Synthesis and comparative characterization of 9-boraanthracene, 5-boranaphthacene, and 6-borapentacene stabilized by the H2IMes carbene.

A general procedure for the preparation of three N-heterocyclic carbene stabilized, boron-containing acenes (9-boraanthracene, 5-boranaphthacene, and 6-borapentacene) is presented. The key steps involve a transmetallation reaction between BCl(3) and an appropriate stannacyclic precursor, and the dehydrochlorination of the H(2)IMes adduct of the chloroborane product. Comparative structural, photophysical, and redox properties reveal narrow HOMO-LUMO gaps relative to the all-carbon acene analogues.