Stability calculations for Eu@C_(74) isomers

摘要

Density functional theory (DFT) calculations are reported for Eu@C _(74), where the considered C_(74) cage is either the IPR (isolated pentagon rule) species or two cages with a pentagon-pentagon junction. Their relative thermodynamic production yields are evaluated using the DFT calculated terms and it is shown that the IPR-based Eu@C_(74) endohedral prevails at relevant temperatures in agreement with observation, however, isolation of a minor isomer should be possible. The question of whether C _(74)-based metallofullerenes present isomeric forms is still an object of debate. In the case of Eu@C_(74) density functional theory calculations predict that in addition to the dominant endohedral species (in which none of the pentagons in the C_(74) cage make contact with each, in respect to the isolated pentagon rule, IPR), a non-IPR isomer should exist and could possibly even be isolated.