Metallofullerene Matryoshka

A metallofullerene version of a matryoshka—the famous Russian nesting dolls—has been made for the first time by chemists in China (J. Am. Chem. Soc., DOI: 10.1021/ja9077842). The molecule features two carbon atoms trapped inside a tetrahedral cluster of four scandium atoms, which itself is caged within an icosahedral C₈₀ fullerene. The compound, chemically identified as C₂@Sc₄@C₈₀-Ih, was synthesized, isolated, and characterized by a team led by Chun-Ying Shu and Chun-Ru Wang of Beijing’s Institute of Chemistry, along with Xin Lu of Xiamen University. The researchers prepared the metal carbide endofullerene using the Krätschmer-Huffman arc discharge method in which they applied a potential to a scandium-packed graphite rod between two electrodes in a chamber filled with inert helium gas. The group employed a battery of spectroscopic analyses to determine the molecule’s structure and used density functional theory calculations to verify its nested nature. “The six-atom cluster C₂@Sc₄ rotates freely inside the C₈₀ fullerene cage according to the spectroscopic characterizations,” Wang says. “Inspired by isolation of this molecule, we are now trying to synthesize an endohedral fullerene with C₈₀ encapsulating an even larger cluster.”