2,5-Bis(4-fluorophenyl)-2-methylsulfanyl-1-benzofuran

The crystal studied of the title compound, C21H14F2OS, was an inversion twin with a 0.67 (8):0.33 (8) domain ratio. The 4-fluorophenyl ring in the 2-position makes a dihedral angle of 25.14 (6)° with the mean plane of the benzofuran fragment, and the dihedral angle between 4-fluorophenyl ring in the 5-position and the mean plane of the benzofuran fragment is 28.50 (7)°. In the crystal, molecules are linked through weak intermolecular C—H⋯F and C—H⋯π interactions.

The crystal studied of the title compound, C 21 H 14 F 2 OS, was an inversion twin with a 0.67 (8):0.33 (8) domain ratio. The 4fluorophenyl ring in the 2-position makes a dihedral angle of 25.14 (6) with the mean plane of the benzofuran fragment, and the dihedral angle between 4-fluorophenyl ring in the 5position and the mean plane of the benzofuran fragment is 28.50 (7) . In the crystal, molecules are linked through weak intermolecular C-HÁ Á ÁF and C-HÁ Á Á interactions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SJ5110).

Comment
Many compounds having a benzofuran ring system exhibit interesting pharmacological properties such as antifungal, antitumor and antiviral, and antimicrobial activities (Aslam et al., 2006, Galal et al., 2009, Khan et al., 2005. These compounds occur in a wide range of natural products (Akgul & Anil, 2003;Soekamto et al., 2003). As a part of our ongoing study of substituent effects on the solid state structures of 3-alkylsulfanyl-2-(4-fluorophenyl)-5-phenyl-1-benzofuran analogues (Choi et al., 2009(Choi et al., , 2010, we report herein on the crystal structure of the title compound.
The title compound crystallizes as the non-centrosymmetric space group P2 1 in spite of having no asymmetric C atoms.

Experimental
Zinc chloride (245 mg, 1.8 mmol) was added to a stirred solution of 4-fluoro-4'-hydroxybiphenyl (339 mg, 1,8 mmol) and 2-chloro-4'-fluoro-2-methylsulfanylacetophenone (395 mg, 1.8 mmol) in dichloromethane (30 mL) at room temperature, and stirring was continued at the same temperature for 40 min. The reaction was quenched by the addition of water and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated at reduced pressure. The residue was purified by column chromatography (carbon tetrachloride) to afford the title compound as a colorless solid [yield 65%, m.p. 438-439 K; Rf = 0.69 (carbon tetrachloride)]. 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
The reported Flack parameter was obtained by TWIN/BASF procedure in SHELXL (Sheldrick, 2008). All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 Å for aryl and 0.98 Å for methyl H atoms.
U iso (H) =1.2U eq (C) for aryl and 1.5U eq (C) for methyl H atoms.  Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as a small spheres of arbitrary radius. 2,5-Bis(4-fluorophenyl)-2-methylsulfanyl-1-benzofuran

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.