5,7-Bis(1-benzothiophen-2-yl)-2,3-dihydrothieno[3,4-b][1,4]dioxine

In the title compound, C22H14O2S3, the dioxane ring is disordered over two sites [site occupancies = 0.623 (3) and 0.377 (3)]; both components adopt half-chair conformations. The two benzothiophene ring systems are asymmetrically twisted away from the attached thiophene ring [dihedral angles = 20.57 (3) and 6.70 (3)°] and are oriented at an angle of 26.83 (3)°. No significant hydrogen bonding or π–π interactions are observed in the crystal structure.

In the title compound, C 22 H 14 O 2 S 3 , the dioxane ring is disordered over two sites [site occupancies = 0.623 (3) and 0.377 (3)]; both components adopt half-chair conformations. The two benzothiophene ring systems are asymmetrically twisted away from the attached thiophene ring [dihedral angles = 20.57 (3) and 6.70 (3) ] and are oriented at an angle of 26.83 (3) . No significant hydrogen bonding orinteractions are observed in the crystal structure.

Experimental
The C1-C8/S3 and C15-C22/S2 benzothiophene ring systems are essentially planar and are oriented at angles of 20.57 (3)° and 6.70 (3)°, respectively, with respect to the thiophene ring. The dihedral angle between the two benzothiophene ring systems is 26.83 (3)°. Both the major and minor conformers of the disordered dioxane ring adopt half-chair conformations. The crystal packing is stabilized by van der Waals forces.

Experimental
The title compound was prepared according to the procedure reported by Amaladass et al. (2007). Single crystals suitable for X-ray analysis were obtained by slow evaporation method.

Refinement
The methylene C atoms of the dioxane ring are disordered over two positions (C11A/C11B and C12A/C12B) with refined occupancies of 0.623 (3) and 0.377 (3). The corresponding bond distances involving the disordered atoms were restrained to be equal, and also the same U ij parameters were used for atoms C11A and C11B, and C12A and C12B. H atoms were positioned geometrically (C-H = 0.93 Å or 0.97 Å) and were treated as riding on their parent atoms, with U iso (H) = 1.2U eq (C). Fig. 1

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 R-supplementary materials sup-3 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.