Exohedral Reactivity Principles

Like CgQ most of the characterized higher fullerenes can be considered as electron-deficient polyenes. They exhibit similarities in their chemical behavior [1-3]. Preferred primary addition reactions are, for example, addition of nucleophiles, as well as cycloadditions at the bonds adjacent to two six-membered rings ([6,6]-bonds). The most important difference from the chemistry of Cgg is due to the less symmetrical cages of the higher fullerenes, which exhibit a broad variety of bond environments with unequal reactivity towards addition reactions. Consequently 

This isomer represents the first example of a [5,6]-adduct in which the fusion bond remains intact. This addition mode was explained by the relatively high double bond character of the [5,6]-bond C(7)-C(8), which underlines the importance of the Kekule structure of C7Q that involves the benzenoid hexagons at the equatorial belt. No such resonance structure is required to describe the proper bonding situation within C50 (see also Chapters 1 and 14). 

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