Crystal structure and Hirshfeld surface analysis of (±)-N′-(2-hydroxy-3-methoxybenzylidene)-2-(4-isobutylphenyl)propionohydrazide

The title molecule adopts a V-shaped conformation and contains an intramolecular O—H⋯N hydrogen bond. In the crystal, N—H⋯O hydrogen bonds form chains of molecules extending along the c-axis direction, which pack with normal van der Waals contacts.

The title molecule, C 21 H 26 N 2 O 3 , adopts a V-shaped conformation and is chiral at the C atom with methyl group attached at the common cut of the edges of the Vconformation and crystallizes as a racemate. It also contains an intramolecular O-HÁ Á ÁN hydrogen bond. In the crystal, N-HÁ Á ÁO hydrogen bonds form chains of molecules extending along the c-axis direction, together with normal van der Waals contacts. The roles of the various intermolecular interactions were clarified by Hirshfeld surface analysis, which reveals that the most important contributions to the crystal packing are from HÁ Á ÁH (62.6%), CÁ Á ÁH/ HÁ Á ÁC (15.8%) and OÁ Á ÁH/HÁ Á ÁO (15.3%) contacts.

Structural commentary
In the solid state, the molecule adopts a wide, V-shaped conformation ( Fig. 1) with a dihedral angle of 1.08 (11) between the mean plane of the C1-C6 ring and the chain defined by C8, C9, N1 and N2. This is likely due to the intramolecular O1-H1Á Á ÁN1 hydrogen bond (Table 1 and Fig. 1). The dihedral angle between the latter chain and the mean plane of the C12-C17 ring is 59.34 (6) . There is one stereogenic center in the racemic title compound and the chirality of the C10 atom is S in the chosen asymmetric unit. All bond distances and angles appear as expected.

Supramolecular features and Hirshfeld surface analysis
In the crystal, N2-H2Á Á ÁO2 and weaker N2-H2Á Á ÁO1 hydrogen bonds (Table 1) form chains of molecules extending along the c-axis direction (Fig. 2). The molecular packing is provided by normal van der Waals interactions between chains.
Hirshfeld surfaces and their related two-dimensional fingerprint plots were generated using CrystalExplorer17.5 (Turner et al., 2017) to visually represent the intermolecular interactions in the crystal structure of the title compound. The Hirshfeld surface plotted over d norm in the range À0.3801 to +1.4738 a.u. is shown in Fig. 3. The interactions shown in Tables 1 and 2 are important in the molecular packing of the title compound.

Figure 2
A portion of one chain viewed along the b-axis with the O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds depicted by dashed lines and non-interacting hydrogen atoms omitted for clarity.

Figure 1
The title molecule with labeling scheme and 30% probability level ellipsoids. The intramolecular O-HÁ Á ÁN hydrogen bond is depicted by a dashed line. Only the major component of the disorder is shown.   In (I), three independent molecules in the asymmetric unit and two water molecules of crystallization are observed. The three unique organic molecules differ in the conformations of the substituents on the pyrazole ring. In the crystal, extensive O-HÁ Á ÁO, O-HÁ Á ÁN, N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonding generates a three-dimensional network and C-HÁ Á Á interactions are also observed. Compounds (II) and (III) crystallize with two molecules in the asymmetric unit, with generally similar conformations that approximate to Lshapes. The packing for (II) features short C-HÁ Á ÁO interactions arising from the C-H adjacent to the cyanide group and C-HÁ Á ÁN c (c = cyanide) links arising from the methine groups to generate [110] double chains. Weak C-HÁ Á Á interactions interlink the chains into a three-dimensional network. The packing for (III) features numerous C-HÁ Á ÁO and C-HÁ Á Á interactions arising from different donor groups to generate a three-dimensional network. In (IV), the molecular conformation is influenced by intramolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds. In the crystal, N-HÁ Á ÁO hydrogen bonds plus C-HÁ Á Á andstacking interactions lead to the formation of chains extending in the aaxis direction. The chains are linked by complementary pairs of C-HÁ Á Á interactions. Compound (V) has four independent molecules in the asymmetric unit. In the crystal, N-H-O hydrogen bonds involving the hydrazide and acetyl groups, which form R 2 2 (18) ring motifs, link the molecules into dimers, which form columns along the [010] plane. In the crystal of (VI), the molecules are linked by C-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds, as well as weak C-HÁ Á Á contacts, forming a three-dimensional supramolecular architecture.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms attached to carbon were placed in calculated positions (C-H = 0.95-1.00 Å ) and were included as riding contributions with isotropic displacement parameters 1.2-1.5 times those of the attached atoms. Those attached to nitrogen and to oxygen were placed in locations derived from a difference map and refined freely with DFIX 0.91 0.01 and DFIX 0.84 0.01 instructions, respectively. The atoms of the propane group are disordered over two sets of sites with an occupancy ratio of 0.929 (3)    program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/1 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2020).

Special details
Experimental. The diffraction data were obtained from 15 sets of frames, each of width 0.5° in ω or φ, collected with scan parameters determined by the "strategy" routine in APEX4. The scan time was 10 sec/frame. 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.