Radical Cation and Dication of Fluorene Fully Annelated with Bicyclo[2.2.2]octene Units: Importance of the Quinoidal Resonance Structure in the Cationic Fluorene
annelated with bicyclo[2.2.2]octene units was newly synthesized and oxidized to stable cationic species. The structure of radicalcation salt 1(.+)SbCl(6)(-) was determined by X-ray crystallography, while the first fluorene dication 1(2+) was characterized by (1)H and (13)C NMR at -80 degrees C. Combined with the results of theoretical calculations, an important contribution of a quinoidal structure to the