Snaith group

Abstract:

Two Er@C₈₂ isomers have been isolated and unambiguously characterized as Er@ C_{2 v}(9)-C₈₂ and Er@ C _s(6)-C₈₂, respectively, by single-crystal X-ray diffraction. Er@ C _s(6)-C₈₂ is identified as a dimeric structure in the crystalline state, but dimerization does not occur for Er@ C_{2 v}(9)-C₈₂ under identical crystallization conditions, indicating a cage-symmetry-induced dimerization process. Density functional theory calculations reveal that the major unpaired spin resides on a special C atom of Er@ C _s(6)-C₈₂, which leads to regioselective dimerization. Calculations also found that the dimeric structure of Er@ C _s(6)-C₈₂·Ni(OEP) is much more stable than the two monomers, suggesting a thermodynamically favorable dimerization process. Vis-near-IR spectrometric and electrochemical results demonstrate that the electronic structure of Er@C₈₂ isomers is Er³⁺@C₈₂^3-, instead of the theoretically proposed Er²⁺@C₈₂^2-.