Typical Reactions of Fullerenes

For hollow objects like the fullerenes, a general distinction has to be made between outside and inside reactivity. Modifications to the outside are termed exohedral functionalization, and those to the inside are endohedral. Both variants are observed for the fullerenes. Classical fullerene chemistry deals with exohedral functionalization by one or more groups attached to the carbon atoms. Endohedral chemistry, on the other hand, studies compounds consisting of atoms or small molecules included in the cavity within the fullerene cage. The exohedral processes may further be divided into covalent and noncovalent interactions with the reaction partner. 

Apart from the nucleophilic addition, also radical reactions can occur on the surface of the fullerenes. These act as a sponge for radicals which are easily added, yielding dia- or paramagnetic products. Dimers of fullerenes are frequently obtained as well in this kind of reaction. 

Moreover, pericycUc reactions like [4+2]-, [3+2]-, and [2+2]-cycloadditions, to name the most prominent, are observed for C o and also for higher fullerenes. In these cases, Co, may be reacted with electron-poor as well as with electron-rich species. The cycloaddition chemistry of fullerenes yields a wide spectrum of valuable derivatives that may be employed to the production of new, further functionalized materials (refer to Section 2.5.5.3). 

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