THE FULLERENES - PRECURSORS FOR 21ST-CENTURY MATERIALS

The fullerenes represent a new molecular form of carbon. Their remarka ble physico-chemical properties make them desirable as components in n ew materials, and in order to exploit these properties it is necessary to understand the principles for the preparation of both pure buckmin sterfullerene (C60) derivatives of known addition number and pattern, and C60 containing materials of known composition and structure. C60 i s brominated by Br2 in a variety of solvents to give either C60Br6 or C60Br8, depending upon the particular solvent used. Crystals of C60Br6 .Br2.CCl4, C60Br6.xBr2 (x almost-equal-to 2), and C60Br8.xBr2 (x - 2) are obtained from CCl4, C6H6, and CS2 respectively. Reaction Of C60 wi th ICl yields C60Cl6, which has the same addition pattern as C60Br6. C ocrystallisation of C60 and I2 from C6H5CH3 solution yields the interc alate C60.I2.C6H5CH3 which contains discrete C60 and I2 molecules. Slo w evaporation Of C6H6 solutions of C60 gives crystals of the solvate C 60.4C6H6. Mixing of saturated C6H6 solutions of C60 and (eta5-C5H5)2Fe gives a dark red solution from which black crystals of C60.2[(eta5-C5 H5)2Fe] are deposited. In a similar manner cocrystallisation of C60 an d (eta5-C5H5)4Fe4(CO)4 from C6H6 solution yields black crystals of the intercalate C60.(eta5-C5H5)4Fe4(CO)4.3C6H6.