Specificity of carbon cages towards oxidation states of metal atoms in metallofullerenes

The effect of transmutation of the metallic element encaged in C82 through β− radioactive decay has been studied for two decay series of 155Sm→155Eu and 177Yb→177Lu, and the results were examined in combination with those reported for the decay series of 161Gd→161Tb. The metallofullerenes containing the β− decay progeny element are chemically stable if its oxidation state remains the same as that of the parent atom, namely, (+3→+3) and (+2→+2), whereas they become unstable if the oxidation state is changed like (+2→+3). This suggests that specific carbon cages can form stable metallofullerenes only with a metal atom of a given oxidation state: carbon cages for metal atoms of +2 oxidation are not the stable cage for atoms of the +3 oxidation state.