Sc3N@C80: Computations on the Two‐Isomer Equilibrium at High Temperatures

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Abstract
Reported herein are computations on the relative concentrations of the two experimentally known isomers of Sc3N@C80 , that is, those produced by encapsulation of Sc3N in two particular C80 cages that obey the isolated‐pentagon rule, namely, with Ih and D5h symmetries. The calculations are based on density functional methods and have been carried out using the Gibbs energy over a broad temperature interval. It has been computed that, if a relatively free motion of the encapsulate inside the cages is allowed, the observed populations of 10 and 17 % for the D5h Sc3N@C80 species are reached at temperatures of 2100 and 2450 K, respectively. The inclusion of the entropy term is essential as, if it is neglected, the D5h Sc3N@C80 population at a temperature of 2100 K would be a mere 1 %, owing to the relatively large interisomeric separation potential energy of 19 kcal mol−1.