Quantum-Chemical Modeling of Two Er3N@C-80 Isomers

Computations of the molecular parameters and relative populations are reported for the two isomers of Er3N@C-80 experimentally known, i.e. produced by encapsulation into the isolated-pentagon-rule (IPR) C-80 cages with I h and D 5h symmetries. The calculations are mostly based on the density-functional theory (DFT) treatments with the B3LYP functional. However, the inter-isomeric energetics is further refined with the B2PLYP method which places the D 5h endohedral higher in the potential energy by 18.8 kcal/mol. The isomeric populations are evaluated using the Gibbs energy in a broad temperature interval. The computations performed with the floating-encapsulate-model (FEM) treatment agree with the observation that Er3N@I h (7)-C-80 represents the major isomer. The calculations also suggest some similarity between (ErN)-N-3@C-80 and Lu3N@C80 so that Er3N@C-80 could possibly also produce a useful nanowire, like recently found with Lu3N@C80 and its interesting electrical-conductivity and switching behavior.