Xenon cations fluoride

Xenon fluorides, 77 323-325 binary, 77 335-336 Xenon-gold cations, 77 332 Xenon halides, 77 323-325 Xenon hexafluoride, 7 7 325, 329 uses for, 7 7 336 Xenon ion lasers, 74 685 Xenon isotopes, in fission reactors, 77 375 Xenon oxide difiuoride, 77 326 Xenon oxide fluorides, 7 7 326 Xenon oxides, 77 325-326 Xenon oxide tetrafluoride, 77 326 Xenon testing, in plastics weathering, 79 584-585... 

Some monosubstituted derivatives of XeF2 can also form salts with strong Lewis acids. Unusual cations have been formed using this synthetic route. The reaction between xenon(II) fluoride orthopentafluorotellurate (FXeOTeFs) and AsFs yields a bright-yellow solid XeOTeFs+AsFe melting at 433 K. FXeOTeFs is a poorer donor of F than XeF2. 

Xenon difluoride [4, 5, 7, 8,10] is a white crystalline material obtained through the combination of fluorine and xenon m the presence of light The reagent is commercially available and possesses a relatively long shelf-life when stored cold (freezer) Xenon difluoride is very effective for small-scale fluormation of alkenes and activated nucleophilic substrates. The reactions are usually conducted between 0 °C and room temperature in chloroform or methylene chloride solutions Hydrogen fluoride catalysis is sometimes helpful Xenon difluoride reacts in a manner that usually involves some complexation between the substrate and reagent followed by the formation of radical and radical cation intermediates... 

The starting point for the synthesis of xenon compounds is the preparation of xenon difluoride, XeF2, and xenon tetrafluoride, XeF4, by heating a mixture of the elements to 400°C at 6 atm. At higher pressures, fluorination proceeds as far as xenon hexafluoride, XeFfi. All three fluorides are crystalline solids (Fig. 15.27). In the gas phase, all are molecular compounds. Solid xenon hexafluoride, however, is ionic, with a complex structure consisting of XeF< + cations bridged by F anions. 

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). 

Bridgehead iodides, namely bicyclo[n.l.l]alkyl iodides, react with xenon difluoride in dichlo-romethane at ambient temperature to form the corresponding bridgehead fluorides in high yields.1617 The process apparently involves a cationic intermediate forming as a result of heterolytic cleavage of the appropriate difluoroiodoalkane and has been named "fluorode-iodination . 

The marked propensity of the xenon fluorides towards formation of cations is related to the weakness of the Xe-F bond. We find cations such as XeF+, XeF3+, XeF/, Xe2F3+ (i.e. [F—Xe—F—Xe—F]+, with a bent Xe-F-Xe bridge) and Xe2F/ (an adduct of XeF6 with XeF/ cf. Sb2F/). 

Cationic fluoro species can be made by interaction of the binary xenon fluorides with compounds that are strong F ion acceptors such as TaF5 or PtF5. They are known for oxidation states II-VI and are of the stoichiometry Xe F . Such compounds may not be fully ionic, however, since the fluoroanions can form F-bridges to the cations. An example of this is shown in Fig. 14-2 for [XeF][RuF6]. The structure of Xe2F3 is shown in (14-I).13... 

Radical cations derived from Mrfluoro aromatic molecules were first described by Bazhin et al. > The species were made in super acid or oleum solutions and were unambiguously characterized by ESR spectroscopy. Such species have also been proposed as interm tates in the oxidative fluorination of aromatic molecules by high-valent metal fluorides such as cobalt trtfluoride, by bromine trifluoride, and by xenon difluoride. They have also been invoked in the electrochemical fluorination of aromatic molecules in the presence of F. Salts of such radical cation species were unknown prior to the synthesis of C6F6 AsF6 in these laboratories. ... 

In an effort both to clarify the nature of Xe(PtFg)2 and related compounds and to confirm the existence of the [XeF] cation, we investigated the fluoride-ion donor properties of xenon difluoride, particularly with respect to pentafluoride acceptors. A satisfactory study of these systems was made possible by the discovery that bromine pentafluoride is a good solvent for XeF2 and... 

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