Understanding the Reactivity of Ion-Encapsulated Fullerenes

Abstract

The influence of the encapsulation of an ion inside the C 60 fullerene cage on its exohedral reactivity was explored by means of DFT calculations. To this end, the Diels–Alder reaction between 1,3-cyclohexadiene and M@C 60 (M=Li + , Na + , K + , Be 2+ , Mg 2+ , Al 3+ , and Cl − ) was studied and compared to the analogous process involving the parent C 60 fullerene. A significant enhancement of the Diels–Alder reactivity is found for systems having an endohedral cation, whereas a clear decrease in reactivity is observed when an anion is encapsulated in the C 60 cage. The origins of this reactivity trend were quantitatively analyzed in detail by using the activation strain model of reactivity in combination with energy decomposition analysis