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.
Fluorene 1 fully annelated with bicyclo[2.2.2]octene units was newly synthesized and oxidized to stable cationic species. The structure of radical cation 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 resonance hybrid was demonstrated in both 1(.+) and 1(2+). [structure: see text]
Nishinaga
Tohru
T
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Inoue
Ryota
R
Matsuura
Akira
A
Komatsu
Koichi
K