Calculated Equilibrium Populations of Ti2C2@C82 Isomers

Abstract

High-temperature equilibrium relative populations of two Ti2C2@C82 isomers isolated recently are treated by quantum-chemical calculations, viz. endohedrals with the C s (c);6-C82 and C 3v (b);8-C82 IPR (isolated-pentagon-rule) cages. The calculations are carried out using the Gibbs energy based on the MP2=FU/6-31+G*∼SDD energetics and B3LYP/6-31G*∼SDD entropy. The observed ratio Ti2C2@C s (c);6-C82 : Ti2C2@C 3v (b);8-C82=1.6:1 is in the computations obtained at a temperature of 1543 K, i.e., in the supposed synthetic temperature region. Before that point, the two isomers reach their equimolarity at a temperature of 983 K. This fine theory-experiment agreement represents another example of a good performance of the Gibbs-energy based quantum-chemical evaluations of the fullerenic equilibrium compositions under the high-temperature synthetic conditions.