‘Horror vacui’ or topological in-out isomerism in perhydrogenated fullerenes: C60H60 and monoalkylated perhydrogenated fullerenes

In endohedral chemistry, one of the exciting prospects offered by the cage-like structure of fullerenes, several aspects of the calculations on in-out isomerism of perhydrogenated fullerene and their consequences went unnoticed, e.g. the topological character of the isomerism, the instability of C60F60, which was thought to revolutionize industry as an ideal lubricant, as well as the possibility of in-out isomerism in alkylated fulleranes. Molecular mechanics calculations indicate that for smaller alkyl groups the ‘in’ isomer is significantly more stable extending the possibility of endohedral fullerene chemistry. C60H60 and its derivatives can be considered as examples of a manifestation of the ancient ‘horror vacui’ concept.