(E)-N′-(4-Chlorobenzylidene)-,(E)-N′-(4-bromobenzylidene)- and (E)-N′-[4-(diethylamino)benzylidene]-derivatives of 4- hydroxybenzohydrazide

Article abstract of DOI:10.1107/S0108270112038462

The 4-chloro- [C₁₄H₁₁ClN₂O₂, (I)], 4-bromo- [C₁₄H₁₀BrN₂O₂, (II)] and 4-diethyl-amino- [C₁₈H₂₁N₃O₂, (III)] derivatives of benzyl-idene-4-hy-droxy-benzo-hydrazide, all crystallize in the same space group (P2₁/c), (I) and (II) also being isomorphous. In all three compounds, the conformation about the C=N bond is E. The molecules of (I) and (II) are relatively planar, with dihedral angles between the two benzene rings of 5.75 (12) and 9.81 (17)°, respectively. In (III), however, the same angle is 77.27 (9)°. In the crystal structures of (I) and (II), two-dimensional slab-like networks extending in the a and c directions are formed via N - H...O and O - H...O hydrogen bonds. The molecules stack head-to-tail via π-π interactions involving the aromatic rings [centroid-centroid distance = 3.7622 (14) A in (I) and 3.8021 (19) A in (II)]. In (III), undulating two-dimensional networks extending in the b and c directions are formed via N - H...O and O - H...O hydrogen bonds. The molecules stack head-to-head via π-π interactions involving inversion-related benzene rings [cen-troid-centroid distances = 3.6977 (12) and 3.8368 (11) A].