Metal-carbon cluster ions

Figure 9.61 ToF mass spectrum of metal-carbon cluster ions (TiC2+ and ZrnCm+ cluster ions) using a titanium-zirconium (50 50) mixed alloy rod produced in a laser vaporization source (Nd YAG, = 532 nmj and ionization by a XeCI excimer laser (308 ). ( . M. Davis, S. J. Peppernick and A. W Castleman, J. Chem. Phys., 124, 164304(2006). Reproduced by permission of American Institute of Physics.)...

Figure 9.61 ToF mass spectrum of metal-carbon cluster ions fTiC2 and cluster ions) using...

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... 

How then is the positive charge in the (OC)9Co3C-substituted carbonium ions delocalized into the cluster substituent In our first preliminary report on this new class of carbonium ions (45), we suggested that their structure presents an especially favorable opportunity for lateral overlap of a filled er-bonding orbital of a metal-carbon bond and a vacant p orbital on an electron-deficient carbonium ion center /3 to the metal (VIII), that is believed responsible for the high... 

Most analytical studies using FT-ICR mass spectrometry, where ions have been produced inside (or just outside) the analyzer cell, have used lasers as ionization sources. Other than some very limited Cs secondary ion mass spectrometry (SIMS) studies [77], most research utilized direct laser desorption to form various organic [78] and inorganic [79] ions, including metal [80] and semiconductor [81] (including carbon) clusters. More recently matrix assisted laser desorption ionization (MALDI) has been used to form ions of high molecular weight from polymers [82] and many classes of biomolecules [83]. 

IMS-MS applications published in the literature can be grouped into two categories. The first contains studies of conformations of flexible molecules. Such flexible molecules include synthetic polymers and biopolymers such as peptides, proteins, and oligonucleotides. The studies of the second category deal with the geometry of cluster ions such as carbon clusters, semiconductor clusters, metal clusters, salt clusters, ion-ligand clusters. The major conclusions regarding structure of these systems are reviewed in Sect. 5. 

Apart from Pauling s perfect cube and from the bicapped C12 chain proposed by Ceulemans and Fowler, other structures have been assumed to be local energy minima. The metal-decorated C12 cage structures proposed by Khan on the basis of semi-empirical ZINDO-UHF calculations comprise an icosahedral C12 cluster encapsulated in a box of eight titanium atoms in a cubic or antiprismatic arrange-ment. ° A similar structure, with an extended titanium box has been proposed by the same author for TiMCn. " The possibility of obtaining three-dimensional cage carbon clusters of that size under the experimental conditions used to produce met-cars was dismissed by Cartier et The experimental results on the ion... 

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