1,3-Bis(phenylsufanylmethyl)benzene

The complete molecule of the title compound, C20H18S2, is generated by crystallographic mirror symmetry, with two C atoms lying on the mirror plane. All of the independent atoms are contained within two planes defined by the thiophenyl rings (C6S) and the central phenyl ring with the methylene bridge; the r.m.s deviations of these planes are 0.012 and 0.025 Å, respectively. The two planes are almost perpendicular to one another at a dihedral angle of 80.24 (10)°. Intermolecular C—H—π interactions are present in the crystal structure.

The complete molecule of the title compound, C 20 H 18 S 2 , is generated by crystallographic mirror symmetry, with two C atoms lying on the mirror plane. All of the independent atoms are contained within two planes defined by the thiophenyl rings (C 6 S) and the central phenyl ring with the methylene bridge; the r.m.s deviations of these planes are 0.012 and 0.025 Å , respectively. The two planes are almost perpendicular to one another at a dihedral angle of 80.24 (10) . Intermolecular C-H-interactions are present in the crystal structure.

Comment
The title compound, 1,3-bis(phenylthiomethyl)benzene, belongs to a class of transition metal ligands known as SCS-pincer ligands because of their tendency to act as tridentate chelators through one carbon and two sulfur atoms. The plane containing the thiophenyl ring is rotated almost perpendicular to the plane of the central phenyl ring, at an angle of 80.24 (10)°. This is comparable to the para-fluoro (Cervantes et al., 2006) andortho-ethylester (Sillanpää et al., 1994) derivatives, whose interplanar angles measure 78.13 (10) and 87.66 (10)° respectively. Surprisingly, in the only other structurally characterized derivative, the perfluorinated 1,3-bis(pentafluorophenylthiomethyl)benzene (Arroyo et al., 2003), the rings are nearly co-planar with angles of 8.93 (10) and 10.85 (9)° between the central phenyl and the two independent flanking perfluoro rings. In both the title compound and the para-fluoro derivative, the flanking aryl rings are oriented on the same face of the central ring.
Although the structure of the title compound has not been previously determined, several of its metal complexes are known. Two types of coordination were observered in structurally characterized metal complexes. In the presence of silver perchlorate (Bu et al., 2002) or silver nitrate (Romero et al., 1996), the title compound acts as a bridging ligand through sulfur. In these two complexes, the flanking aryls remain on the same face of the central ring. With Pd (Loeb & Wisner, 1998), Pt (Kruithof et al., 2008) and Te (Bergholdt et al., 1998;Kobayashi et al., 2000) the much more common trihapto-SCS "pincer"-type coordination is observed and the thiophenyl rings rotate to opposite faces of the central phenyl. In all seven examples, the mirror plane present within the free ligand has been broken. The nearly perpendicular orientation of the planes of flanking aryls and the central phenyl (80.24 (10)°) is maintained in each of the Te (Bergholdt et al., 1998;Kobayashi et al., 2000) and Pt (Kruithof et al., 2008) complexes, which have interplanar angles ranging from 77.8 (3) to 89.7 (3)°.
Experimental 1,3-Bis((phenylthio)methyl)benzene was synthesized according to the literature method (Romero, et al. 1996). To grow crystals, a saturated solution of 1,3-bis((phenylthio)methyl)benzene was prepared in hot pentane. An aliquot of this saturated solution was transferred to a 20 ml vial, which was then tightly capped. The vial was placed in a bath of hot water and allowed to slowly cool to room temperature. Colorless, needle-like crystals of up to 10 mm in length formed over approximately 30 minutes. The solvent was then decanted and the crystals allowed to air dry. Several needles of ca. 1 mm in length were placed in a melting point capillary with an internal diameter 0.5 mm and the melting point was determined to be 84 -86 °C.
supplementary materials sup-2 Refinement Hydrogen atoms were included at geometrically idealized positions with C-H distances of 0.94 Å for aryl H atoms and 0.98 Å for methylene H atoms. The hydrogen atoms were treated as riding on their respective heavy atoms. The isotropic thermal parameters of the hydrogen atoms were fixed at 1.2 U eq of the parent atom. Fig. 1. View of the title compound showing full numbering scheme. The displacement ellipsoids are shown at the 50% probability level.

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 > σ(F 2 ) is used only for calculating Rfactors(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.