5-Chloro-3-ethylsulfinyl-2-(3-fluorophenyl)-1-benzofuran

The asymmetric unit of the title compound, C16H12ClFO2S, contains two independent molecules in which the benzofuran ring systems are essentially planar, with r.m.s. deviations of 0.007 (1) and 0.013 (1) Å. In the crystal, molecules are linked by weak C—H⋯O hydrogen bonds into chains extending along the b axis. These chains are further packed into stacks along the c -axis by S⋯O contacts [3.1898 (11) and 3.1361 (11) Å] involving the sulfinyl groups. In both 3-fluorophenyl rings, the F atom is disordered over two positions, with site-occupancy factors of 0.921 (2) and 0.079 (2).

The asymmetric unit of the title compound, C 16 H 12 ClFO 2 S, contains two independent molecules in which the benzofuran ring systems are essentially planar, with r.m.s. deviations of 0.007 (1) and 0.013 (1) Å . In the crystal, molecules are linked by weak C-HÁ Á ÁO hydrogen bonds into chains extending along the b axis. These chains are further packed into stacks along the c -axis by SÁ Á ÁO contacts [3.1898 (11) and 3.1361 (11) Å ] involving the sulfinyl groups. In both 3fluorophenyl rings, the F atom is disordered over two positions, with site-occupancy factors of 0.921 (2) and 0.079 (2).
In the title molecule ( Fig. 1), the benzofuran unit is essentially planar, with a mean deviation of 0.007 (1) and 0.013 (1) Å, for A and B molecule, respectively, from the least-squares plane defined by the nine constituent atoms. In the 3-fluorophenyl rings of both molecules, the F atoms are disordered over two positions with site-occupancy factors, from refinement of 0.921 (2) (part A) and 0.079 (2) (part B). The dihedral angles between the 3-fluorophenyl ring and the mean plane of the benzofuran ring system are 15.35 (8)° in the molecule A and 5.62 (9)° in the molecule B, respectively. In the crystal packing (Fig. 2), molecules are connected by weak C-H···O hydrogen bonds (Table 1) into chains extending along the b-axis direction.

Experimental
3-Chloroperoxybenzoic acid (77%, 269 mg, 1.2 mmol) was added in small portions to a stirred solution of 5-chloro-3ethylsulfanyl-2-(3-fluorophenyl)-1-benzofuran (337 mg, 1.1 mmol) in dichloromethane (40 mL) at 273 K. After being stirred at room temperature for 5h, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated at reduced pressure. The residue was purified by column chromatography (hexane-ethyl acetate, 2:1 v/v) to afford the title compound as a colorless solid [yield 67%, m.p. 390-391 K; R f = 0.59 (hexane-ethyl acetate, 24:1 v/v)]. Single crystals suitable for X-ray diffraction were prepared by slow evaporation of a solution of the title compound in acetone at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 Å for aryl, 0.99 Å for methylene and 0.98Å for methyl H atoms, respectively. U iso (H) = 1.2U eq (C) for aryl and methylene, and 1.5U eq (C) for methyl H atoms. The positions of methyl hydrogens were optimized rotationally. The F1 and F2 atoms of the 3-fluorophenyl rings are disordered over two positions with site occupancy factors, from refinement of 0.921 (2) (part A) and 0.079 (2) (part B). For the proper treatment of H-atoms, carbon atoms C11 and C13 (molecule A), and C27 and C29 (molecule B) were divided in two parts with equalized coordinates and thermal parameters. The distance of equivalent C-F pairs were restrained to 1.330 (5) Å using command DFIX, and displacement ellipsoids of F1 and F2 sets were restrained to 0.01 using command ISOR. program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figure 1
The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius. The F atom of the 3-fluorophenyl ring is disordered over two positions with site occupancy factors, from refinement of 0.921 (2) (part A) and 0.079 (2) (part B).   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.35 e Å −3 Δρ min = −0.38 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 > 2sigma(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.