Dodecahedranes structural chemistry

In the solid state, three allotropes of carbon (diamond, graphite, and fullerene Fig. 1) are well-established. Synthetic approaches to other carbon allotropes, including poly-ynes, cvclo[ ]carbons and other carbon networks have been surveyed.1 The chemistry of fullerenes, the so-called third form of carbon, and of the closely related carbon nanotubes, has been extensively detailed.2 4 The molecule C2o may be the smallest fullerene, although other structures have been suggested (Fig. 2).5 It is highly reactive and has been produced in only miniscule amounts in a mass spectrometer from a highly brominated dodecahedrane. 

Counting the isomers arising by addition to, or substitution in, a basic framework is a mathematical problem with many practical applications in chemistry. In classical organic chemistry, for example, the number of derivatives of a compound was often cited as proof or disproof of structure. Point group theory that uses concepts familiar to most chemists and is easy to apply when the number of addends/substituents is small provides a unified method for deciding, for example, the number of dihydrides C70H2 of fullerene C70, or the number of trihalo-derivatives C2oHi7FClBr of dodecahedrane. All that is needed to determine such matters is the availability of the permutation character. Ter, of the atoms in the parent molecule. 

Without question, one of the major achievements in synthesis to be published during 1982 was the synthesis of dodecahedrane by Paquette and his co-workers (7. Am. Chem. Soc., 1982, 104, 4503). This molecule (8), regarded by many scientists as the Mount Evo-est of Alicyclic Chemistry is the structurally most complex, symmetric member of the C H convex polyhedra. 

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