| A new synthetic method for high purity 6,5-open and 6,6-closed methanofullerenes has been developed using the reaction between the lithium salt of a tosyhydrazone with C60. The 6,5-open methanofullerene can be converted to 6,6-closed methanofullerenes at elevated temperature in the presence of ambient light. After careful kinetic study, this conversion was found to be photoassisted. A mechanism involving a triplet state opening to a biradical is proposed. The triplet state can be quenched by oxygen generating singlet oxygen which can be trapped by tetramethyl ethylene. The NMR spectra provided conclusive evidence for the interconversion of the two 6,5-open isomers confirming the biradical intermediate.; The reaction between lithium salt of tosyhydrazones and C60 was applied to synthesize fullerene derivatives of steroids. Two equal mole 6,5-open isomers were observed in these reactions. When the reaction was carried out in the absence of light, one 6,5-open isomer, in which the bulky steroid group is above five membered ring, is the dominate product (97%). The product distribution can be changed dramatically by exposing the reaction to ambient light.; The reaction of fullerene-60 with 1,3-dihydrobenzo(c) thiophene 2,2-dioxide and its derivatives was found to be a versatile way to derivatize fullerene. Variable temperature NMR was used to evaluate the stereo-electronic interaction between fullerene and the substituent.; The Diels-Alder reaction between cyclooctatetraene with fullerene has been carried out. The relationship between the chemical shift and the position of protons in the substituent has been evaluated. |
