Hyperfluorination of buckminsterfullerene: cracking the sphere

Our recent experiments on the fluorination of C[sub 60] (carried out in pursuit of mass spectrometric confirmation of C[sub 60]F[sub 60]) led to the observation of hyperfluorinated fullerenes reported here. This observation indicates cracking of the C[sub 60]-skeleton without loss of carbon atoms, i.e., isomerization to yield new carbon-cage configurations. The mass spectra of samples obtained by passing F[sub 2] gas over a fluorofullerene sample with simultaneous UV irradiation show C[sub 60]F[sub 48] to be the major constituent, with reasonably intense peaks for higher degrees of fluorination. The intensity of C[sub 60]F[sub 60][sup [center dot]+] is approximately 1.3% of the base peak. More surprisingly, the C[sub 60]F[sub 2n][sup [center dot]+] series continues well beyond n = 30. The salient C[sub 60]F[sub 2n][sup [center dot]+] peaks are real, as attested by their signal/noise ratios ([ge]2 in all cases) and the intensity of the [sup 13]C-isotope peaks (70-80% vs 66% theoretical). To our knowledge, this is the first report of substituted fullerenes with a larger number of substituents than the formal number of surface valences available. While it is certain that the peaks above C[sub 60]F[sub 60] represet transformed C[sub 60] skeletons, peaks below that point need not necessarily represent the intactmore » skeleton exclusively. 12 refs., 1 fig.« less