5b,7b-Diaza-3b,9b-diborabenzo[  ghi  ]perylenes

Treatment of a precursor to the chelating Lewis acid 2,2′-diborabiphenyl with 2,6-bisalkynyl-substituted pyridazines, leads to elimination of 2 equiv. of ClSiMe 3 ; subsequent treatment of the mixture with PtCl 2 catalyzes the cyclization of observable intermediates to the title 5b,7b-diaza-3b,9b-diborabenzo[ghi]perylene compounds in low isolated yields. The compounds were characterized by NMR and UV–vis spectroscopies, and in one case, by X-ray crystallography. NICS(1) computations indicate that the inner ring is less aromatic than the outer rings.