Abstrakt
Relative populations of the four observed IPR (isolated-pentagon-rule) isomers of Sm@C-82 are computed using the Gibbs energy derived from partition functions supplied with parameters from DFT (density functional theory) calculations (the M06/6-311+G*approximate to SDD energy and M06/3-21G approximate to SDD entropy part). At a temperature of 1750 K, for example, the recommended calculated concentration ratios are: Sm@C-2v(9)-C-82 : Sm@C-s(c; 6)-C-82 : Sm@C-2(c; 5)-C-82 : Sm@C-3v(a; 7)-C-82 = 43.4 : 34.4 : 20.3 : 1.8, though the results are sensitive to the partition-function description.
The observed dependency of the Sm@C-82 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.