X-ray crystal structure of -bis-(pyridin-3-yl)ethyl-ene: comparing the supra-molecular structural features among the symmetrical bis-(-pyrid-yl)ethyl-enes ( = 2, 3, or 4) constitutional isomers.

The mol-ecular structure of -bis-(pyridin-3-yl)ethyl-ene (), CHN, as determined by single-crystal X-ray diffraction is reported. The mol-ecule self-assembles into two dimensional arrays by a combination of C-H⋯N hydrogen bonds and edge-to-face C-H⋯ inter-actions that stack in a herringbone arrangement perpendicular to the crystallographic -axis. The supra-molecular forces that direct the packing of as well as its packing assembly within the crystal are also compared to those observed within the structures of the other symmetrical isomers -1,2-bis-(-pyrid-yl)ethyl-ene ( , , where = ' = 2 or 4).