Entrapped Bonded Hydrogen in a Fullerene - the five atomic Cluster Sc₃CH in C₈₀

The synthesis and characterisation of the new endohedral clusterfullerene Sc₃CH@C₈₀ is reported. The encapsulation of the first hydrocarbon cluster inside a fullerene was achieved by the arc burning method in a reactive CH₄ atmosphere. The extensive characterisation by MS, HPLC, Sc-NMR, ESR, UV-Vis-NIR and Raman spectroscopy provided the experimental evidence for the caging of the five-atomic Sc₃CH cluster inside the C₈₀ cage isomer with icosahedral symmetry. The proposed new structure was confirmed by DFT calculations, which gave a closed shell and large energy gap structure. Thus a pyramidal Sc₃CH cluster and the I_h-C₈₀ cage were shown to be the most stable configuration for Sc₃CH@C₈₀ whereas alternative structures give a smaller bonding energy as well as a smaller energy gap.