Electron-Transfer-Induced Substitution of Alkylated C₆₀ Chlorides with Proton Sponge

A series of alkylated C60 chlorides 1,4-RC60Cl (1) were found to undergo nucleophilic substitution with 1,8-bis(dimethylamino)naphthalene (2), affording 1,4-RC60Ar [3, Ar = 4,5-bis(dimethylamino)-1-naphthyl] in good yields. An SRN1 mechanism, initiated by a single-electron transfer from 2 to 1, is proposed on the basis of the enhanced rates compared with the rate of the SN1 reaction of 1 with anisole. The involvement of free radicals in the reaction is supported by the formation of a small amount of dimer RC60−C60R (4) as a byproduct. The enhanced ability of C60 chlorides 1 to accept an electron, attributable to the inductive effect of the directly attached chlorine atom, was demonstrated by its reduction potential and calculated LUMO energy.