N,N′-Bis[(E)-1-(thiophen-3-yl)ethylidene]ethane-1,2-diamine

The complete molecule of the title compound, C14H16N2S2, is generated by a crystallographic inversion centre. The thiophene residue is close to being coplanar with the imine group [C—C—C—N torsion angle = 6.5 (2)°], and the conformation about the imine C=N bond [1.281 (2) Å] is E. In the crystal, the three-dimensional architecture is consolidated by C—H⋯N, C—H⋯π and S⋯S [3.3932 (7) Å] interactions.

The complete molecule of the title compound, C 14 H 16 N 2 S 2 , is generated by a crystallographic inversion centre. The thiophene residue is close to being coplanar with the imine group [C-C-C-N torsion angle = 6.5 (2) ], and the conformation about the imine C N bond [1.281 (2) Å ] is E. In the crystal, the three-dimensional architecture is consolidated by C-HÁ Á ÁN, C-HÁ Á Á and SÁ Á ÁS [3.3932 (7) Å ] interactions.

Comment
Thiophenes attract attention for their biological activity amongst other properties (Kleemann et al., 2006). In continuation of structural studies of thienyl derivatives (Prasath et al., 2010a;Prasath et al., 2010b), herein the title compound, bis- The asymmetric unit in (I), Fig. 1, comprises half a molecule with the full molecule generated by a crystallographic centre of inversion. The thiophene residue is co-planar with the imine group as seen in the value of the C2-C3-C5-N1 torsion angle of 6.5 (2) °. In fact the entire molecule is planar with the r.m.s. deviation for the 18 non-hydrogen atoms being 0.068 Å; the maximum deviations are found for the S1 [0.092 (1) In the crystal packing the molecules associate via C-H···N, C-H···π, [ Table 1] and S···S [S1···S1 i = 3.3932 (7) Å for i: Fig. 2.

Experimental
A mixture of ethylenediamine (0.6 g, 0.01 M) and 2-acetyl thiophene (0.7 g, 0.01 M) in dry benzene (50 ml) was refluxed using a Dean-Stark trap until no more water was collected (2 h). The benzene was then removed under reduced pressure and the residue treated with methanol. The solid that separated out was recrystallized from ethanol as colourless prisms.

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H = 0.95 to 0.99 Å, U iso (H) = 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation.

Computing details
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).     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-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.