5,12-Diselena-3,4,13,14-tetraazatricyclo[9.3.0.02,6]tetradeca-3,13-diene

The title compound crystallizes in a non-symmetrical conformation with a dihedral angle between the heterocycles of 45.0 (3)° and a nearly strain-free tetramethylene tether.

The selenadiazole rings in the title compound ( Fig. 1) are essentially planar and include a torsion angle of N13-C14-C4-N3 = À43.6 (10) . This torsion angle is significantly smaller than the corresponding torsion angle (58.2 ) in a dibenzocycloocta-1,3-diene (Janhsen et al., 2017). In the tetramethylene tether, the dihedral angle at C8-C9-C10-C14 [84.9 (10) ] shows the largest deviation from the ideal value of 60 whereas C6-C7-C8-C9 matches this value nearly perfectly: À59.7 (11) . Contrary to the formal symmetry, the conformer in the crystal shows neither a C 2 axis nor a mirror plane. Two molecules of the title compound fill the unit cell, and these are related by a center of inversion. One hydrogen atom at C7 points to the center of a selenadiazole of the neighbouring molecule, thus keeping the rings at a distance (Fig. 2).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. The crystal studied was nonmerohedrally twinned with a fractional contribution of 0.342 (3) for the minor twin component.

Figure 1
Perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Partial packing diagram of the title compound. View is along the b axis.
Spek, A. L. (2020 where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.68 e Å −3 Δρ min = −1.50 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

data-2
IUCrData (2020). 5, x201585 Refinement. Refined as a 2-component twin. Hydrogen atoms attached to carbons were placed at calculated positions and were refined in the riding-model approximation with C-H = 0.95 Å, and with U iso (H) = 1.2 U eq (C).