LAUSR

Density functional theory calculations have been carried out to investigate the [2 + x] x = 1, 2, and 3 cycloaddition reactions (paths A, B, and C) of triatomic sulfur (S3) with the C70 fullerene in terms of geometry, energies, and electronic structures. The thiozonation (S3) on the hexagon–hexagon and hexagon–pentagon bonds of the C70 fullerene through 1,3-dipolar reaction, i.e., [2 + 3] cycloaddition, is generally exothermic, while through the chelotrope additions, i.e., [2 + 1] cycloaddition, are endothermic. The results indicate that the 1,3-dipolar cycloaddition is the most preferable path. Having more negative values of reaction energies Er together with the lower barrier heights, thiozonation of the hexagon–hexagon bonds is thermodynamically and kinetically more favorable than hexagon–pentagon ones. Moreover, the addition of thiozone to the hexagon–hexagon bonds near the pole area of the C70 leads to more negative reaction energies. Therefore, it is established that the arrangement and position of C=C bonds play an important role in the thiozonation of C70 fullerene. Thiozonolysis of triatomic sulfur (S3) indicates that S–S bond cleavage has not occurred, instead a sulfur bridge over a C–C bond or a four-membered ring of 1,2-dithietane-1-sulfide is preferred to be formed.