Deciphering the Role of Long-Range Interaction in Endohedral Metallofullerenes: A Revisit to Sc₂C₇₀

Structure elucidation is a vital step to study endohedral metallofullerene (EMF), and theoretical investigation is a useful complementary way to elucidate structures of EMFs. However, our recent work exposed that density functional theory (DFT) methods without long-range corrections are prone to overestimate energies of Sc₂C₂@C₇₂ isomers. In this work, the role of long-range interaction in energy estimation of EMFs was rigorously investigated by comparing energies and interaction energies of Sc₂C₇₀ and La₂C₉₆ series with wB97XD, M06-2X, B3LYP, and PBE0 methods, and it was disclosed that long-range interaction is ubiquitously imperative for metal cluster fullerenes and conventional metallofullerenes whose cages are absent of adjacent pentagon pair(s). Meanwhile, thermodynamic stabilities of the controversial Sc₂C₇₀ series were thoroughly investigated, and Sc₂C₂@<i>C</i>_<i>2v</i>(6073)-C₆₈ with the highest abundance on the temperature range of EMF formation instead of Sc₂@<i>C</i>_<i>2v</i>(7854)-C₇₀ was confirmed to be the experimentally isolated Sc₂C₇₀ isomer by DFT calculations combined with statistical mechanics and simulated UV–vis-NIR spectra. This work could provide instructive guidelines on structure elucidation of EMFs and investigation of reactivity of EMFs