Synthesis of hexahalogeno-1,8-diazabiphenylenes; separation of steric and electronic effects in extrusion of dinitrogen from benzo[c]cinnoline system, and the X-ray crystal structure of octachlorobenzo[c]cinnoline

Abstract

Thermal extrusion of dinitrogen from hexafluoro- and hexachloro-4,5,9,10-tetra-azaphenanthrenes gives hexafluoro- and hexachloro-1,8-diazabiphenylenes under conditions which contrast with the relatively easy dediazatation of octachlorobenzo[c]cinnoline whose X-ray crystal structure shows severe distortion.