Ozonization of C70 and subsequent thermolysis of ozonide 1,2-C70O3:: A theoretical study

Semiempirical method AM1 was employed to investigate the ozonization of [70]fullerene (C-70) and the following extrusion of molecular oxygen from ozonide 1,2-C70O3. Our computational results show that (i) among the eight different bonds of C-70 that may react with ozone, the C-1-C-2 and C-5-C-6 bonds are the two most active pair sites with near the same energy barriers; (ii) there are six different pathways to extrude molecular oxygen from ozonide 1,2-C70O3, of which one results in 1,6-oxidoannulene, one affords 2,3-oxidoannulene, the other four lead to 1,2-epoxide. It is most likely that the formation of 1,2-epoxide proceeds via two parallel routes with similarly lower-energy profiles, which are favored both thermodynamically and kinetically. Several new intermediates and transition states have been located for the thermolysis of ozonide 1,2-C70O3 to epoxide 1,2-C70O. Four steps are required for the seemly simple conversion of 1,2-C70O3 to 1,2-C70O. (C) 2008 Elsevier B.V. All rights reserved.