N-[(1E)-5-(3-Chlorophenyl)-3-methylcyclohex-2-en-1-ylidene]hydroxylamine

The whole of the title molecule, C13H14ClNO, is disordered over two sets of sites with a refined occupancy ratio of 0.560 (6):0.440 (6). The oxime group having a C=N double bond adopts an E conformation. The dihedral angles between the rings (all atoms) are 89.5 (5) (major componenent) and 88.0 (6)° (minor component).


Comment
Oximes are a classical type of chelating ligands which are widely used in coordination and analytical chemistry (Kukushkin et al., 1996;Chaudhuri, 2003).
The bond lengths and bond angles of the title compound are comparable with those observed in other chlorophenyl oxime derivative. (Ravichandran et al., 2010). The whole molecule of the title compound is disordered over two positions ( Fig. 1 and 2) with a refined occupancy ratio of 0.560:0.440 (6) angle 88.0 (6) °. In the crystal unit, the oxime groups C2=N1 and C2′=N1′ double bond exists in E configuration, which is confirmed by the torsion angle of -177.7 (2) and 177.0 (2)° of C3-C2-N1-O1 and C3′-C2′-N1′-O1′ moeity respectively. Phenyl ring is completely planar, while cyclohexene ring is far from being planar with maximum deviations from the mean plane being 0.195 (2) and 0.241 (7) Å for the C1 and C6′ atoms respectively.

Experimental
To a stirred suspension of benzo[c]furan (2.38 g, 7.437 mmol) in dry THF (20 ml), lead tetraacetate (3.2 g, 7.437 mmol) was added and refluxed at 50°C for half an hour. The reaction mixture was then poured into water (200 ml) and extracted with ethyl acetate (2 x 20 ml), washed with brine solution and dried (Na 2 SO 4 ). The removal of solvent in vacuo followed by crystallization from methanol afforded the title compound as a colorless solid. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a solution of the title compound in methanol at room temperature.

Refinement
The whole molecule was disordered over two sites (C1-C13/Cl/N1/O1 and C1′-C13′/Cl′/N1′/O1′) with refined occupancy ratio 0.560:0.440 (6). Displacement ellipsoid and bond distance similarity restraints were employed to control the geometry of both disorder components. The residual factors are R1 = 0.0803 and wR2 = 0.2417 are rather high. The data were collected with the body centred tetragonal cell as the Bravais cell and processed in the Laue class 4/m. The multiscan absorption correction was done assuming in the crystal to be medium absorber. The residual factors are high, probably due to the restraints needed to account for completely disordered molecule. The actual disorder probably could be several fold with each having slightly different orientation. The idealized two fold disorder may not be accounting for the full disorder. All H atoms were fixed geometrically and allowed to ride on their parent C atoms, with C-H distances fixed in the range 0.93-0.97 Å with U iso (H) = 1.2U eq (C) for other H atoms.

Figure 1
The molecular structure of the major component of title compound with 30% probability displacement ellipsoids.

Figure 2
Stick plot of both major and minor components of the title compound with atom labels for non-H atoms.  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 R-factors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (