Electron-Transfer Promoted Substitution of Alkylated C₆₀ Chlorides by Proton Sponge

Abstract

A series of alkylated C60 chlorides 1,4-RC₆₀Cl (1, R = CH₂Cl, CHCl₂, CCl₃) were found to undergo nucleophilic substitution with 1,8-bis(dimethylamino)naphthalene (2), affording 1,4-RC₆₀Ar [Ar = 4,5-bis(dimethylamino)-1-naphthyl] in good yields. An S_RN1 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 S_N1 reaction of 1 with anisole. The involvement of radicals in the reaction is supported by the formation of a small amount of dimer RC₆₀-C₆₀R 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 oxidation potential and calculated HOMO energy.