3,14-Diselena-4,5,12,13-tetra-aza-tri-cyclo-[9.3.0.0(2,6)]tetra-deca-1(11),2(6),4,12-tetra-ene

The crystal structure of the third isomer of cyclooctenobis-1,2,3-selenadiazoles, C(8)H(8)N(4)Se(2), is reported. The mol-ecule is located on a twofold rotation axis. The eight-membered ring adopts a twist-chair conformation with planar heterocycles. C-H⋯N hy-dro-gen bonds connect the mol-ecules into layers parallel to (101).