Bond length effect on odd-electron behavior in single-walled carbon nanotubes

A view of the single-walled nanotube reactivity based on unpairing odd electrons is suggested. It is shown that in the framework of the UHF single-determinant approach, the electron unpairing critically depends on the corresponding interatomic C-C distance, and as a result of the dependence, a perfect (4,4) nanotube should be attributed to species with intermediate radical behavior. The distribution of effectively unpaired electron density over tube atoms coincides with that of the free valency and serves as a quantitative indicator of the tube atom chemical susceptibility. Comparison with the C 6o fullerene points to a higher reactivity of the tube both at its cap and side wall. The effect of (5-7) defects on the tube reactivity is discussed. © 2007 American Chemical Society.