5-Iodo-2-phenyl-3-phenylsulfinyl-1-benzofuran

In the title compound, C20H13IO2S, the O atom and the phenyl group of the phenylsulfinyl substituent lie on opposite sides of the plane of the benzofuran fragment; the phenyl ring is almost perpendicular to this plane [83.84 (5)°]. The phenyl ring in the 2-position is rotated out of the benzofuran plane, making a dihedral angle of 40.47 (5)°. The crystal structure is stabilized by non-classical intermolecular C—H⋯O interactions, and by an I⋯O halogen bond of 3.124 (1) Å [C—I⋯O = 165.84 (5)°].

In the title compound, C 20 H 13 IO 2 S, the O atom and the phenyl group of the phenylsulfinyl substituent lie on opposite sides of the plane of the benzofuran fragment; the phenyl ring is almost perpendicular to this plane [83.84 (5) ]. The phenyl ring in the 2-position is rotated out of the benzofuran plane, making a dihedral angle of 40.47 (5) . The crystal structure is stabilized by non-classical intermolecular C-HÁ Á ÁO interactions, and by an IÁ Á ÁO halogen bond of 3.124 (1) Å [C-IÁ Á ÁO = 165.84 (5) ].

Related literature
For the crystal structures of similar 5-iodo-1-benzofuran derivatives, see: Choi et al. (2007a,b). For a review of halogen interactions, see: Politzer et al. (2007). The Cambridge Structural Database (version 5.28;Allen et al., 2002) has 39 compounds with C-IÁ Á ÁO S contact distances less than or equal to 3.3 Å .
The benzofuran unit is essentially planar, with a mean deviation of 0.005 (1) Å from the least-squares plane defined by the nine constituent atoms. The dihedral angle in (I) formed by the planes of the benzofuran and 2-phenyl rings is 40.47 (5)°, and the phenyl ring (C15-C20) with 83.84 (5)° lies toward the benzofuran plane. The crystal packing (Fig. 2) is stabilized by non-classical intermolecular C-H···O interactions; the first between an H atom of the 2-phenyl ring and the oxygen of the S═O unit, with a C10-H10···O2 i , the second between a phenyl H atom of the phenylsulfinyl substituent and the furan O atom, with a C19-H19···O1 ii , the third between a phenyl H atom of the phenylsulfinyl substituent and the oxygen of the S═O unit, with a C20-H20···O2 iii , respectively (Table 1 and Fig. 2; symmetry code as in Fig. 2). The molecular packing ( Fig. 2) is further stabilized by an I···O halogen bond (Politzer et al., 2007) between the iodine atom and the oxygen of neighbouring S═O unit, with an I···O iv (Symmetry code as in Fig. 2). The observed I···O separation of 3.124 (1) Å and the nearly linear C-I···O angle of 165.84 (5)° are typical for such halogen bonds. A search of Cambridge Structural Database (version 5.28; Allen, 2002) revealed 39 compounds with C-I···O═S contact distances equal to or less than 3.3 Å.

Experimental
The 77% 3-chloroperoxybenzoic acid (123 mg, 0.55 mmol) was added in small portions to a stirred solution of 5-iodo-2phenyl-3-phenylsulfanyl-1-benzofuran (214 mg, 0.5 mmol) in dichloromethane (30 mL) at 273 K. After being stirred at room temperature for 3h, the mixture was washed with saturated sodium bicarbonate solution and the organic layer was separated, dried over magnesium sulfate, filtered and concentrated in vacuum. The residue was purified by column chromatography (hexane-ethyl acetate, 2:1 v/v) to afford the title compound as a colorless solid [yield 76%, m.p. 423-424 K; R f = 0.74 (hexane-ethyl acetate, 2:1 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 = 0.93 Å for aromatic H atoms and with Uiso(H) = 1.2Ueq(C) for aromatic H atoms.
supplementary materials sup-2 Figures Fig. 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 a small spheres of arbitrary radius.

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.