ADDITION CHEMISTRY OF C-60 - A THEORETICAL-ANALYSIS OF SUBSTITUTIONALPREFERENCES FOR HALOGENATION AND HYDROGENATION OF C-60

Reactions involving C-60 With a variety of species have produced a ser ies of new fullerene derivatives. Such reactions include hydrogenation , methylation, halogenation, and epoxidation to name a few. The observ ed reaction chemistry traces the chemistry of aromatics in some cases; however, in others it is considerably less well understood. In this w ork, our efforts are directed at understanding mechanistic concerns in halogenation. To date several studies have analyzed the energetics of fluorination, bromination, and hydrogenation without serious consider ation of orbital mechanism or isomer preferences. In this work, the or bital mechanism for reactivity is assessed for addition of halogens. T he site preference for addition is analyzed with respect to symmetry d istinct sites in C-60 These include the well-described 6-6' and 5-6' s ites in C-60 The site directed preference for subsequent additions is discussed as well. Different site preferences are observed for F and B r; the effects are due to orbital driven reaction chemistry and thermo dynamic stabilities of products. ''Ortho'' substitution appears favore d for F substitution while 1,3 or 1,4 product predominants for Br addi tion.