THE STRUCTURE OF BUCKMINISTERFULLERENE COMPOUNDS

The fullerenes represent a new molecular form of carbon which has remarkable physico-chemical properties, making them desirable as components in new materials. An understanding of the principles for the preparation of both pure buckminsterfullerene (C60) derivatives of known addition number and pattern, and C60-containing materials of known composition and structure, is necessary for the development of fullerene chemistry. C60 is 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.Br2(x almost-equal-to 2) are obtained from CCl4, C6H6, and CS2 respectively. Reaction of C60 with ICl in C6H6 yields C60Cl6, which is isostructural with C60Br6. Reaction of C60Cl6 under Friedel-Crafts conditions with C6H6 results in the formation of C60Ph5Cl which is converted into C60Ph5H by reaction with PPh3 in C6H6. C60 undergoes a cycloaddition with C5H6 yielding C60C5H6 which is stabilished with respect to the retro Diels-Alder reaction by either hydrogenation or bromination of the pendant C5H6 moiety to give C60C5H8 and C60C5H6Br2 respectively. Cocrystallisation of C60 and I2 from C6H5CH3 solution yields the solvated intercalate C60.I2.C6H5CH3 which contains discrete C60, I2 and C6H5CH3 molecules. Slow evaporation of C6H6 solutions of C60 gives crystals of C60.4C6H6. Mixing of saturated C6H6 solutions of C60 and (eta5-C5H5)2Fe gives a dark red solution from which black crystals of C60.2[(eta5-C5H5)2Fe] are deposited. In a similar manner cocrystallisation of C60 and (eta5-C5H5)4Fe4(CO)4 from C6H6 solution yields black crystals of the intercalate C60.(eta5-C5H5)4Fe4(CO)4.3C6H6.