Chemistry of Convex versus Concave Carbon: The Reactive Exterior and the Inert Interior of C₆₀

Abstract

Do the chemical properties of the surface of a carbon sheet depend on its shape? This question addresses a criterion for chemical behaviour that has hardly been investigated previously. The current neglect of this question may be due to the fact that suitable model systems with easily distinguishable graphitic surfaces were essentially unknown until the discovery [1] and synthesis [2,3,4] of fullerenes, nanotubes and other related forms of carbon. In this study, we present the first systematic comparison of the chemical behaviour of the convex outer and the concave inner surfaces of C₆₀ by analysing the results of semiempirical and DFT calculations on exohedral and endohedral complexes with H- and F-atoms as well as with the methyl radical. We show that such extremely reactive species are trapped by the extraordinary inert inner surface of C₆₀ and do not undergo chemical reactions.