The quenching behaviour of the triplets of C, and Cl0 towards various nitroxide radicals has been investigated by the flashphotolysis technique. The quenching rate constants lie between I .9 x lo9 and 3.7 x lo9 M-' s-'. Possible quenching mechanisms are discussed.
1. Introdnctlon
The simple method of production of fullerenes such as CsO and Co in high yields [l-S ] and their availability from commercial sources have prompted many chemists to enter the field of fullererie chemistry [ 6-241. One of the long-term goals of this research is the preparation and characterization of derivatives of fullerenes which may have interesting properties. Any attempt in this direction should naturally make use of low reduction potentials of these compounds [ 10,12,13 1. The first reduction of Cd0 is observed at -0.42 V (versus SCE in acetonitrile) [ 121. Thus, reduction of fullerenes should be possible with potential electron donors with low ionization potentials. The radical anion of fullerene, generated from such an electron-transfer reaction, is a reactive intermediate and the choice of suitable reagents could trap this intermediate in the form of the desired product. However, very often generation of CG' and CG' may not be possible owing to unfavourable thermodynamic conditions. In such situations, the photoexcitation of fullerenes may provide the energy necessary for the electron-transfer reaction. Recently, there have been a number of studies which attempt to explore the electron accepting ca-