Tetrakis(bicyclo[2.2.2]octeno)cyclooctatetraene dication: a stable COT dication with a tub structure

One–electron oxidation of the radical cation of tetrakis(bicyclo[2.2.2]octeno)cyclooctateraene with SbF5 gives the corresponding dication, a tub-shaped eight-membered ring, which rapidly inverts with an energy barrier of 10.8 ± 0.7 kcal mol–1.