Crystal structure of 2-benzoylamino-N′-(4-hydroxybenzylidene)-3-(thiophen-2-yl)prop-2-enohydrazide

In the crystal a combination of N—H⋯O and asymmetric bifurcated O—H⋯(N,O) hydrogen bonds link the molecules into a three-dimensional network.


Chemical context
Compounds containing hydrazide and Schiff base functionality are of interest as examples of this class have been shown to exhibit antifungal (Singh & Dash, 1988), anti-inflammatory (Todeschini et al., 1998), antimicrobial (Pandeya et al., 1999 and antitumour activity (Desai et al., 2001).

Structural commentary
The central core of the molecule of (I), encompassing atoms N21, C3, C2, C1, N11, N12, C17 and C11, is roughly planar: the maximum deviation of any of the component atoms from the mean plane is 0.0859 (14) Å with an r.m.s. deviation of 0.049 Å . The thienyl ring and the aryl ring (C11-C16) are both nearly coplanar with the central spacer unit, making dihedral angles of 1.60 (12) and 5.35 (11) , respectively. By contrast, the aryl ring (C21-C26) is almost orthogonal to the central unit, making a dihedral angle of 80.34 (6) . The molecules of (I) exhibit no internal symmetry and they are thus conformationally chiral: the centrosymmetric space group confirms that compound (I) crystallizes as a conformational racemate. The bond distances show clearly that the bonds C2-C3 and N12-C17 are localized double bonds, consistent with the location of the H atoms as deduced from difference maps, ruling out the occurrence in the crystal of any other tautomeric forms. The non-bonded intramolecular distance O1Á Á ÁO27, 3.820 (3) Å , rules out any possibility of an intramolecular O-HÁ Á ÁO hydrogen bond.
The formation of the hydrogen-bonded network in (I) is most readily analysed in terms of simpler substructures of lower dimensionality (Ferguson et al., 1998a,b;Gregson et al., 2000). In the simplest of the substructures, molecules related by a 2 1 screw axis are linked by the three-centre hydrogen bond to form a C(8)C(11)[R 2 1 (5)] chain of rings running parallel to the [010] direction (Fig. 2). The chains of this type are linked by the N-HÁ Á ÁO hydrogen bond having atom O1 as the acceptor (Table 1) to form a two-dimensional substructure in the form of a sheet lying parallel to (001) (Fig. 3). Finally, these sheets are linked by the N-HÁ Á ÁO hydrogen bond having atom O27 as the acceptor to form a continuous framework structure (Fig. 4). This network is reinforced by a number of weak C-HÁ Á ÁO interactions (Table 1), but these are not essential to its formation.

Database survey
In the crystal structure of compound (II) (Subbulakshmi et al., 2015), a combination of N-HÁ Á ÁO and C-HÁ Á Á(arene) hydrogen bonds links the molecules into sheets; in the struc-

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were located in difference maps. The H atoms bonded to C atoms were then treated as riding atoms in geometrically idealized positions with C-H = 0.93 Å and with U iso (H) = 1.2 U eq (C

2-Benzoylamino-N′-(4-hydroxybenzylidene)-3-(thiophen-2-yl)prop-2-enohydrazide
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.