Crystalline Radical Anion of a Diboratriazole and Its Conversion to a Neutral Radical Driven by a Carbene.

One-electron reduction of diboratriazole with potassium graphite (KC) generates the radical anion •, which undergoes a salt (KCl) elimination reaction upon addition of an -heterocyclic carbene (NHC) to afford the neutral diboratriazole radical . An X-ray diffraction analysis, electron paramagnetic resonance spectroscopy, and computational studies revealed that an unpaired electron in radical species and is delocalized over the π-system of the BN and carbene rings. Reversible oxidation of gives rise to a diboratriazole cation featuring a 6π aromatic character. Moreover, treating with a half equivalent of a bis(NHC) produces a biradical species , in which there is little interaction between two radical moieties separated by the bis(NHC) linker, suggesting the dis-biradical property. undergoes stepwise and reversible two-electron oxidation, establishing three formal oxidation states.