On the assembling of fullerenes from cyclocarbons

A simple mechanism for fullerene formation has been postulated, based on the experimental results from mass spectrometry of cyclocarbon oxides. According to the hypothesis, cyclocarbons are only cross-bonded, without any bond being broken. In order to explain the formation of C-70 fullerene from C-18 and C-24 carbocycles, a particular C-72 isomer has been assumed as an intermediate, which decomposes into C-70 by C-2 loss. A combinatorial analysis showed that the particular C-72 isomer can be assembled from three C-24 carbocycles by formation of additional bonds between and inside the cycles, in six different ways. However, there is no single way to achieve this from four C-18 carbocycles. The results show that a more complex rearrangement must be involved in the formation of C-70 under the given conditions.