Entrapped bonded hydrogen in a fullerene:: The five-atom cluster Sc3CH in C80

The synthesis and characterisation of the new endohedral cluster fullerene Sc3CH@C-80 is reported. The encapsulation of the first hydrocarbon cluster inside a fullerene was achieved by the arc burning method in a reactive CH, atmosphere. The extensive characterisation by mass spectrometry (MS), high- pressure liquid chromatography (HPLC), Sc-45 NMR, electron spin resonance (ESR), UV/Vis-NIR and Roman spectroscopy provided the experimental evidence for the caging of the five-atom Sc3CH cluster inside the C, cage isomer with icosahedral symmetry. The proposed new structure was confirmed by DFT calculations, which gave a closed shelf and large energy gap structure. Thus a pyramidal Sc3CH cluster and the l(h)-C-80 cage were shown to be the most stable configuration for Sc3CH@C-80 whereas alternative structures give a smaller bonding energy as well as a smaller energy gap.