1,2-Bis(4-ethynylphenyl)disulfane

In the title compound, C16H10S2, the S atoms are almost coplanar with the benzene rings to which they are bonded [deviations of 0.092 (1) and 0.022 (1) Å from their respective ring planes]. The benzene rings enclose a dihedral angle of 79.17 (3)°. An intramolecular C—H⋯S hydrogen bond results in the formation of a five-membered ring. In the crystal structure, molecules are stacked parallel to the a axis direction. π–π interactions between benzene rings are present, with a face-to-face stacking distance of 3.622 (10) Å.


Comment
The title compound, (I), is a kind of aromatic acetylide organic intermediate which can be used for many fields such as molecular electronic materials, organometallic chemistry etc. (Yonezawa et al., 2008). We herein report its crystal structure.
In the molecule of (I), (Fig.1), the bond lengths and angles are within normal ranges (Allen et al., 1987). S atoms are situated in the same plane as the benzene rings they are bonded to. Rings A (C3-C8) and B (C11-C16) are, of course, planar and they enclose a dihedral angle of 79.17 (3) °. An intramolecular C-H···S hydrogen bond (Table 1) results in the formation of a five-membered ring C (S1/S2/C14/C13/H13A). The distance between atoms S2 and H5A is 2.91 Å, which is significantly longer than the hydrogen bond between atoms S1 and H13A.
As can be seen from the packing diagram, (Fig. 2), the molecules are stacked along the a axis. There are also the π-π interactions of benzene rings with a face-to-face stacking distance of 3.622 Å.

Experimental
The title compound, (I) was prepared by a literature method (Yonezawa et al., 2008). Crystals suitable for X-ray analysis were obtained by dissolving (I) (0.5 g) in hexane (20 ml) and evaporating the solvent slowly at room temperature for about 7 d.

Refinement
H atoms were positioned geometrically, with C-H = 0.93 Å for aromatic H and 0.95 Å for acetylide H. In the refinement all hydrogens were constrained to ride on their parent atoms, with U iso (H) = xU eq (C), with x = 1.2 for aromatic H, and x = 1.5 for other H.

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.