N,N′-Bis(2-chlorophenyl)propanediamide

The crystal structure of the title compound, C15H12Cl2N2O2, contains three intramolecular hydrogen bonds; two C—H⋯O and a nonclassical N—H⋯Cl. The structure is further stabilized by intermolecular N—H⋯O hydrogen bonds and C—H⋯π interactions, resulting in a three-dimensional network. The two benzene rings make an interplanar angle of 58.0 (1)°.

The crystal structure of the title compound, C 15 H 12 Cl 2 N 2 O 2 , contains three intramolecular hydrogen bonds; two C-HÁ Á ÁO and a nonclassical N-HÁ Á ÁCl. The structure is further stabilized by intermolecular N-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions, resulting in a three-dimensional network. The two benzene rings make an interplanar angle of 58.0 (1) .
MT and JK thank the Grant Agency of the Slovak Republic (VEGA 1/0817/08) and Structural Funds, Interreg IIIA, for financial support in purchasing the diffractometer. VZR thanks the University Grants Commission, Government of India, New Delhi for the award of a research fellowship.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT5396).
The molecular structure of (I) includes three intermolecular hydrogen bonds ( Table 1); two of them are C-H···O hydrogen bonds, the third is a non-classical N-H···Cl hydrogen bond. The two phenyl rings make an interplanar angle of 58.0 (1)°.
The dihedral angle made by the two amido groups is 65.0 (2)°. The conformation of the ortho-chlorosubstituent is anti to the nearest carbonyl C=O bond, as indicated by the torsion angles, C2-C1-N1-C7 = -156.1 (2)° and C11-C10-N2-C9 = 137.2 (2)° in the first and the second phenyl rings, respectively. The chlorine Cl atom attached to the C1/C6 phenyl ring gives rise to a non conventional N-H···Cl hydrogen bond, with N-Cl distance of 2.9730 (18) Å and angle of 109°. The second chlorine atom, attached to the C10/C15 phenyl ring, makes a short intramolecular contact of 2.960 (2)Å with the nearest amide N atom, forming the N-H···Cl angle of 98°. In the crystal, the molecules are linked by intermolecular N-H···O hydrogen bonds into the chains running along the base vector [0 1 1] parallel to the bc-plane (Fig. 2). The chains are further stabilized by C-H···π interaction between the C3 atom of the C1/C6 ring and the centroid Cg2 of the phenyl ring C10/C15 at the position (-x, y + 1/2, -z + 1/2).

Experimental
Malonic acid (0.3 mol) in dichloromethane (30 ml) was treated with 2-chloroaniline (0.6 mol) in dichloromethane (30 ml), dropwise with stirring. The resulting mixture was stirred for 3 hrs and kept aside for 12 hrs for the completion of reaction and evaporation of the solvent, dichloromethane. The product obtained was added to crushed ice to obtain the precipitate.
The latter was thoroughly washed with water and then with saturated sodium bicarbonate solution and washed again with water. It was then given a wash with 2 N HCl. It was again washed with water, filtered, dried and recrystallized to the constant melting point from ethanol.
Block like colorless single crystals of the title compound used in X-ray diffraction studies were obtained by a slow evaporation of its ehanolic solution at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93 or 0.97 Å and N-H = 0.86 Å. The U iso (H) values were set at 1.2U eq (C, N).