Molecular Packing in Crystals of Phenoselenazine

The crystal structure of phenoselenazine was solved by molecular-packing analysis. Trial models of the rigid molecule were oriented and positioned in the Cheshire cell. The refinement was carried out by structure-factor least-squares calculations using individual anisotropic temperature factors. The final discrepancy index was R = 0.051 for 601 reflexions which were more than two standard deviations above background. The unit cell with a= 7.829 (5), b = 20.909 (4) and c= 5.927 (7)/~ contains four molecules. The space group is P2~2121. The molecule has the same folded configuration as phenothiazine but is more open. The dihedral angle is 149"6 ° .