Crystal and molecular structure of a pentagonal dodecahedrane.

The successful synthesis of a pentagonal dodecahedrane molecule has been achieved. Obtained by a sequence of 20 stereochemically controlled steps beginning with the readily available cyclopentadienide anion, the 1,16-dimethyl derivative has D(3d) symmetry and unusual physical properties. The x-ray crystal structure shows that the alkyl groups cause only small distortions from pure dodecahedral symmetry.