Decatungstate-Photocatalyzed Radical Addition of 9-Substituted Fluorenes to [60]Fullerene: A Mechanistic Approach

An innovative, efficient, regioselective functionalization of C-60 with 9H-fluorenes has been disclosed. This efficient photochemical approach uses certain fluorenyl radicals in 9-position deriving from fluorenes through a hydrogen-atom transfer (HAT) process mediated by tetrabutylammoniumdecatungstate [(n-Bu4N)(4)W10O32]. The single addition of these fluorenyl radicals to C-60 proceeded to produce [60]fullerene-fluorene dyads in a single step. The scope and mechanism of this new reaction have been examined. The primary kinetic isotope effect measurements signify the presence of a stepwise mechanism in which the C-H (D) bond scission is the rate-limiting step of the reaction.