Anionic Boron- And Carbon-Based Hetero-Diradicaloids Spanned By A P-Phenylene Bridge

Herein we report the synthesis and characterization of anionic boron- and carbon-based Kekule diradicaloids spanned by a p-phenylene bridge. In contrast to Thiele's hydrocarbon, a closed-shell singlet system, they show an appreciable population of the triplet state at room temperature, as evidenced by both NMR and EPR spectroscopy. Moreover, en route to these anionic boron- and carbon-based hetero-diradicaloids, the formation of an isolable diamino(4-diarylboryl-phenyl)methyl radical was observed.