The fullerene dimer C120 and related carbon allotropes Original Research Article

Dimerization of C60 under the solid-state mechanochemical reaction conditions to give C120 was found to occur in the presence of potassium salts such as KCN, KOH, and KOAc, or of a small amount of alkali metals, or even of organic solid amines such as 4-aminopyridine. The reaction is presumed to involve the formation of the C60 radical anion, and an equilibrium state is attained between C60 and C120. When the solid-state reaction was conducted under the catalysis of 4-aminopyridine, the formation of a small amount (∼4% yield) of fullerene trimer C180 was also observed. The trimer C180 was confirmed as its cyanated derivative by APCI MS spectroscopy, and was characterized by IR and UV–Vis spectroscopies. Based on the results of HPLC analyses, there are at least four isomers of C180. The solid-state reaction of C60 with C70 in the presence of 4-aminopyridine afforded the cross-dimer C130 in a low yield (∼2%) in addition to C120 (6%). The dimer C130 was also confirmed as the cyanated derivative by APCI MS spectroscopy, and was characterized by UV–vis and 13C NMR spectroscopies.