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@C2v(6073)-C68 with the highest abundance on the temperature range of EMF formation instead of Sc2@C2v(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.