Clusters carbide

Metal-carbide clusters are relevant to the fonnation of both endohedral fullerenes and carbon nanotubes [1351. There also exists a class of apparently stable metal-carbide cluster ions, = Ti, V, Cr, Zr and Hf), called... 

Duncan M A 1997 Synthesis and characterization of metal-carbide clusters in the gas phase J. duster Soi. 8 239... 

Metal carbide clusters. M. Tachikawa and E. L. Muetterties, Prog. Inorg. Chem., 1981,28,203-238 (69). 

Dyson, Paul J., Chemistry of Ruthenium-Carbide Clusters RusC(CO)i5 and... 

Jin C, Haufler RE, Hettich RL, Bashick CM, Compton RN, Puretzky AA, Dem yanenko AV, Tuinman AA (1994) Synthesis and characterization of molybdenum carbide clusters MonC4n (n = 1 to 4). Science 263 68-71... 

Niobium and rhodium cluster anions have been prepared by laser vaporization and the reactions with benzene studied by FT-ICR/MS (58). The reactions of the anions and similar cations have been compared. With few exceptions the predominant reaction of the niobium cluster anions and cations was the total dehydrogenation of benzene to form the metal carbide cluster, [Nb C6]-. The Nb19 species, both anion and cation, reacted with benzene to form the coordinated species Nb 9C6I I6p as the predominant product ion. The Nb22 ions also formed some of the addition complex but the Nb2o Nb2i, and all the other higher clusters, formed the carbide ions, Nb C6. ... 

Tachikawa, Mamoru and Muetterties, E. L., Metal Carbide Clusters. 28 203... 

The tetrahedral structure of the dianion [Fe4(CO)i3]2- has been described in Section 2.2. The reductive degradation of the carbonyl group apically bound to the Fe3 basal triangle leads to the [Fe4(CO)12C]2 carbide cluster, the molecular structure of which is shown in Figure 38.ld... 

On the more basic MgO support, low active carbide cluster species, [Ru6C(CO), 6] , are proposed as forming under CO hydrogenation conditions irrespective of the Ru precursor used [107]. 

Part of a mass spectrum for the determination of Fe and Cr contamination in boron nitride contaminated with carbon measured by LIMS is shown in Figure 6.9. The analyte ions 53Cr+ and 54Fe+ due to different masses of isobaric atomic and cluster ions are clearly separated from boron and boron carbide cluster ions as demonstrated in Figure 6.9. Cluster ion formation has been studied by laser ionization mass spectrometry (LIMS) on a boron nitride target.10... 

Besides the carbon cluster ions, carbide cluster ions are formed in different plasmas with remarkably high ion intensities. The abundance distribution of these carbide cluster ions as a function of cluster size has been observed to be very similar using the different sohd-state mass spectrometric methods, with higher intensities for cluster ions with even numbered carbon atoms than for neighbouring... 

Carbide cluster ions (MC + - M = matrix element) have been measured by investigating them directly from the solid carbides (B4C,46 SiC) or by analyzing metal oxide/graphite mixtures (for M = rare earth element,3 Si,46 Th or U36). Figure 9.60 shows the distribution of silicon carbide cluster ions (SiC +) in laser ionization mass spectrometry by the direct analysis of compact SiC in comparison to the carbide cluster ion distribution of LaC + and SrC + in spark source mass spectrometry, by investigating a metal oxide/graphite mixture. 

Unusual Compositions. Three series of compounds deserve special consideration because they have developed from laboratory curiosities into classes of their own. These are the heterometallic clusters, the carbide clusters, and the tetranuclear cu-bane clusters. 

We have shown that A) interstitial hydride formation is observed only with partial occupation of the available holes, B) occupation of the interstitial position in isolated polyhedra is not observed, and C) occupation of all the holes in a close-packed lattice cancels metal-metal interactions. Therefore, it seems that interstitial hydrogen can be tolerated only in a fraction of the total number of holes, and with the weakening of metal-metal interactions. This behavior indicates strong competition between metal-metal and metal-hydrogen bonds, which is unique for hydrogen because interstitial carbon can stabilize some unusual arrangements in carbonyl carbide clusters (29, 30). 

Chemistry of Ruthenium-Carbide Clusters Ru5C(CO)15 and Ru6C(CO)17... 

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