Recent development on fullerence chemistry .2. Chemical derivatization of metallofullerenes

Encapsulation of one or more metal atoms inside fullerene cages (endohedral metallofullerenes) is one of the most exciting topics in the fullerene science, since it could give rise to new species or materials with novel properties which are unexpected for hollow fullerenes. Recent important progress is marked by the successful isolation and purification of Sc@C-82, Y@C-82, La@C-82, Gd@C-82, La-2@C-80, and Sc-2@C-84 in large quantities. It is an interesting challenge to disclose how the properties of hollow fullerenes are modified upon endohedral metal-doping. Recently, we have clarified the electronic structures and properties of endohedral metallofullerenes based on the theoretical calculations and have undertaken the first exohedral functionalization of metallofullerenes with organosilicon compound which can act as a mechanistic probe to clarify the electronic and chemical character of fullerenes. These successful exohedral derivatizations of endohedral metallofullerenes should open the way to a variety of new chemical entities with novel properties, enriching the chemistry of metallofullerenes. Here we summarize our recent experimental and theoretical studies of the chemical and electronic features of monometallofullerenes and dimetallofullerenes.