Carbon cages

Weaver J H, Chai Y, Kroll G H, Ohno T R, Haufler R E, Guo T, Alford J M, Conceicao J, Chibante L P F, Jain A, Palmer G and Smalley R E 1992 XPS probes of carbon caged metals Chem. Phys. Lett. 190 460... 

Mcc. Chem. Res. 25, 98—175 (Mar. 1992). A special issue on fuUerenes, small three-dimensional carbon cages such as C q, although many other C are now known as weU, including their metal derivatives. 

Magnetic properties of iron nanocrystals nested in carbon cages, which grew on the cathode deposit, have been studied by Fliura el al.[29]. Magnetization (M-H) curves showed that the coercive force. He, of... 

The final section of the volume contains three complementary review articles on carbon nanoparticles. The first by Y. Saito reviews the state of knowledge about carbon cages encapsulating metal and carbide phases. The structure of onion-like graphite particles, the spherical analog of the cylindrical carbon nanotubes, is reviewed by D. Ugarte, the dominant researcher in this area. The volume concludes with a review of metal-coated fullerenes by T. P. Martin and co-workers, who pioneered studies on this topic. 

Fig. 6), which can be used as a bridgehead scaffold for the all-carbon cage molecule Q-C6o (42), an isomer of Ih-buckminsterfullerene that is 767 kcal-mol 1 higher in energy by the calculated heats of formation (RHF/3-21G).110,291 A similar macrocyde (45, C6oH6) of easier synthetic accessibility is based on the 1,3,5-triethynylbenzene moiety. 

One particularly striking aspect of endohedral fullerene complexes is the surprising ability of the carbon cage to contain highly reactive species such as atomic nitrogen.1801 N C6o (54) has been prepared... 

Krause M, Dunsch L (2005) Gadolinium nitride Gd3N in carbon cages the influence of cluster size and bond strength. Angew. Chem. Int. Ed. Engl. 44 1557-1560. 

It is exciting to study the progression of the chemical and physical properties of these systems as a function of their size to determine at what stage (if any) these hydrocarbons begin to behave like the all-carbon cages. That is, these curved polynuclear aromatics may serve as models for the fullerenes. 

NMR and ultra-high vacuum scanning tunneling microscopy (UHV-STM) studies also demonstrate the encapsulation of the metal atoms by the carbon cage [75, 76]. 

The electrochemical properties of TNT-EMFs, M3N C2n n > 39) differ from those of the empty cage fullerenes (see Fig. 6) due to the interaction of the metal cluster with the carbon cage and because the structure of these carbon cages are generally different. As a consequence, the reductive processes are electrochemically irreversible but chemically reversible. The oxidative processes occur at lower potentials because the HOMO orbital is mainly localized on the trimetallic nitride clusters and the HOMO-LUMO gaps in solution are smaller [25,58]. The endohedral metallo-fullerenes M C2n show similar behavior but even smaller HOMO-LUMO gaps [59]. 

Chaur MN, Melin F, Ortiz AL et al (2009) Chemical, electrochemical, and structural properties of endohedral metallofullerenes. Angew Chem Int Ed 48 7514-7538 Stevenson S, Mackey MA, Stuart MA et al (2008) A distorted tetrahedral metal oxide cluster inside an icosahedral carbon cage, synthesis, isolation, and structural characterization of Sc4(p3-O)2 lh-Cgo. J Am Chem Soc 130 11844-11845... 

Another type of ligand, capable of forming multi-hapto interactions with metals, are boron and boron-carbon cage compounds of which in particular the carboranes have been used extensively in organometallic chemistry . The structures in the solid state of a few magnesacarboranes have been determined by X-ray crystallographic studies. 

Along with the other prominent carbon cage molecule found in graphite vapours is C70, containing 70 atoms of carbon. The C70 molecule has the shape of a rugby ball (Fig. 1.36). This entire family of carbon molecules is referred to as fullerenes. Other interesting species (e.g. C-,, C g, CgJ have also been identified. One of the large... 

Due to the large number of metals that can form TNT EMFs and the usually wide cage-size distribution obtained in each case, the number of different compounds that have been described and studied by electrochemistry is quite large. All of these new fascinating compounds usually show very rich redox properties and therefore have been considered promising candidates for molecular electronic applications, such as photovoltaics. The redox behavior of these compounds is influenced by the size and symmetry of the carbon cage and the nature of the metal. 

Sc3N C8o-. Influence of the Carbon Cage Symmetry Sc3N C80 is the first TNT EMF historically prepared, and numerous electrochemical studies are... 

The less-lhan-scientific ring ascribed lo the comparatively recent discovery of a third form of carbon, the fullerenes. is reminiscent ad flavors used a few years ago to describe the various kinds of quarks In the field of high-energy physics. The technical literature on fullerenes. as of early 1994. features such terms as bucky-ball. buckminstcrfullerene. buckyiube, carbon cage, dopey ball, hairy ball. Russian doll, et al.. some of which termv are synonymous others have specific connotations. Considered as an entity, fiillercne chemistry constitutes a major breakthrough in the science of physics and chemistry of materials al the molecular level. 

An extensive review of the use of density functional theory calculations on electrocyclic reactions, cycloadditions, and sigmatropic shifts has been published.3 A cycloaddition model for the transformation of graphite into the carbon cages of fullerenes is described.4... 

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