Crystal structure of 1,1′-[selanediylbis(4,1-phenylene)]bis(2-chloroethan-1-one)

In the title molecule, C16H12Cl2O2Se, the C—Se—C angle is 100.05 (14)°, with the dihedral angle between the planes of the benzene rings being 69.92 (17)°. The average endocyclic angles (Se—Car—Car; ar = aromatic) facing the Se atom are 120.0 (3) and 119.4 (3)°. The Se atom is essentially coplanar with the benzene rings, with Se—Car—Car—Car torsion angles of −179.2 (3) and −179.7 (3)°. In the crystal, molecules are linked via C—H⋯O hydrogen bonds forming chains propagating along the a-axis direction. The chains are linked via C—H⋯π interactions, forming a three-dimensional network.


Related literature
For a review of organoselenium chemistry, see: Procter (2001). For there uses as reagents and intermediates in organic synthesis, see: Zade et al. (2005). For their use as intermediates in the synthesis of pharmaceuticals, see: Woods et al. (1993), and fine chemicals and polymers, see: Hellberg et al. (1997). For their biological properties, see: Zhu & Jiang (2008); Anderson et al. (1996); Abdel-Hafez (2008). For details of how selenium compounds play important roles in protecting the heart, preventing cancer and cardiovascular diseases, see: Yang et al. (2005). For details of how selenium functions as an antioxidant in conjunction with vitamin E, see: Ellis et al. (1984). For the synthesis, see: Mechehoud et al. (2010). For related structures, see: Zuo (2013); Bouraoui et al. (2011 Table 1 Hydrogen-bond geometry (Å , ).
Cg1 and Cg2 are the centroids of benzene rings C1-C6 and C7-C12, respectively. During the last few years, organoselenium chemistry (Procter, 2001) has been the subject of constant scientific interest and organoselenium compounds have been used intensively as important reagents and intermediates in organic synthesis (Zade et al., 2005). Moreover, organoselenium compounds are of considerable interest as anti-cancer (Zhu & Jiang, 2008), anti-oxydant (Anderson et al., 1996), anti-inflammatory, and antiallergic agents (Abdel-Hafez, 2008) and they are key intermediates for the synthesis of pharmaceuticals (Woods et al., 1993), fine chemicals and polymers (Hellberg et al., 1997). Selenium compounds have been found to play important roles in protecting the heart, preventing cancer and cardiovascular diseases (Yang et al., 2005). Because selenium functions as an antioxidant it works in conjunction with vitamin E (Ellis et al., 1984).
In the crystal of the title compound, molecules are linked by C-H···O hydrogen bonds forming chains along the a axis direction (Table 1 and Fig. 2). The chains are linked by C-H···π interactions (Table 1) forming a three-dimensional structure.

S2. Synthesis and crystallization
The title compound was prepared according to a method proposed by (Mechehoud et al., 2010). Methylene chloride acyl chloride, ClCH 2 COCl, (36.5 mmol) and anhydrous aluminium chloride 5 g (37.5 mmol, 3 eq) were taken in dry CH 2 Cl 2 (100 ml). The reaction mixture was cooled to 273-278 K, protected from atmospheric moisture, and stirred continuously for 15 min. A solution of diphenyl selenide (1) 3 g (1.87 mmol) in CH 2 Cl 2 was added drop wise over a period of 5 min.
The reaction mixture was allowed to reach room temperature gradually and then stirred at this temperature overnight. The solution was then washed with ice water-HCl (80 ml) and extracted with CH 2 Cl 2 . The organic layer was separated and dried (Na 2 SO 4 ). Removal of the solvent under reduced pressure afforded the crude product which was recrystallized from ether-petrol to yield 4.2 g of the title compound. Yellow single crystals suitable for X-ray diffraction were obtained by recrystallization from CH 2 Cl 2 .

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2 The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Crystal packing of the title compound, viewed along the b axis. The hydrogen bonds are shown as dashed lines (see Table   1).