C240 — The most chemically inert fullerene?

The reactivity of the fullerenes is primarily a function of their strain, as measured by the pyramidalization angle or curvature of the conjugated carbon atoms. The development of faceting in the structure of large icosahedral fullerenes leads to a minimum in the value of the maximum fullerene pyramidalization angle that lies in the vicinity of C240. On this basis it is argued that C240 will be the most chemically inert fullerene. This observation explains the production of [10,10] single-walled nanotubes because a C240 hemisphere is required for the nucleation of such tubes.