Crystal and molecular structure of 1-chlorobenz[a]phenazine-7N-oxide

Crystals of 1-chlorobenz[a]phenazine-7N-oxide, C₁₆H₉N₂OCl, are orthorhombic,a =15·04,b = 3·91,c = 20·50 Å,Z = 4, space groupPna2₁. The crystal structure has been determined from two- and three-dimensional X-ray photographic data and refined by Fourier and least-squares methods toR = 0·095 for 715 observed reflexions. The molecule is slightly non-planar. Bond lengths and angles compare well with those of other molecules. Close molecular packing is given by layers of molecules parallel to (001) plane.We are grateful to Professor V. Riganti for assistance with the data collection.