The metal chemistry of the carbahemiporphyrazines

Over fifty years ago, Linstead and Elvidge described the syntheses of phthalocyanine-like macrocycles in which one or two of the interior metal-binding nitrogen atoms were replaced with aromatic C-H groups. We review here the coordination chemistry of two of these systems, dicarbahemiporphyrazine and benziphthalocyanine, and we emphasize the unusual reactivity displayed by these macrocycles and the varying extent to which the C-H groups are activated by metal-binding.