of substitutions on the structural parameters and hydrogen-bond inter-actions in N-acyl-hydrazone derivatives, the crystal structures of three ortho-substituted N-acyl-hydrazone derivatives, namely (E)-N-{2-[2-(2-chloro-benzyl-idene)hydrazin-yl]-2-oxoeth-yl}-4-methyl-benzene-sulfon-amide, C₁₆H₁₆ClN₃O₃S (I), (E)-N-{2-[2-(2-methyl-benzyl-idene)hydrazin-yl]-2-oxoeth-yl}-4-methyl-benzene-sulfonamide, C₁₇H₁₉N₃O₃S (II), and (E)-N-{2-[2-(2-nitro-benzyl-idene)hydrazin-yl]-2-oxoeth-yl}-4-methyl-benzene-sulfonamide, C₁₆H₁₆N₄O₅S (III), have been determined. The structures of the three compounds display similar mol-ecular conformations and hydrogen-bond patterns. The hydrazone part of the mol-ecule, C-C-N-N=C, is almost planar in all the compounds, with the C-C-N-N and C-N-N=C torsion angles being 179.5 (3) and 177.1 (3)°, respectively, in (I), -179.4 (2) and -177.1 (3)° in (II) and -179.7 (2) and 173.4 (2)° in (III). The two phenyl rings on either side of the chain are approximately parallel to each other. In the crystal, the mol-ecules are linked to each other via N-H⋯O hydrogen bonds, forming ribbons with R₂²(8) and R₂²(10) ring motifs. The introduction of electron-withdrawing groups (by a chloro or nitro group) to produce compounds (I) or (III) results in C-H⋯O hydrogen-bonding inter-actions involving the sulfonyl O atoms of adjacent ribbons, forming layers parallel to the ab plane in (I) or a three-dimensional network in (III). In (III), one O atom of the nitro group is disordered over two orientations with refined occupancy ratio of 0.836 (12):0.164 (12).