Calculated relative populations of Sm@C₈₂ isomers

ABSTRACT

Relative populations of the four observed IPR (isolated-pentagon-rule) isomers of Sm@C₈₂ are computed using the Gibbs energy derived from partition functions supplied with parameters from DFT (density functional theory) calculations (the M06/6-311+G*∼SDD energy and M06/3-21G∼SDD entropy part). At a temperature of 1750 K, for example, the recommended calculated concentration ratios are: Sm@C_2v(9)-C₈₂ : Sm@C_s(c; 6)-C₈₂ : Sm@C₂(c; 5)-C₈₂ : Sm@C_3v(a; 7)-C₈₂ = 43.4 : 34.4 : 20.3 : 1.8, though the results are sensitive to the partition-function description. The observed dependency of the Sm@C₈₂ isomeric productions on the applied metal source could be related to kinetic and catalytic aspects (that influence the degree of inter-isomeric thermodynamic equilibrium) and/or to different solubility.

KEYWORDS:

• Sm@C₈₂
• metallofullerenes
• DFT computations
• isomeric populations
• Gibbs-energy evaluations
• IPR fullerene cages

Acknowledgments

The reported research has been supported by the Czech Science Foundation/GACR (P208/10/0179), including the access to the MetaCentrum (LM2010005) and CERIT-SC (CZ.1.05/3.2.00/08.0144) computing facilities; by the Charles University Centre of Advanced Materials/CUCAM (CZ.02.1.01/0.0/0.0/15_003/0000417); by the NSF of China (21171013, 51372158, 21471010), and by the Ministry of Science and Technology of China (Nos. 2013CB933402, 2011CB932601).