2-(4-Fluoro-phen-yl)-3-methyl-sulfanyl-5-phenyl-1-benzofuran.

In the title compound, C(21)H(15)FOS, the 4-fluoro-phenyl ring is rotated out of the benzofuran plane, making a dihedral angle of 24.3 (1)°. The dihedral angle between the phenyl ring and the benzofuran plane is 28.3 (1)°. The crystal structure may be stabilized by two very weak aromatic π-π inter-actions between the furan and the benzene rings of neighbouring benzofuran systems; the centroid-centroid distances are 3.909 (4) and 4.028 (4) Å.

In the title compound, C 21 H 15 FOS, the 4-fluorophenyl ring is rotated out of the benzofuran plane, making a dihedral angle of 24.3 (1) . The dihedral angle between the phenyl ring and the benzofuran plane is 28.3 (1) . The crystal structure may be stabilized by two very weak aromaticinteractions between the furan and the benzene rings of neighbouring benzofuran systems; the centroid-centroid distances are 3.909 (4) and 4.028 (4) Å .
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: VM2006).

Comment
Molecules containing the benzofuran skeleton constitute a major group of naturally-occurring compounds that are of a remarkable interest because of their biological activities (Akgul & Anil, 2003;Soekamto et al., 2003;von Reuss & König, 2004). As a part of our continuing studies of the effect of side chain substituents on the solid state structures of 2,5-diaryl-3-methylsulfanyl-1-benzofuran analogues Choi, Woo et al., 2006), we report the crystal structure of the title compound (Fig. 1).

Experimental
Zinc chloride (273 mg, 2.0 mmol) was added to a stirred solution of 4-phenylphenol (340 mg, 2.0 mmol) and 2-chloro-4'fluoro-2-methylsulfanylacetophenone (437 mg, 2.0 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 separated, dried over magnesium sulfate, filtered and concentrated in vacuum. The residue was purified by column chromatography (carbon tetrachloride) to afford the title compound as a colorless solid [yield 68%, m.p. 431-432 K; R f = 0.71 (carbon tetrachloride)]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in tetrahydrofuran at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93 Å for the aryl H atoms and 0.96 Å for the methyl H atoms, and with U iso (H) = 1.2U eq (C) for the aryl H atoms and 1.5U eq (C) for the methyl H atoms.  2-(4-Fluorophenyl)-3-methylsulfanyl-5-phenyl-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.