Crystal structures of three N-acylhydrazone isomers

The crystal structures of three isomers of (E)-4-chloro-N-{2-[2-(chlorobenzylidene)hydrazinyl]-2-oxoethyl}benzenesulfonamide, namely, (E)-4-chloro-N-{2-[2-(2-chlorobenzylidene)hydrazinyl]-2-oxoethyl}benzenesulfonamide (I), (E)-4-chloro-N-{2-[2-(3-chlorobenzylidene)hydrazinyl]-2-oxoethyl}benzenesulfonamide (II) and (E)-4-chloro-N-{2-[2-(4-chlorobenzylidene)hydrazinyl]-2-oxoethyl}benzenesulfonamide (III), with the general formula C15H13Cl2N3O3S are described, with the chloro group in ortho, meta and para positions in the benzylidene benzene ring. All the three isomeric compounds crystallize in the centrosymmetric triclinic P space group with one molecule each in the asymmetric unit and two molecules in the unit cell. In all the three crystals, the molecules form inversion dimers with (8) ring motifs, which are further augmented by C—H⋯O interactions.

, with the general formula C 15 H 13 Cl 2 -N 3 O 3 S are described, with the chloro group in ortho, meta and para positions in the benzylidene benzene ring. All the three isomeric compounds crystallize in the centrosymmetric triclinic P1 space group with one molecule each in the asymmetric unit and two molecules in the unit cell. The dihedral angles between the two phenyl rings are 11.09 (14), 53.79 (18) and 72.37 (11) in (I), (II) and (III), respectively. The central part of the molecule (-C-N-N C-) is almost linear with C-N-N-C torsion angles of 179.1 (2), À169.5 (3) and 178.5 (2) for (I), (II) and (III), respectively. In all the three crystals, the molecules form inversion dimers with R 2 2 (8) ring motifs, which are further augmented by C-HÁ Á ÁO interactions.

Chemical context
The properties of molecules in solution and the solid state are strongly influenced by weak non-covalent interactions. Weak molecular interactions are investigated routinely in the areas of molecular recognition (Brouwer et al., 1999), self-assembly (Seth et al., 2011), supramolecular chemistry and general hostguest interactions (Kim et al., 2000;Sharma et al., 2009). Analysis of intermolecular interactions and estimation of their energies provide greater insights into molecular conformations (Cao et al., 2020;Jablonski, 2020). The nature and site of substituents influence the extent of polarization of electron distribution in covalent compounds. In our previous work (Purandara et al., 2017a,b), the presence of the electronwithdrawing nitro group on the benzene ring was found to decrease the electronic density, rendering aromatic C-H protons acidic, whereas a methyl substituent did not activate aromatic protons for participation in intermolecular C-HÁ Á ÁO interactions. In a continuation of these efforts to study the effect of substituents on weak molecular interactions, we report herein the synthesis, characterization and crystal structures of three isomeric molecules. ISSN 2056-9890

Supramolecular features
In the crystal of (I), the carbonyl oxygen (O3) shows bifurcated hydrogen bonding. In one part, the molecules are linked by a pair of N2-H2NÁ Á ÁO3 hydrogen bonds involving the amide NH atom, forming inversion dimers with an R 2 2 (8) ring motif. In the other part, the molecules are linked by a pair of N1-H1NÁ Á ÁO3 hydrogen bonds with the sulfonamide NH atom of another molecule, forming rings with an R 2 2 (10) graphset motif, leading to a layered structure with the mean planes of the layers inclined to the ab plane by 16.1 (5) ( Table 1, Fig. 4). In the crystal of (II), the molecules are linked by two pairs of N-HÁ Á ÁO hydrogen bonds (N1-H1NÁ Á ÁO2 and Molecular structure of (I), showing the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Figure 2
The molecular structure of (II), showing the atom labelling and displacement ellipsoids drawn at the 50% probability level. The intramolecular hydrogen bond is depicted by a dashed line.

Database survey
Comparison of structures (I)-(III) with those of related Nacylhydrazone derivatives (Purandara et al., 2017(Purandara et al., , 2018 shows that the site of substitution of an electron-withdrawing group on the aromatic ring plays a major role in stabilizing the crystal packing by linking the molecules through various weak interactions. A partial packing diagram for (II) with N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds depicted, respectively, by light-blue and black dashed lines. The C-HÁ Á Á(ring) interactions are depicted by violet dashed lines. Table 2 Hydrogen-bond geometry (Å , ) for (II).

Figure 6
A portion of one chain in (III) viewed along the a-axis direction with hydrogen bonds depicted as in Fig. 5.

Figure 4
A view of a portion of one chain of inversion dimers in (I) connected by N-HÁ Á ÁO hydrogen bonds (dashed lines) and extending along the a-axis direction.

Synthesis and crystallization
General procedure for the synthesis of N-(4-chlorobenzenesulfonyl) glycine hydrazone derivatives (I)-(III) A mixture of N-(4-chlorobenzenesulfonyl) glycinyl hydrazide (0.01 mol) and the appropriate chlorobenzaldehyde (0.01 mol) in anhydrous methanol (30 mL) and two drops of glacial acetic acid was refluxed for 8 h. After cooling, the precipitate was collected by vacuum filtration, washed with cold methanol and dried. It was recrystallized to constant melting point from methanol. The purity of the compound was checked by TLC and characterized by its IR and NMR spectra. Single crystals suitable for the X-ray diffraction study were grown from DMF solution by slow evaporation of the solvent.

Special details
Experimental. CrysAlis RED (Oxford Diffraction, 2009) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. 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.

Special details
Experimental. CrysAlis RED, Oxford Diffraction Ltd., 2009 Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. 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. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.