Xenon Compounds Research Articles

A stable argon compound

The noble gases have a particularly stable electronic configuration, comprising fully filled s and p valence orbitals. This makes these elements relatively non-reactive, and they exist at room temperature as monatomic gases. Pauling predicted in 1933 that the heavier noble gases, whose valence electrons are screened by core electrons and thus less strongly bound, could form stable molecules. This prediction was verified in 1962 by the preparation of xenon hexafluoroplatinate, XePtF6, the first compound to contain a noble-gas atom. Since then, a range of different compounds containing radon, xenon and krypton have been theoretically anticipated and prepared. Although the lighter noble gases neon, helium and argon are also expected to be reactive under suitable conditions, they remain the last three long-lived elements of the periodic table for which no stable compound is known. Here we report that the photolysis of hydrogen fluoride in a solid argon matrix leads to the formation of argon fluorohydride (HArF), which we have identified by probing the shift in the position of vibrational bands on isotopic substitution using infrared spectroscopy. Extensive ab initio calculations indicate that HArF is intrinsically stable, owing to significant ionic and covalent contributions to its bonding, thus confirming computational predictions that argon should form a stable hydride species with properties similar to those of the analogous xenon and krypton compounds reported before.

Novel rare gas interstitial fullerenes of C 70

The formation and characterisation of the rare gas interstitial compounds of argon, krypton and xenon with C 70 are presented. The materials were produced by hot-isostatically pressing (HIPing) powdered samples of C 70 at a temperature of 400 °C and under a surrounding rare gas pressure between 170 and 200 MPa for ~ 12 h. The materials were analysed by thermogravimetric analysis (TGA) and X-ray powder diffraction (XRD). It appears that under the HIP conditions used we were able to saturate all octahedral sites of the C 70 lattice (experimental error 5–10%), giving the rare gas stoichiometric materials Ar 1C 70, Kr 1C 70 and Xe 1C 70. The C 70 rare gas fullerenes were found to be more susceptible to loss of rare gas, compared with the corresponding C 60 materials, although the relative stabilities followed the same pattern, with heavier intercalated rare gases being lost more slowly. The argon is lost very easily (within a few days) whereas the krypton and xenon C 70 fullerenes were found to be stable at room temperature for several months, with some loss from the krypton fullerene.

Oxidative properties of xenon (II) compounds. A new, convenient synthesis of [bis(trifluoroaceteoxy)iodo]arenes, [bis(trifluoroacetoxy)iodo]perfluoroalkanes and μ-oxo-bridged aryliodoso-derivatives.

The oxidative properties of xenon bis(trifluoroacetate) relative to aryl- and perfluoroalkyliodide were studied. The interesting feature of the reaction is the formation of the iodosoesters of trifluoroacetate or their μ-oxo-derivatives.

ChemInform Abstract: Reactions of Polyhalopyridines. Part 4. Interaction of Mercaptopolychloropyridines with Fluorine‐Containing Xenon(II) Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reactions of polyhalopyridines. 9. Perfluoroalkylation of 2,3,5,6-tetrafluoro-4-mercaptopyridine with compounds of xenon containing fluorine

We showed recently that the decomposition of xenon bisperfluoroalkanecarboxylates in the presence of thiols may lead to the perfluoroalkylation of the latter [2]. This method of perfluoroalkylation is preferable for thiols with electronaccepting substituents stable in the presence of such strong oxidizing agents as compounds of xenon (II) and sensitive to the action of nucleophilic reagents. In the present report we give results of an investigation of the perfluoroalkylation of 2,3,5,6-tetra-fluoro-4-mercaptopyridine (1) using compounds of xenon containing fluorine. New derivatives of tetrafluoropyridine, viz., 2,3,5,6-tetrafluoro-4perfluoroalkylthiopyridines (IIIa-c), were obtained in 25-50% yield on carrying out the thermolytic conversion of the xenon bisperfluoroalkanecarboxylates (IIa-c) in the presence of compound (I). The xenon derivatives (IIa-c) were synthesized by the action of xenon difluoride with perfluoroalkanecarboxylic acids either previously (method A) or in situ (method B) [2]. Method A is preferred for perfluoromethylation [compound (IIia)]. Method B provides higher yields for compounds (IIIb, c).

Preparation of AmIV and AmVI in bicarbonate and carbonate solutions using xenon compounds

Xe compounds, XeF2, Na4XeO6, and XeO3, were used to oxidize AmIII in carbonate and bicarbonate aqueous solutions. XeF2 and XeO3 may be used to obtain AmIV in solutions, whereas Na4XeO6 oxidizes AmIII into AmIV+AnV+AmVI or into AmVI if present in excess. XeO3 reacts with AmIII to give AmIV only under UV irradiation.

Reaction of polyhalopyridines 4. Reaction of mercaptopolychloropyridines with fluorine-containing xenon compounds

A method has been developed for the perfluoroalkylation of mercaptopolychloropyridines by the thermolysis of xenon(II) perfluoroalkanecarboxylates, obtained by the reaction of xenon difluoride and aperfluoroalkanecarboxylic acids, in the presence of the appropriate thiol. Perfluoroalkylthio derivatives of polychloropyridines have been synthesized. The fluorosulfonyl derivatives of tetrachloropyriidne and of tetrachloropyridine N-oxide were obtained by the action of XeF2 on mercaptotetrachloropyridine dissolved in aqueous HF.

Xenon compounds - oxidezers and fluorinating agents with broad spectrum of action for advanced technologies

Recent achievements in xenon compounds synthesis and the construction of large industrial sources of gaseous xenon such as nuclear plants open the way for novel technologies in the USSR employing xenon difluoride, trioxide xenon solutions and metal hexaoxoxenonates. Several new methods of synthetic organic chemistry are proposed that superior to those being used now for these compounds. A. Direct fluorination reaction: 1. of elementorganios [1,2] 2. of nitroxyl radicals [3] 3. of N-phosphazenes and substituted benzenes [4] The synthesis of fluorides elementorganical compounds antimony, iodine, selenium, nitroxylradicals and N-phosphazenes. B. Perfluoroalkylation of thioles [5] Compounds obtained in this way are used for the synthesis of active components which find application in agrochemistry, pharmacy C.The synthesis of electroconductive polymers [6]

Exchange reactions between xenon difluoride and boron compounds — synthesis and properties of some new xenon (II) derivatives

The reactions of xenon difluoride with boron derivatives of the general formula BRX 2 (R: C 6F 5, 2,4,6F 3C 6H 2, 4FC 6H 4, C 6H 5, C 6Cl 5, 2,6-Cl 2C 6H 3; X: R, F, C1) yielded in most cases salts of the general formula [RXe] +[BF 4] −. The spectroscopic data of the new compounds and their reaction potential as oxidizers are presented. Exchange equilibria between XeF 2 and B(OR) 3 or BF 3/MOR (R: COCF 3, SO 2CF 3, aryl, alkyl) have been studied (especially by 129XeNMR spectroscopy). Several xenon compounds could be identified by NMR spectroscopy and consecutive reactions.

Structures of inorganic fluoroanions with high and low coordination numbers

The crystal structures of BrF 6 − und IF 6 − are presented. They show a remarkable difference: BrF 6 − is octahedral, IF 6 − is not. The latter is compared to the different forms of XeF 6·IF 8 − is square antiprismatical, IOF 5 − pentagonal pyramidal with apical bonded oxygen. The cations in these compounds are NO + and (CH 3) 4N +. Crystal structures of related materials are presented also. By making use of the non-bridging, highly electronegative ligand OTeF 5 a number of structures of xenon, iodine and other compounds are shown that give insight into the geometry of the central atom under conditions of low coordination.

Reactions of electrophilic addition xenon of fluorosulfates

Substitution of the fluoride on xenon difluoride with the oxygen of organic and inorganic acids [1] has been documented. Undoubtedly, these oxygen xenon compounds are stabilized with electron-withdrawing substituents can have synthetic application for the functionalization olefins, aromatic and others organic compounds. We have shown that the reaction of xenon difluoride with sulfur trioxide with the formation of two eleotrophilic reagents: FXeOSO 2F (1) and Xe(OSO 2F) 2 (2) on the ratio of starting components [2], which react at low temperatures with differents olefins to give halogenoalkylfluorosulfates. On the basis of the experimental results, we suggest the mechanism of a electrophilic addition compounds (1) and (2). The isolated yields of the product fluorosulfates are in the range of 50–85%, and structure were assigned by IR and NMR spectra.

Novel bonding situations in noble-gas chemistry

We are currently in a much better position to understand the factors underlying noble-gas compound formation. This has recently been accomplished by synthesizing over two dozen new xenon and krypton compounds in which the noble gas is bonded to organic fragments through nitrogen. The ligand groups consist of perfluoropyridines, nitriles and s-trifluorotrizine adducted to the lewis acid cations XeF+ and KrF+.The chemistry represents the first time the strongly oxidizing XeF+ and KrF+ cations have been bonded to organic moieties. The formation of HCN-XeF+AsF6- and several organic nitrile cation RCNXeF+) led to successful attempts to bond one of the best fuels known, HCN, to what is one of the strongest oxidants known, KrF+. Although the HCN-KrF+AsF6- salt is a violent detonator in the solid state at ca. -60 °C, it has been fully characterized by multi-NMR (1H, 13C, 15N and 19F) and low-temperature Raman spectroscopy. Three further examples of krypton-nitrogen bonded species in which the KrF+ cation is bonded to an organic base have also been prepared,i.e., RFCNKrF+ (RF = CF3, C2F3, n-C3F7).More recently, this chemistry has been extended to the XeOTeF5+ cation. Representative nitrile, perfluoropyridine and S- trifluorotriazine adduct cations have been prepared. The synthesis of a number of these adduct cations with Sb(OTeF3)6- as the counter ion offers the possibility of synthesizing thermally less stable XeOTeF3+ adduct cations at low temperature in low polarity solvents. This has become possible owing to the high solubility of the novel precursor salt, XeOTeF5+Sb(OTeF5)6-.Our recent discovery of the first krypton-nitrogen bonds and the previous existence of Kr-F bonded species have served to underscore the apparent anomalous non-existence of Kr-O bonds. We have recently put a considerable amount of effort into trying to synthesize the first such example of a Kr-O bond and will present the results of these findings.

Charges and bond orders in covalent xenon compounds using the structure—resonance paradigm

An empirical structure-resonance theory model for the xenon fluorides and oxyfluorides is examined, and quantitative estimates of atom charges and bond orders are derived. The results are correlated with other theoretical estimates and with related experimental properties. Realistic representations of molecular structures for the compounds containing xenon with higher oxidation states require that large numbers of octet structures, ionic resonance forms and/or expanded valence shell structures contribute to the final resonance hybrids. The representation of the effective structure—resonance theory Hamiltonian matrix by a graph allows the resulting high dimension eigenproblem to be greatly reduced using graph theoretical topological and symmetry restraints. XeF bond orders and fluorine atom charges are found to show little variation over the entire range of xenon oxidation state. The calculated xenon charges are generally much smaller but proportional to the formally assigned oxidation numbers.

Carbanion fluorination with xenon difluoride in the presence of sulfur (II) derivatives

An electrophilic fluorination reagent capable of fluorinating carbanions in moderate yield is obtained from the reaction of xenon difluoride with Sulfur II derivatives such as dimethyl sulfide. Xenon difluoride, XeF 2, has displayed much utility and versatility in the fluorination of organic substrates [1a,b]. Among the various functional groups that react with this reagent, its reaction with sulfides is especially intriguing. Both Janzen[2] and Zupan[3] have observed the fluorination of sulfides with xenon difluoride to produce S,S-difluoro derivatives. Janzen noted the possibility of an intermediate fluorosulfonium ion, (A), in his work. Moreover from the works of Bartlett[4], DesMarteau[5], and Gillespie[6] on compounds of xenon, one must also consider the involvement of an intermediate containing xenon, (B). We anticipated that either intermediate would exhibit greater stability when paired with a non-nucleophilic counter anion such as BF - 4 or OTf - and would be capable of transferring fluorine to a carbanion. The results of our study are reported here. ▪

Geometry determination for AL n systems: principles and application

The question of determining the geometry of AL n systems is approached by examining the interactions within a molecule. The consequences of assuming that LL interactions dominate the orientation of Ls around A in AL n are explored. Successful application to a wide range of AL 2, AL 3, AL 4, AL 5, AL 6, lithium oxides and xenon compounds, including excited states, radicals and charged systems is presented.

Relativistically parameterized extended hückel calculations. IX. An iterative version with applications to some xenon, thorium and uranium compounds

A charge-consistent version of the relativistic extended Hückel method REX is presented. The diagonal matrix elements are corrected for occupations of individual orbitals on the same atom using derivatives from atomic Dirac-Slater calculations and for external charges. The method is applied to systems containing the heavy atoms Xe, Th and U. For the XeF n series ( n = 2, 4, 6) the charge distributions improved compared to the non-iterative version of REX and the new results are close to non-relativistic ab initio SCF results. Bonding in the uranyl ion is discussed. The EHT-level explanations for the linear geometry by Tatsumi and Hoffmann nd by Pyykkö and Lohr are shown to be identical. The effect of secondary ligands is discussed. The role of the 6p AOs in actinoid nuclear quadrupole coupling in the actinyls is pointed out. The XPS of UF 6 is explained by different amounts of 5f character in the split components of the t 1u HOMO.

X-ray preionization of self-sustained, transverse excitation CO2 laser discharges

X rays with a mean energy of ∼50 keV produced by a flash x-ray source have been used to preionize high-pressure CO2 laser mixtures so as to obtain uniform glow discharges. The x-ray exposure measured in the active volume was 1–2 mR/pulse with a pulse duration of 100 nsec (FWHM) which permitted specific energy inputs of up to 300 J/l atm. Glow discharges were obtained for a variety of pressures and gas mixtures including some which were helium-free or in which helium was replaced by argon. Further, a realistic comparison of UV and x-ray schemes was made under sealed-off conditions. X-ray preionization appears to be advantageous and the resulting discharges are shown to tolerate oxygen (up to 2.6%) better. Additives such as xenon or organic compounds were not necessary for obtaining uniform glow discharges.

ChemInform Abstract: VOLTAMMETRIC STUDIES AND DETERMINATION OF XENON COMPOUNDS IN AQUEOUS SOLUTIONS

AbstractXe‐Verbindungen in wäßrigen Lösungen werden an glasiger Kohlenstoffelektrode irreversibel zu Xe(O) reduziert.

Voltammetric studies and determination of xenon compounds in aqueous solutions

Xenon compounds in aqueous solution at the glassy carbon electrode are irreversibly reduced to xenon(0). The observed reduction potentials vs sce for xenon compounds are: 1. Perxenate −0.49 to −0.67 V with increasing pH from 10–14; 2. Xenon trioxide −0.54 to −0.48 V with increasing pH from 7–13, and 3. Xenon difluoride at +0.19 V at pH 1.6. Platinum and mercury electrodes, are readily oxidized and are not suitable.

Chemical and physical properties of some xenon compounds

Chemical and physical properties of some xenon compounds