Stepwise Reduction of 9,10‐Bis(dimesitylboryl)anthracene

Stepwise reduction of 9,10-bis(dimesitylboryl)anthracene afforded an radical anion and a dianion, accompanied by stepwise changes of the aromaticity of the anthracene moiety. The radical has a planar semiquinoidal structure, while the dianion has a puckered quinoidal structure. The alteration of the geometries of the 9,10-bis(dimesitylboryl)anthracene upon reduction is rationalized by the nature of the bonding. These results have been confirmed by cyclic voltammetry, X-ray crystallography, NMR, EPR, and UV-vis-NIR spectroscopy, as well as DFT calculations.