Regioselective [2 + 2] Cycloaddition of a Fullerene Dimer with an Alkyne Triggered by Thermolysis of an Interfullerene C–C Bond

Heating of a singly bonded fullerene dimer in the presence of an alkyne forms a cyclobutene structure on only one of the two fullerene moieties, through a stereo- and regioselective [2 + 2] cycloaddition. Experimental and theoretical data suggest that the reaction is triggered by cleavage of the interfullerene C–C bond and formation of a monomeric fullerene radical.