Study of Two Puzzled Questions on the Fullerene C70: A First-principles Study

The cycloaddition reactions of NH to different bonds on C-70 have been studied by the first-principles calculations. The results indicate that the reactivity of cycloaddition reactions is determined by the directional curvature, K-D, and the larger binding energy of E-b on the bond C-5-C'(5) can be ascribed to the unique bond which can be treated as the shortest bond of (5.5)-SWCNT in the four [6,6] ring fusion bonds. This work also discloses that the energy gap of different spin states is decided by the electronic density, and that of the frontier obitals for the bond C-5-C'(5) is larger than the value for the C-4-C'(4) bond. Furthermore, the transition state investigation of the two bond addition reactions provides a reaction barrier of 11.10 kcal/mol for the NH cycloaddition to the C-5-C'(5) bond; whereas, the addition reaction on C-4-C'(4) is a spontaneous pathway. Herein, the dynamics effect illustrates the [2+1] cycloaddition reaction on the equatorial C-5-C'(5) bond to be unfavorable.