The long-standing mystery behind the structure formed by the highly reduced fullerene fragment, the corannulene tetraanion C20H104-, is now resolved. Single-crystal X-ray diffraction analysis of its lithium salt confirms the formation of a sandwich-type supramolecular aggregate with a high degree of alkali metal intercalation. In contrast to the previously proposed model, it is now revealed that five Li+ ions are sandwiched between the two tetrareduced corannulene decks to form the supramolecular dimer both in solution and in the solid state. These results establish a new paradigm for lithium intercalation between the curved carbon surfaces of buckybowls, fullerenes, and nanotubes.  Moreover, the above corannulene anion having one electron per five carbon atoms is more electron rich than the fullerene-hexaanion (one electron per ten carbon atoms). Structural deformations caused by adding multiple electrons to a bowl-shaped polyarene as well as transformations of the resulting supramolecular aggregate in different solvents will be discussed.

Self-assembly of highly charged corannulene:   Structural mystery resolved

243rd National Meeting (2012)

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