N,N′-Bis(2,5-dichlorophenyl)isophthalamide

The asymmetric unit of the title compound, C20H12Cl4N2O2, contains one half-molecule with a center of symmetry along a C⋯C axis of the central benzene ring. The two C=O groups adopt an anti orientation and the two amide groups are twisted away from the central benzene ring by 27.38 (3) and 27.62 (4)°. The mean planes of the dichloro-substituted benzene rings are twisted by 7.95 (4)° with respect to the benzene ring. The crystal packing is stabilized by weak intermolecular N—H⋯O interactions.

The asymmetric unit of the title compound, C 20 H 12 Cl 4 N 2 O 2 , contains one half-molecule with a center of symmetry along a CÁ Á ÁC axis of the central benzene ring. The two C O groups adopt an anti orientation and the two amide groups are twisted away from the central benzene ring by 27.38 (3) and 27.62 (4) . The mean planes of the dichloro-substituted benzene rings are twisted by 7.95 (4) with respect to the benzene ring. The crystal packing is stabilized by weak intermolecular N-HÁ Á ÁO interactions.
the isophthalamide core function as effective receptors for halide anions in very simple systems (Kavallieratos et al., 1997(Kavallieratos et al., , 1999Light et al. 2006). We report here the crystal structure of the title compound, C 20 H 12 Cl 4 N 2 O 2 , (I), related to these types of receptors.
In the title compound,(I), the asymmetric unit containing one-half of the molecule crystallizes with a center of symmetry along the C2-C5 axis in the benzene ring thereby producing the desired structure ( Fig. 1). In the molecule the two C═O groups adopt an anti orientation and the two amide groups are twisted away from the center benzene ring by 27.38 (3) ° and 27.62 (4) °, respectively. The mean planes of the dichloro substituted benzene rings are twisted by 7.95 (4) ° with that of the benzene ring. Bond lengths are in normal ranges (Allen et al., 1987). Crystal packing is stabilized by weak N-H···O intermolecular interactions (Table 1).
Isophthalogyl chloride (1.01 g, 5 mmol) was added gradually, and the reaction mixture was stirred at room temperature for 2 h and then poured into ice water (100 ml). The product was precipitated as a white powder, which was washed three times with water. Recrystallization from dimethyl sulfoxide solution produced the crystals of the title compound.

Refinement
H atoms were placed in idealized positions and allowed to ride on their respective parent atoms, with C-H = 0.93-0.96 Å, N-H = 0.86Å and U iso (H)= 1.2U eq (C,N) or 1.5U eq (C methyl ). Fig. 1. The molecular structure of the title compound with displacement ellipsoids are drawn at the 30% probability level.