A C82 Carbon Cage Stable toward Two Different Oxidation States of Endohedral Metal Atoms

Abstract

The effect of transmutation of a metallic element encaged in C{sub 82} through EC radioactive decay was studied for the {sup 146}Gd {r_arrow} {sup 146}Eu {r_arrow} {sup 146}Sm decay series. The metallofullerene containing the EC decay progeny {sup 146}Eu was found chemically stable and eluted in a HPLC separation at a retention time which corresponded to the retention time of one of the minor isomers of Eu {at} C{sub 82}. As the oxidation state of the metal atom in Gd {at} C{sub 82} and Eu {at} C{sub 82} is known to be +3 and +2, this result suggests that the C{sub 82} cage which forms a chemically stable metallofullerene with the metal atom at the +3 oxidation state can also form a stable metallofullerene with a metal atom at the +2 oxidation state.