Counter anion in Li+‐encapsulated C60 can further enhance the rate of Diels–Alder reaction: A DFT study

Density functional theory calculations were carried out to investigate the Diels–Alder cycloaddition between cyclopentadiene and C₆₀ after the encapsulation of Li⁺ ion with transition states identified and confirmed by intrinsic reaction coordinate calculations. Our results showed that the Li⁺‐encapsulation results in a lower energy barrier and the presence of counter anion can further reduce the energy barrier, making the trend in agreement with the experimental results. In addition, the influencing factors on the reactivity of Li⁺‐encapsulated fullerenes such as counter anion and the position of Li⁺ in C₆₀ were discussed. This study aims to provide a better understanding of Diels–Alder reaction with Endohedral Metallofullerenes to allow more efficient functionalization of fullerenes.