Extensive Structural Rearrangements upon Reduction of 9H-9-Borafluorene

摘要

Common wisdom has it that organoboranes are readily oxidized. Described herein is that also their reduction can result in remarkable chemistry. Treatment of dimeric 9H-9-borafluorene with Li metal in toluene yields two strikingly different classes of compounds. One part of the sample reacts in a way similar to B2H6, thus affording an aryl(hydro)borane cluster reminiscent of the [B3H8]~- anion. The other part furnishes a dianionic boron-doped graphene flake devoid of hydrogen substituents at the boron centers and featuring a central B=B bond. A change in the solvent to THF allows an isolation of this dibenzo[g,p]chrysene analogue in good yields.