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 BCl3 and an appropriate stannacyclic precursor, and the dehydrochlorination of the H2IMes adduct of the chloroborane product. Comparative structural, photophysical, and redox properties reveal narrow HOMO–LUMO gaps relative to the all‐carbon acene analogues. Just add boron: Synthetic routes to the N‐heterocyclic‐carbene‐stabilized 5‐boranaphthacene and 6‐borapentacene are described and complement that previously developed for 9‐boraanthracene. Comparative structural, photophysical, and redox properties reveal narrow HOMO–LUMO gaps relative to the all‐carbon acene analogues.