Xenon cations from

The ionic nature of these species was deduced from the very beginning on the basis of the identification of the anionic counter ion, [BFJ ", in the complex XeF6 BF3 116), but the first characterization of the [XeF5]+ cation itself was only attempted later 170). The full characterization of [Xe2Fn]+ was even more recent120). The two hexavalent xenon cations are related in much the same way as [XeF]+ and [Xe2F3] + in xenon(H) complexes i.e. the simpler cations are joined by a fluorine bridge. 

In the complex xenon functions as a n-donor toward Au2+. This is reflected in the calculated charge distribution within the cation, where the main part of the positive charge resides on the xenon atoms. Relativity plays a large role in stabilizing this and other predicted Au—Xe compounds about half of the Au—Xe bonding energy comes from relativistic effects.1993... 

Heats of formation for a complete set of Group VILA fluorides are unavailable, but a set of xenon fluoride cations, isoelectronic with iodine fluorides, exhibits the alternating pattern expected for odd- and even-electron molecules. The original energy-level diagram for stepwise fluorine dissociation is shown in Fig. 5. The tabulated values were derived from the ionization energies of XeF and the threshold values for XeFJ — XeF, - + F, where n is even (27), together with heats of formation obtained by reaction calorimetry (137). 

Barber et al. introduced FAB in 1981. In this technique, bombardment of a liquid target surface by a beam of fast atoms such as xenon or argon, causes the continuous desorption of ions that are characteristic of the liquid. In a typical FAB spectrum, the analyte ion is usually formed as protonated or cationized ions in positive FAB, and deprotonated ions in negative FAB mode. A few fragmented ions may also be formed. The spectrum usually contains peaks from the matrix, such as protonated matrix clusters of glycerol if it is used as the matrix solvent. FAB utilizes a liquid matrix such as glycerol. The matrix is used to enhance sensitivity and ion current stability. 

The halogen pentafluorides and the [XeF5]+ cation have a square pyramidal configuration and any weak secondary bonds are found below the base of the pyramid and situated to avoid the axial, lone pair position. These contacts are much more significant for the xenon compounds than for the interhalogens, where they are so weak as to be virtually indistinguishable from normal intermolecular contacts, as seen in the structure of IF5.40... 

This big influence of temperature on the equilibrium is a consequence of the large change in translational entropy in going from reactants to products [15]. Agf+iv) is also able to oxidize perfluoroolefins such as perfluoropropene the ionization potential of which is much lower (7= 10.62 eV) [29] than those of xenon or oxygen. The observed formation of perfluoropropane (quantitatively) is in accord with the cation being attacked by F, followed by a second one-electron oxidation and F attack. The hierarchy of powerful oxidizers could be written as follows (see also Sections 4.2.2.5 and 4.2.2.6). 

Additional acid ensures that Ag(II) remains in solution as cationic species (i.e. AgF2, which is insoluble in aHF, is not precipitated) and the xenon oxidation continues. Removal of aHF from a solution where additional fluoro acid was not provided for the neutralization of XeF2 gave a mixture of AgF2, Xe2F3AsF6 and [Ag(XeF2)2]AsF6 [39],... 

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