X-ray crystal and computational structural study of (E)-2-[(2-chlorophenyl)iminomethyl]-4-methoxyphenol

In the molecule of the title compound, C14H12ClNO, the two aromatic rings are oriented at a dihedral angle of 12.28 (7)°. An intramolecular O—H⋯N hydrogen bond results in the formation of a nearly planar six-membered ring, which is oriented with respect to the aromatic rings at dihedral angles of 0.18 (5) and 12.10 (6)°. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules into chains along the c axis. There is a C—H⋯π contact between the methyl group and the chlorophenyl ring and a π–π contact between the two benzene rings [centroid–centroid distance = 3.866 (1) Å].

In the molecule of the title compound, C 14 H 12 ClNO, the two aromatic rings are oriented at a dihedral angle of 12.28 (7) . An intramolecular O-HÁ Á ÁN hydrogen bond results in the formation of a nearly planar six-membered ring, which is oriented with respect to the aromatic rings at dihedral angles of 0.18 (5) and 12.10 (6) . In the crystal structure, weak intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into chains along the c axis. There is a C-HÁ Á Á contact between the methyl group and the chlorophenyl ring and acontact between the two benzene rings [centroid-centroid distance = 3.866 (1) Å ].   Table 1 Hydrogen-bond geometry (Å , ).

Comment
The present work is part of a structural study of Schiff bases Özek et al., 2007;Odabaşoğlu, Büyükgüngör et al., 2007;Odabaşoğlu, Arslan et al., 2007). We report herein the crystal structure of the title compound, (I).
In the crystal structure, weak intermolecular C-H···O hydrogen bonds (Table 1) results in the formation of C(5) chains along the c axis ( Fig. 2), in which they may be effective in the stabilization of the structure. A C-H···π contact (Table   1) between the methyl group and ring B and a π-π contact ( Fig. 3) between the symmetry related A rings Cg1···Cg1 i [symmetry code: (i) 1 -x, 1 -y, -z, where Cg1 is the centroid of ring A] further stabilize the structure, with centroid-centroid distance of 3.866 (1) Å.
Ab-initio Hartree-Fock (HF), density-functional theory (DFT) and semi-empirical (AM1 and PM3) calculations and full-geometry optimizations were performed by means of GAUSSIAN 03 W package (Frisch et al., 2004). The selected bond lengths and angles together with the torsion angles are compared with the obtained ones from semi-empirical, ab-initio HF and DFT/B3LYP methods (Table 2). We observe an acceptable general agreement between them. Although the DFT molecular orbital theory was considered as the most accurate method for geometry optimization for free and complex ligands (Friesner, 2005;Liu et al., 2004), the HF method led to better results in regard to the bond lengths and angles.

Experimental
The title compound was prepared by refluxing a mixture of a solution containing 5-methoxysalicylaldehyde (0.5 g 3.3 mmol) in ethanol (20 ml) and a solution containing 2-chloroaniline (0.420 g 3.3 mmol) in ethanol (20 ml). The reaction mixture was stirred for 1 h, under reflux. The crystals suitable for X-ray analysis were obtained from ethanol by slow evaporation (yield; 75%; m.p. 393-394 K).

Refinement
H1 atom (for OH) was located in difference syntheses and refined isotropically [O-H = 0.80 (2) Å and U iso (H) = 0.082 (6) Å 2 ]. The remaining H atoms were positioned geometrically, with C-H = 0.93 and 0.96 Å for aromatic and methyl H, respectively, and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 20% probability level. Hydrogen bond is shown as dashed line.