Computations of the Catalytic Effects in the Stone-Wales Fullerene Isomerizations:N and CN Agents

摘要

The Stone-Wales rearrangement has long been considered as a plausible,albeit hypothetical,mechanism for fullerene annealing and isomerizations.In the view of a recently applied new catalyst,KCN,for incorporation of noble gases in fullerenes,the CN radical is studied here computationally as a possible catalytic species acting in kinetics of the Stone-Wales fullerene transformation,and a possible role of K~+ is also investigated.The computations are performed on the PM3-optimized bowl-shaped model C__(34)H_(12) to which the CN radical is attached by its C or N atom.The activation energies are evaluated at the UPM3,UHF/6-31G~*,UB3LYP/6-31G~*,ROB3LYP/6-31G~*,ROHF/6-31G~**,and ROB3LYP/6-31G~** levels.However,the reduction of the kinetic barrier owing to the catalyst action is modest so that a free N atom,neutral or charged,still remains a more efficient option.Effects of negatively charged CN species and of K+ are also found insufficient.Small amounts of nitrogen are indeed always present during fullerene synthesis,especially from He gas.