FULLERENES WITH METALS INSIDE

Fullerenes with a single lanthanum atom trapped on the inside of the carbon cage were produced by laser vaporization of a lanthanum oxide/graphite composite rod in a flow of argon gas at 1200-degrees-C. When sublimed with C60 and C70, they formed an air-stable film containing principally LaC60, LaC70, LaC74, and LaC82. When dissolved in toluene and exposed to air, LaC82 was found to be uniquely stable. Evidence was also obtained for coalescence reactions between these fullerenes at high temperatures to form larger cages with as many as three lanthanum atoms inside. Indications have also been obtained for the successful production of KC60, C59B, and KC59B where the boron has substituted for a carbon in the soccerball cage. The use of the @ symbol is advocated for specifying such complex fullerenes as (K @ C59B).