N-(3-Chlorophenyl)-N′-(3-methylphenyl)succinamide

The asymmetric unit of the title compound, C17H17ClN2O2, contains one half-molecule with a center of inversion at the mid-point of the central C—C bond. The amide N—H group is anti to the meta-chloro/methyl groups in the adjacent benzene rings. The dihedral angle between the benzene ring and the NH—C(O)—CH2 segment is 43.5 (1)°. In the crystal, intermolecular N—H⋯O hydrogen bonds link the molecules into chains along the a axis. The methyl group and the Cl atom occupy the same position and were treated in a disorder model with site-occupation factors of 0.5 each.

The asymmetric unit of the title compound, C 17 H 17 ClN 2 O 2 , contains one half-molecule with a center of inversion at the mid-point of the central C-C bond. The amide N-H group is anti to the meta-chloro/methyl groups in the adjacent benzene rings. The dihedral angle between the benzene ring and the NH-C(O)-CH 2 segment is 43.5 (1) . In the crystal, intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into chains along the a axis. The methyl group and the Cl atom occupy the same position and were treated in a disorder model with site-occupation factors of 0.5 each.
BSS thanks the University Grants Commission, Government of India, New Delhi, for the award of a research fellowship under its faculty improvement program.
The conformations of the amide O atoms are anti to the H atoms attached to the adjacent C atoms. Further, the conformations of the N-H bonds in the amide fragments are anti to the meta-chloro/methyl groups in the adjacent benzene rings, similar to the anti conformations observed with respect to the meta-chloro groups in (III) and meta-methyl groups in (IV).
The packing of the molecules in the crystal is accomplished by N-H···O hydrogen bonds ( Table 1) that lead is shown in Fig. 2.

Experimental
Succinic anhydride (0.01 mol) in toluene (25 ml) was treated dropwise with 3-chloroaniline (0.01 mol) also in toluene (20 ml) with constant stirring. The resulting mixture was stirred for one hour and set aside for an additional hour at room temperature for completion of the reaction. The mixture was then treated with dilute hydrochloric acid to remove unreacted 3-chloroaniline. The resultant solid N-(3-chlorophenyl)-succinamic acid was filtered under suction and washed thoroughly with water to remove the unreacted succinic anhydride and succinic acid. The compound was recrystallized to a constant melting point from ethanol. The purity of the compound was checked by elemental analysis and characterized by its infrared and NMR spectra. water, dilute sodium hydroxide solution and finally with water. It was recrystallized to a constant melting point from a mixture of acetone and toluene (3:1 v/v). The compound was characterized by its infrared and NMR spectra.
Prism-like colorless single crystals used in X-ray diffraction studies were grown in a mixture of acetone and toluene (3:1 v/v) at room temperature.

Refinement
The H atoms were positioned with idealized geometry using a riding model with C-H = 0.93 Å for aromatic, C-H = 0.97 Å for methylene and N-H = 0.86 Å for amide H atoms and were refined with isotropic displacement parameters, set to 1.2×U eq of the parent atom. Atoms C9 and Cl1 occupy the same position. The disorder was treated by using a split-atom model.
The corresponding site-occupation factors were fixed to 0.50:0.50. The U ij components of these atoms were restrained to approximate isotropic behavior (Nardelli, 1999), the bond lenghts C3-C9 and C3-Cl1 were restrained.    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 > σ(F 2 ) is used only for calculating Rfactors(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.