Quantum\nChemical Insight into Metallofullerenes M₂C₉₈: M₂C₂@C₉₆ or\nM₂@C₉₈, Which Will Survive?

Abstract

Systematic studies on M₂C₉₈ (M = Sc, Y, La,\nGd, Lu) series by means of density functional theory (DFT) methods\ndisclose that having large concentrations within the temperature interval\nof fullerene formation, the metal–carbide endohedral fullerenes\nM₂C₂@C₉₆ are found to be more stable\nthan the dimetallofullerenes M₂@C₉₈. When encapsulating\nM₂C₂ clusters, three types of C₉₆ cages will present excellent thermodynamic stabilities and become\nthe largest metal–carbide endohedral fullerenes so far. The\ndynamic mechanisms of the internal C₂ moieties in the most\nimportant M₂C₂@C₉₆ species have been\ndiscussed, which provide profound understanding of metal–carbide\nendohedral fullerenes. Moreover, ¹³C NMR and IR spectra\nhave been simulated to aid further experimental identification and\ncharacterization.