Reactivity of the superhalogen/superalkali ion encapsulating C60 fullerenes

Abstract

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.