PENTAMETHYLCYCLOPENTADIENE ADDUCTS OF [60]-FULLERENE AND [70]-FULLERENE

Pentamethylcyclopentadiene reacts with [60]- and [70]-fullerene to form Diels-Alder monoadducts, characterised by H-1 and C-13 NMR spectroscopy, in which the methyl group attached to the single carbon bridge points away from the cage. Cycloaddition to [70]fullerene takes place across the 1,9-bond adjacent to the pentagonal cap. The pentamethyl,adducts are less prone to undergo the retro Diels-Alder reaction than their non-methylated counterparts. The H-1 NMR spectra provide further confirmation that [70]fullerene is less electron withdrawing than [60]fullerene.