Reactivity of the superhalogen/superalkali ion encapsulating C60 fullerenes

The Diels–Alder cycloaddition reaction between 1,3-cyclohexadiene and a series of C60 fullerenes with encapsulated (super)alkali/(super)halogen species (Li+@C60, Li2F+@C60, Cl−@C60, and LiF2−@C60) was explored by means of DFT calculations. The reactivity of the ion encapsulating systems was compared to that of the parent C60 fullerene. Significant enhancement in reactivity was found for cation-encapsulating Li+/Li2F+@C60 complexes. The cycloadduct formed by LiF2−@C60 was found to be the most thermodynamically favorable among the studied ones. In contrast, encapsulation of Cl− anions disfavors the cycloaddition reaction both kinetically and thermodynamically. Higher activation energy barrier and less stability of the reaction product in the case of Cl−@C60 were associated with the higher deformation energies of the fullerene cage and the lower interaction energy between the reactants in comparison with the other studied complexes.