Dimerization of C-60 under the solid-state mechanochemical reaction conditions to give C-120 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 C-60 radical anion, and an equilibrium state is attained between C-60 and C-120. When the solid-state reaction was conducted under the catalysis of 4-aminopyridine, the formation of a small amount (similar to 4% yield) of fullerene trimer C-180 was also observed. The trimer C-180 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 C-180. The solid-state reaction of C-60 with C-70 in the presence of 4-aminopyridine afforded the cross-dimer C-130 in a low yield (similar to 2%) in addition to C-120 (6%). The dimer C-130 was also confirmed as the cyanated derivative by APCI MS spectroscopy, and was characterized by UV-vis and C-13 NMR spectroscopies. (C) 2000 Elsevier Science Ltd. All rights reserved.