Tungsten fullerenes

The Ba.C) N, nanotubes and fullerene-like structures have been synthesized by various laboratories in recent years. The most popular method is the plasma arc technique. The first report on the synthesis of BN nanotubes was by Zettl and coworkers (55). Since BN is an insulator, a composite anode was prepared from a tungsten rod with an empty bore in the center, which was stuffed with a pressed hexagonal BN powder. For the cathode, a water-cooled Cu rod was used. The collected gray soot contained limited amount of multi wall BN nanotubes. It is possible that in this case, the tungsten serves also as a catalyst. By perfecting this method, macroscopic amounts of double-wall BN nanotubes of a uniform diameter (2 nm)... 

Reactions of Cjq with metal carbene complexes also yield the [6,6] methano-fullerenes [392]. These adducts are probably not formed via a carbene addition, but via a formal [2-1-2] cycloaddition under formation of a metalla cyclobutane intermediate. The Fischer carbene complex [mefhyl(methoxymethylene)]pentacarbonyl chromium can be utilized to prepare l,2-mefhyl(methoxymethano)-fullerene in 20% yield [392]. A tungsten carbene complex was primarily used to initiate the formation of a polyacetylene polymer, but it was discovered that addition of to the complex-polymer-mixture improves the polymerization and dramatically increases the catalytic activity of the carbene complex [393]. can be integrated into the polymer via carbene addition. 

B. TRICARBONYL-1,2-BIS(DIPHENYLPHOSPHINO)ETHANE (FULLERENE-60)TUNGSTEN(0), W(CO)3(dppe)C6o... 

C89H24O3P2W, Tungsten(O), tricarbonyl 1,2-bis(diphenylphosphino)ethane -(fullerene-60)-, 34 109... 

The physical-chemical properties of a synthetic gallophosphate molecular sieve, the 30-A supercage cloverite , have been assessed [18]. Instead of attempting to list the burgeoning number of fullerene publications, attention is drawn to the formation and characterization of fullerene-like nanocrystals of tungsten disulfide [19,20]. Preparation, characterization and utilization of carbon nanotubes have been the subject of a number of reports from several laboratories [21-27]. 

Tungsten(VI) fluoride does not intercalate into graphite.29 but it does seem to react in some way46 with fullerenes C60/C70, but not as a fluorinating agent. 

FT-ICR, see Fourier-transform ion cyclotron resonance Fullerene[60], germanium-germanium addition, 10, 748 Fullerenes with cobalt, 7, 51 on cobalt Cp rings, 7, 73 inside metallodendrimers, 12, 401 microwave applications, 1, 334 Pd rc-complexes, 8, 348 Ru—Os complexes, 6, 830 with tungsten carbonyls, 5, 687 )2-Fullerenes, with platinum, 8, 634 Fulvalene actinide complex, synthesis, 4, 232 Fulvalene chromium carbonyls, synthesis and characteristics, 5, 264... 

Figure 14.25 Reprinted from Sloan, S., Hutchison, J.L., Tenne, R., Yishay, T.T., and Homyonferi, M. (1999) Defect and ordered tungsten oxides encapsulated (X 5S and Se) fullerene-related structures, J. Sol. St. Chem. 144, 100, Copyright 1999, with permission from Elsevier.

Palladium and tungsten composite films were prepared by simultaneous condensation of the metals and the fullerenes. The strong interaction between the metal and the fullerene led not only to charge transfer from the metal to the fullerene at the interface but also to new nanostructures in the silver and copper films. Hou et al. [113] recorded the Raman spectra of the latter as well as of a pristine fullerene film. Evidently, the metals produced new compounds with new structures, thereby reducing the symmetry of the pristine film. Unfortunately, Hou et al. did not provide information on the peak heights. It would have been interesting to note a surface enhancement of the Raman band by virtue of the metal-fullerene contact. 

With the same fullerene-method, a quantitative conversion of methionine to the corresponding sulfoxides was achieved in about 40 s, using low power, white LED illumination. The reaction time is considerably shorter when compared to the batch procedure that requires, for the same process, about 1 h illumination and the use of a 300 W tungsten halogen lamp. This may be due to the narrow channels space in a microreactor, which favors singlet oxygen diffusion, thus determining a faster reaction. 

Feldman, Y, Zak, A., Popovitz-Biro, R. and Teime, R., New reactor for production of tungsten disulfide hollow onion-like (inorganic fullerene-like) nanoparticles. Solid State Sciences, 2,2000,663-672. 

Finally, one should note that the fullerene cage concept is not just confined to carbon. Studies of boron nitride indicate that it too can form nanotubes [11,12]. Furthermore, most interestingly, Tenne and coworkers have shown that molybdenum and tungsten sulphides - long known to form layered materials also produce fullerene-related giant quasi-crystals [13,14]. 

---