TANDEM MASS-SPECTROMETRY STUDIES OF OXYGEN INTERACTIONS WITH FULLERENES AND METALLOFULLERENES

The reaction products of oxygen with fullerenes and metallofullerenes have been characterized by thermal desorption mass spectrometry and low energy collisional activation on a triple quadrupole mass spectrometer. C60O, which is present in fullerene soot, fragments primarily with the loss of O, although CO loss can be observed at higher collision energies. Fragmentation of C60On- adducts, formed by reactions with oxygen in the chemical ionization source or by reactive collisions with O-2 in the collision cell, is characterized by CO loss at relatively low energies, followed by CO2 loss and loss of 2CO. The results indicate that O-2 must interact as the intact diatomic species in order to initiate fragmentation of the fullerene cage, consistent with other reports in the literature. O-3 induced fragmentation occurs in a similar fashion, and the results may explain the first step in the recently reported formation of higher, odd-numbered fullerenes (e.g. C-119) in ozonolysis. Studies with metallofullerenes indicate that the extractable metallofullerenes (LaC82, La2C80) are less reactive toward oxygen than their less extractable counterparts (LaC60, LaC70). The stability of LaC82 and La2C80 was demonstrated by the formation of He uptake products (e.g. He@LaC82) in high energy collisions with He in a hybrid (BEqQ) mass spectrometer.