Carbide Clusterfullerene Research Articles

Fullerenes encaging metal clusters—clusterfullerenes

Clusterfullerenes represent a novel branch of endohedral fullerenes, which are characterized by a robust fullerene cage with metal clusters encaged in its hollow. Since the discovery of nitride clusterfullerenes (NCFs) in 1999, the family of clusterfullerenes has been significantly expanded within the past decade, with new members including carbide clusterfullerenes (CCFs), hydrocarbide clusterfullerenes (HCCFs), oxide clusterfullerenes (OCFs), sulfide clusterfullerenes (SCFs), and carbonitride clusterfullerenes (CNCFs). We first present the classification of clusterfullerenes and list all the clusterfullerenes reported to date. For each type of clusterfullerenes, we review in detail their synthesis, separation, intriguing molecular structures and properties. For NCFs, as the first and most important clusterfullerenes, we point out the significance of their discovery and focus on their new synthesis and separation methods as well as the new advances. Finally the potential applications of clusterfullerenes are addressed. We conclude that clusterfullerenes appear to be the fastest growing family of endohedral fullerenes up to now, and emphasize the importance of exploring new structures and chemical functionalizations of clusterfullerenes.

Metal Sulfide in a C82Fullerene Cage: A New Form of Endohedral Clusterfullerenes

The row of endohedral fullerenes is extended by a new type of sulfur-containing clusterfullerenes: the metal sulfide (M(2)S) has been stabilized within a fullerene cage for the first time. The new sulfur-containing clusterfullerenes M(2)S@C(82)-C(3v)(8) have been isolated for a variety of metals (M = Sc, Y, Dy, and Lu). The UV-vis-NIR, electrochemical, and FTIR spectroscopic characterization and extended DFT calculations point to a close similarity of the M(2)S@C(82) cage isomeric and electronic structure to that of the carbide clusterfullerenes M(2)C(2)@C(2n). The bonding in M(2)S@C(82) is studied in detail by molecular orbital analysis as well as with the use of quantum theory of atom-in-molecules (QTAIM) and electron localization function (ELF) approaches. The metal sulfide cluster formally transfers four electrons to the carbon cage, and metal-sulfur and metal-carbon cage bonds with a high degree of covalency are formed. Molecular dynamics simulations show that Sc(2)S cluster exhibits an almost free rotation around the C(3) axis of the carbon cage, resulting thus in a single line (45)Sc NMR spectrum.