Eu@C88 Isomers: Calculated Relative Populations

Abstract

Relative populations of three energy-lowest IPR (isolated-pentagon-rule) isomers of Eu@C88 are computed using the Gibbs energy based on characteristics from density functional theory and MP2 calculations (M06-2X/3-21G∼SDD entropy term, and the MP2=FU/6-31G*∼SDD or B2PLYPD=FU/6-31 + G*∼SDD energetics). The calculations predict coexistence of three isomers, in agreement with extraction using a polar solvent, and offer a possible explanation why the Eu@C 2(27)-C88 species should prevail with a non-polar solvent. Role of extraction solvents and catalysis is thus pointed out.