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

Abstract

The 4-chloro- [C14H11ClN2O2, (I)], 4-bromo- [C14H10BrN2O2, (II)] and 4-diethylamino- [C18H21N3O2, (III)] derivatives of benzylidene-4-hydroxybenzohydrazide, 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 isE. 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 theaandcdirections are formedviaN—H...O and O—H...O hydrogen bonds. The molecules stack head-to-tailviaπ–π interactions involving the aromatic rings [centroid–centroid distance = 3.7622 (14) Å in (I) and 3.8021 (19) Å in (II)]. In (III), undulating two-dimensional networks extending in thebandcdirections are formedviaN—H...O and O—H...O hydrogen bonds. The molecules stack head-to-headviaπ–π interactions involving inversion-related benzene rings [centroid–centroid distances = 3.6977 (12) and 3.8368 (11) Å].