Mechanochemical Synthesis and Characterization of the Fullerene Dimer C120

• Published in: Journal of organic chemistry Vol. 63; no. 25; pp. 9358 - 9366
• Main Authors: Komatsu, Koichi, Wang, Guan-Wu, Murata, Yasujiro, Tanaka, Toru, Fujiwara, Koichi, Yamamoto, Kazunori, Saunders, Martin
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.12.1998
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo981319t

The bulk synthesis of the [2 + 2] dimer of fullerene C60 was achieved by the solid-state mechanochemical reaction of C60 with KCN by the use of a high-speed vibration milling (HSVM) technique. This reaction took place also by the use of potassium salts such as K2CO3 and CH3CO2K, metals such as Li, Na, K, Mg, Al, and Zn, and organic bases such as 4-(dimethylamino)- and 4-aminopyridine. Under optimum conditions, the reaction afforded only the dimer C120 and unchanged C60 in a ratio of about 3:7 (by weight) regardless of the reagent used. The dimer C120 was fully characterized by IR, UV−vis, 13C NMR, and TOF MS spectroscopies, cyclic voltammetry, and differential scanning calorimetry. Comparison of the IR and 13C NMR spectral data of C120 with those reported for all-carbon C60 polymers implied that the [2 + 2] dimer C120 represents the essential subunit of these polymers. The dimer C120 underwent facile dissociation into two C60 molecules by heat, HSVM treatment, exposure to room light, or electrochemical reduction. The dimer C120 encapsulating 3He in one of the C60 cages was synthesized and was used to confirm the scrambling of a C60 cage between the monomer and the dimer during the HSVM reaction. A possible mechanism for the selective formation of the dimer C120 is proposed.