N-[4-(Phenyliminomethyl)phenyl]acetamide 0.67-hydrate

The title compound, C15H14N2O·0.67H2O, was prepared by the reaction of 4-acetoaminebenzaldehyde and aniline. The asymmetric unit contains six organic molecules and four water molecules. The dihedral angles between the aromatic ring planes in each organic molecule vary from 42.4 (2) to 53.8 (2)°. In the crystal, an extensive network of intermolecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the molecules into [010] chains.

In addition, Schiff base metal complexes can be effective as stereospecific catalysts for oxidation (Kureshy et al., 1999), reduction (Aoyama et al., 1986) and other transformations in organic and inorganic chemistry. The title Schiff base compound was synthesized from 4-acetoaminebenzaldehyde and aniline as a potential ligand for the preparation of transition metal complexes.
The asymmetric unit contains six molecules of 4-acetylaminobenzylidine aniline (I) and four water molecules. Figure 1 shows a plot of one of the molecules of (I). The dihedral angles between the two aromatic ring planes in each molecule of (I) vary from 42.4 (2) to 53.8 (2)° ( Table 2). The six molecules in the asymetric unit are arranged in pairs, one above the other.
There are possible π-stacking interactions between the carbonyl group of each molecule in the pair with the central phenyl group of the molecule above or below it, with carbonyl O and C atoms to aromatic ring distances varying from 3.002 (4) to 3.421 (4) Å and 3.191 (6) to 3.492 (6) Å, respectively (Table 3, Figure 2). The paired molecules are further linked to one another by O-H···N and O-H···O hydrogen bonds from two water molecules, one at each side of the pair (Table 1, Figure 2). Each pair of molecules is linked to adjacent pairs on either side by N-H···O contacts (Table 3), either to water O atoms (i.e. the N1-H1···O1S, N3-H3···O2S, N5-H5···O4S and N7-H7···O3S contacts) or to a carbonyl oxygen of the next molecule (i.e. the N11-H11···O2 and the N9-H9···O4 contacts). In this way, the pairs of molecules are linked into chains along b, as shown in Figure 2.
Experimental 0.0163 g (1.0 mmol) of 4-acetoaminebenzaldehyde and 0.0911 ml (1.0 mmol) of aniline were dissolved in 10.0 ml 95% ethanol separately. Both solutions were mixed in 100 ml round bottom flask. The mixture was refluxed for two hours at 423 K. It was then recrystallized by using a mixture of acetonitrile, methanol and water in the ratio 1: 3: 4 respectively.

Refinement
H atoms bonded to C were included in calculated positions using the riding method, with aromatic and methyl C-H distances of 0.98 and 0.95 Å, respectively and U eq values 1.2 and 1.5 times those of the parent atoms; the torsion angles of the methyl H atoms were optimized to give the best fit to the electron density. H atoms bonded to N and O were found by difference Fourier methods and refined isotropically with restraints on the bond lengths and with the U eq value constrained to be 1.2 or 1.5 times that of the parent atom. The N-H distances vary from 0.86 (2) to 0.88 (2) Å and the O-H distances range from 0.83 (2) to 0.98 (2) Å. Fig. 1. Plot of one molecule of (I) with ellipsoids drawn at the 50% probability level.

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.