2-[(E)-(Pyridin-2-ylmethylidene)amino]thiophene-3-carbonitrile

In the title compound, C11H7N3S, the thiophene and pyridine rings are coplanar, forming a dihedral angle of 3.89 (7)°. The conformation about the C=N bond [1.2795 (18) Å] is E. In the crystal, translationally related molecules along the a axis form weak π–π interactions [centroid–centroid distance = 3.8451 (8) Å] between the thiophene rings.


Comment
Title compound (I) was made during our ongoing research on azomethine materials. It is one of a limited number of reported crystal structures of pyridine azomethine derivatives. The structure was confirmed by the X-ray crystallography as shown in Fig. 1. The ORTEP diagram shows that the structure adopts the thermodynamically stable E isomer. The planes described by the thiophene and the pyridine moieties form a dihedral angle of 3.89 (7)° between each other.
A view of the crystal packing for (I) is illustrated in Fig. 2. Molecules stack along the a axis forming weak π-π interactions [3.8451 (8) Å for symmetry operation -1+x, y, z] formed between translationally related thiophene rings.

Experimental
In a round bottom flask, 2-pyridinecarboxaldehyde (200 mg, 1.91 mmol) and 2-amino-3-cyanothiophene (260 mg, 2.08 mmol) were dissolved in anhydrous ethanol (25 mL). A catalytic amount of trifluoroacetic acid was added to the mixture and it was stirred at 80°C under nitrogen for 20 h. The reaction was then cooled to room temperature and the resulting product filtered to get the title compound as a yellow crystals (155.9 mg, 38%).

Refinement
H atoms were placed in calculated positions (C-H = 0.93 Å) and included in the refinement in the riding-model approximation, with U iso (H) = 1.2U eq (C).  Molecular structure with the numbering scheme adopted and ellipsoids drawn at 30% probability level.

Figure 2
A view of the unit cell contents for (I).

Special details
Experimental. X-ray crystallographic data for I were collected from a single-crystal sample, which was mounted on a loop fiber. Data were collected using a Bruker Platform diffractometer, equiped with a Bruker SMART 4 K Charged-Coupled Device (CCD) Area Detector using the program APEX2 and a Nonius FR591 rotating anode equiped with a Montel 200 optics The crystal-to-detector distance was 5.0 cm, and the data collection was carried out in 512 x 512 pixel mode. The initial unit-cell parameters were determined by a least-squares fit of the angular setting of strong reflections, collected by a 10.0 degree scan in 33 frames over four different parts of the reciprocal space (132 frames total). One complete sphere of data was collected, to better than 0.80 Å resolution. 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-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.