A monoclinic polymorph of N-(3-chlorophenyl)benzamide

The title compound, C13H10ClNO, (I), is a polymorph of the structure, (II), first reported by Gowda et al. [Acta Cryst. (2008), E64, o462]. In the original report, the compound crystallized in the orthorhombic space group Pbca (Z = 8), whereas the structure reported here is monoclinic P21/c (Z = 4). The principal difference between the two forms lies in the relative orientations of the phenyl and benzene rings [dihedral angle = 8.90 (13)° for (I) and 61.0 (1)° for (II)]. The inclination of the amide –CONH– units to the benzoyl ring is more similar [15.8 (7)° for (I) and 18.2 (2)° for (II)]. In both forms, the N—H bonds are anti to the 3-chloro substituents of the aniline rings. In the crystal, intermolecular N—H⋯O hydrogen bonds form C(4) chains along c. These chains are bolstered by weak C—H⋯O interactions that generate R 2 1(6) and R 2 1(7) ring motifs.

The title compound, C 13 H 10 ClNO, (I), is a polymorph of the structure, (II), first reported by Gowda et al. [Acta Cryst. (2008), E64, o462]. In the original report, the compound crystallized in the orthorhombic space group Pbca (Z = 8), whereas the structure reported here is monoclinic P21/c (Z = 4). The principal difference between the two forms lies in the relative orientations of the phenyl and benzene rings [dihedral angle = 8.90 (13) for (I) and 61.0 (1) for (II)]. The inclination of the amide -CONH-units to the benzoyl ring is more similar [15.8 (7) for (I) and 18.2 (2) for (II)]. In both forms, the N-H bonds are anti to the 3-chloro substituents of the aniline rings. In the crystal, intermolecular N-HÁ Á ÁO hydrogen bonds form C(4) chains along c. These chains are bolstered by weak C-HÁ Á ÁO interactions that generate R 2 1 (6) and R 2 1 (7) ring motifs.

A monoclinic polymorph of N-(3-chlorophenyl)benzamide
A. Saeed, M. Arshad and J. Simpson Comment N-substituted benzamides have numerous pharmaceutical and synthetic applications (Saeed et al., 2010). The title compound, (I), is a monoclinic polymorph of the structure of this benzamide derivative which crystallizes in the space group P21/c. An alternative structure, (II), in the orthorhombic space group Pbca was reported previously by Gowda, Tokarčík et al., (2008).

Experimental
Freshly distilled benzoyl chloride (1 mmol) in CHCl 3 was treated with 3-chloroaniline (3.5 mmol) under a nitrogen atmosphere at reflux for 2.5 h. Upon cooling, the reaction mixture was diluted with CHCl 3 and washed consecutively with 1 M aq HCl and saturated aq NaHCO 3 . The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. Crystallization of the residue from ethanol afforded the title compound (83%) as colourless crystals: Anal. calcd.

Refinement
The H atom bound to N1 was located in a difference map and refined isotropically. All other H-atoms were positioned geometrically and refined using a riding model with d(C-H) = 0.95 Å, U iso = 1.2U eq (C).
supplementary materials sup-2 Figures   Fig. 1. The structure of (I) with displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level.