The special nature of C28 

IPR and C28 Nature paper


The origin of this paper was a result by the Rice group which indicated that multiphoton disassociation of C60 proceeded by elimination of C2 groups and cage closure sequentially i.e. C58 > C56 > C54 etc down to C32 at which point C32 essentially exploded. This led the Rice group to suggest that this was a smallest possible fullerene. While sitting at our Lewes coffee table one Sunday afternoon playing with molecular modelling kit I wondered what possible structure of C32 might be. I produced a model and realised it was not C32 but C28 and was suddenly exhilarated because I remembered that we had an experimental run in which the C28 signal was very strong indeed. I wanted to publish our Rice/Sussex results but the request was refused so here is a later mass spectrum from Sussex with a system built with Tony Stace.


When I examined the structure of the C28 molecule I had constructed I realised that it might be very special in that it was tetrahedral and if it added say four hydrogen atoms to the for tetrahedral C corner atoms then it still retained four aromatic six-membered rings and the corner atoms would become sp3 and would be relaxed. This suggested that C28 might be a cluster super atom tetravalent analogue of the carbon atom.


Capture 2 C28 my drawing

Several years later the Rice group published a paper in which they showed that my tetravalency conjecture was correct – though it was not referenced as such – in that they observed U@C28 where the tetravalency was satisfied by an endohedral U atom.

In this paper I neglected to refer to our paper in which the structure of C70 was suggested. I just did not think about it over a year later. It was the last thing on my mind as for me it was the exhilaration of discovering the IPR and realising it essentially proved C60 was a Buckyball as well as the special nature and beautiful tetravalency of C28. This unconscious omission was assumed to be a deliberate attempt by me to gain credit for the C70 structure and used as a pretext to cause me a LOT of trouble and I only discovered this many years later by an inadvertent comment by a co-worker who had accepted this contention as true.  It is interesting to realise that you can be so affected through no fault of your own.