129Xe-Kernresonanzuntersuchungen von Xenonverbindungen. II. Xenon(II)-Derivate

¹²⁹-Xe-NMR Spectra of Xenon Compounds. II Xenon (II) Compounds The ¹²⁹Xe NMR Spectra of Xe(OSeF₅)₂, Xe(OTeF₅)₂, FXe–OSeF₅, FXe–OTeF₅, and F₅SeO–Xe–OTeF₅ have been measured and discussed. The mixed compounds FXe–OSeF₅, FXe–OSeF₅, FXe–OTeF₅, and F₅SeO–Xe–OTeF₅ exist only in equilibrium with the derivatives Xe(OSeF₅)₂, Xe(OTeF₅)₂ and XeF₂. Coupling of ¹²⁹Xe is observed with the fluorine directly bonded at the Xenon atom, with the equatorial fluorine atoms on selenium and tellurium. and with the tellurium isotop ¹²⁵Te.     

Zur Chemie des Xenons, 3. Mitt. Xenon(II)-fluorid-pentafluoro-orthotellurat als Fluoridionen-Donor: [XeOTeF5]+[AsF6]−

Interactions of Xenon(II)-fluoride-pentafluoro-orthotellurate, FXeOTeF₅, with the fluoride ion acceptors BF₃, GeF₄, PF₅, VF₅, and AsF₅ have been studied. An adduct with a molar ratio of 1∶1 is formed with AsF₅. The Laser-Raman spectrum proves it to be the salt [XeOTeF₅]+[AsF₆]^?. The pale yellow solid (M.P. 160°C) can be sublimed in vacuo at room temperature and is thermally stable up to at least 200°C in prefluorinated Monel-vessels. The fluoride ion donor strengths of FXeOTeF₅ and XeF₂ are comparable. XeF₂ however is capable of displacing FXeOTeF₅ out of [XeOTeF₅]+[AsF₆]^?. Therefore the following order of the relative fluoride ion donor strength of Xenon compounds can be given: $$XeF_4 \ll FXeOTeF_5< XeF_2< XeF_6 $$      

Zur Chemie des Xenons, 2. Mitt.: Xenon(II)-fluorid-pentafluoro-orthotellurat,FXeOTeF5 und das System XeF2−CF3COOH

Zusammenfassung Xenon(II)-fluorid-pentafluoro-orthotellurat (Sdp._0,00135°C) entsteht in quantit. Ausb. bei der Reaktion von XeF₂ mit Xe(OTeF₅)₂ im stöchiometrischen Verhältnis 11 und mit geringerer Ausbeute in der Reaktion von XeF₂ mit HOTeF₅ im Verhältnis 11. FXeOTeF₅ ist bis etwa 130°C thermisch stabil. Oberhalb dieser Temp. entsteht unter Xenonentwicklung ein Gemisch von Tellur—Sauerstoff—Fluor-Verbindungen, das noch nicht aufgetrennt werden konnte. Das Infrarot-, Laser-Raman-und¹⁹F-KMR-Spektrum von FXeOTeF₅ wurde untersucht.Im System XeF₂–CF₃COOH [mit HF, CH₃CN und (CF₃CO)₂O als Lösungsmittel] konnten Xenon(II)-fluorid-trifluoroacetat und Xenon(II)-bis(trifluoroacetat) als schwach gelblich gefärbte Festsubstanzen isoliert werden. Beide Verbindungen können ab –20°C bei thermischem oder mechanischem Schock explodieren und zerfallen bei Raumtemp. innerhalb einiger Stdn.; Xe(OOCCF₃)₂ quantitativ zu Xenon, CO₂ und Hexafluoroäthan.

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Xenon Chemistry, II: Xenon(II)-fluoride-pentafluoro-orthotellurate,FXeOTeF ₅, and the SystemXeF ₂–CF₃COOH

Xenon(II)-fluoride-pentafluoro-orthotellurate, FXeOTeF₅ (Bp.53°C; 0,001 Torr), is formed in quantitative yield in the reaction of XeF₂ with Xe(OTeF₅)₂ (molar ratio 11) and with lower yield in the reaction of XeF₂ with HOTeF₅ (molar ratio 11). FXeOTeF₅ is thermally stable up to 130°C. Above this temperature a complex mixture of tellurium—oxygen—fluorine compounds is formed, which has not yet been separated. Infrared-, laser-Raman- and¹⁹F-NMR-spectra are given.Xenon(II)-fluoride-trifluoroacetate and Xenon(II)-bis-(trifluoroacetate) are formed in the system XeF₂–CF₃COOH [with HF, CH₃CN and (CF₃CO)₂O as solvents]. Both compounds are pale yellow solids which can explode above –20°C if thermally or mechanically shocked. They decompose at room temperature within a few hours; Xe(OOCCF₃)₂ giving Xe, CO₂ and Hexafluoroethane quantitatively.

     

A Raman spectroscopic study of the XeOF4/XeF2 system and the X-ray crystal structure of α-XeOF4·XeF2

The mixed oxidation state complexes, α-XeOF₄·XeF₂ and β-XeOF₄·XeF₂, result from the interaction of XeF₂ with excess XeOF₄. The X-ray crystal structure of the more stable α-phase shows that the XeF₂ molecules are symmetrically coordinated through their fluorine ligands to the Xe(VI) atoms of the XeOF₄ molecules which are, in turn, coordinated to four XeF₂ molecules. The high-temperature phase, β-XeOF₄·XeF₂, was identified by low-temperature Raman spectroscopy in admixture with α-XeOF₄·XeF₂; however, the instability of the β-phase precluded its isolation and characterization by single-crystal X-ray diffraction. The Raman spectrum of β-XeOF₄·XeF₂ indicates that the oxygen atom of XeOF₄ interacts less strongly with the XeF₂ molecules in its crystal lattice than in α-XeOF₄·XeF₂. The ¹⁹F and ¹²⁹Xe NMR spectra of XeF₂ in liquid XeOF₄ at −35 °C indicate that any intermolecular interactions that exist between XeF₂ and XeOF₄ are weak and labile on the NMR time scale. Quantum-chemical calculations at the B3LYP and PBE1PBE levels of theory were used to obtain the gas-phase geometries and vibrational frequencies as well as the NBO bond orders, valencies, and NPA charges for the model compounds, 2XeOF₄·XeF₂, and XeOF₄·4XeF₂, which provide approximations of the local XeF₂ and XeOF₄ environments in the crystal structure of α-XeOF₄·XeF₂. The assignments of the Raman spectra (−150 °C) of α- and β-XeOF₄·XeF₂ have been aided by the calculated vibrational frequencies for the model compounds. The fluorine bridge interactions in α- and β-XeOF₄·XeF₂ are among the weakest for known compounds in which XeF₂ functions as a ligand, whereas such fluorine bridge interactions are considerably weaker in β-XeOF₄·XeF₂.     

Kernresonanzuntersuchungen an Hexafluoriden

N.M.R. Measurements on Hexafluorides ¹⁹F n.m.r. spectra of natural and ¹²⁹Xe enriched XeF₆, ²³⁸UF₆, ²³⁵UF₆, PtF₆, IrF₆, OsF₆ and AuF₆^? were measured and interpretated. The tetramerisation of XeF₆ at low temperatures can be confirmed.     

Lewis-Säuren initiierte Synthesen von Xenon-Oxo-Verbindungen — eine 129X-NMR-Studie

Lewis-Acid Initiated Syntheses of Xenon-Oxo Compounds – a ¹²⁹Xe-NMR Study The reaction of XeF₂ with B(OR)₃ yield FXeOR (R: SO₂CF₃) and Xe(OR)₂ (R: COCF3), respectively. In the second case the intermediate formation of FXeOCOCF₃ is detectable. In a solution of XeF₂ and BF3 · O(CH₃)₂ in CD₃CN the cation [FXe.NCCD3]+ can be observed. The syntheses of FXeOR (R: SO₂CF₃, SO₂C₄F₉) and Xe(OR)₂ (R:COCF₃, COC₂F₅) also succeed in the reaction of XeF₂ with the corresponding alkali metal sulfonates and carboxylates in the presence of BF₃ · O(CH₃)₂. Due to the ¹²⁹Xe-NMR spectra the mechanism of formation and the bond types of these partly new derivatives are discussed.     

The enthalpies of formation of XeF6(c), XeF4(c), XeF2(c), and PF3(g)

The energies of reaction of XeF₆(c), XeF₄(c), and XeF₂(c) with PF₃(g) were measured in a bomb calorimeter. These results were combined with the enthalpy of fluorination of PF₃(g), which was redetermined to be −(151.98 ± 0.07) kcal_th mol⁻¹, to derive (at 298.15 K) ΔH_f^o(XeF₆, c, I) = −(80.82 ± 0.53) kcal_th mol⁻¹, ΔH_f^o(XeF₄, c) = −(63.84 ± 0.21) kcal_th mol⁻¹, and ΔH_f^o(XeF₂, c) = −(38.90 ± 0.21) kcal_th mol⁻¹. The enthalpies of formation of the solid xenon fluorides were combined with reported enthalpies of sublimation to derive (at 298.15 K) ΔH_f^o(XeF₆, g) = −(66.69 ± 0.61) kcal_th mol⁻¹, ΔH_f^o(XeF₄, g) = −(49.28 ± 0.22) kcal_th mol⁻¹, and ΔH_f^o(XeF₂, g) = −(25.58 ± 0.21) kcal_th mol⁻¹. The average bond dissociation enthalpies,〈D^o〉(XeF, 298.15 K), are (29.94 ± 0.16), (31.15 ± 0.13), and (31.62 ± 0.16) kcal_th mol⁻¹ in XeF₆(g), XeF₄(g), and XeF₂(g), respectively. The enthalpy of formation of PF₃(g) was determined to be −(228.8 ± 0.3) kcal_th mol⁻¹.     

Group 6 Oxyfluoro-Anion Salts of [XeF5]+ and [Xe2F11]+: Syntheses and Structures of [XeF5][M2O2F9] (M=Mo,W), [Xe2F11][M′OF5] (M′=Cr,Mo, W), [XeF5][HF2]⋅CrOF4, and [XeF5][WOF5]⋅XeOF4

The reactions of the fluoride-ion donor, XeF₆, with the fluoride-ion acceptors, M′OF₄ (M′=Cr, Mo, W), yield [XeF₅]⁺ and [Xe₂F₁₁]⁺ salts of [M′OF₅]⁻ and [M₂O₂F₉]⁻ (M=Mo, W). Xenon hexafluoride and MOF₄ react in anhydrous hydrogen fluoride (aHF) to give equilibrium mixtures of [Xe₂F₁₁]⁺, [XeF₅]⁺, [(HF)_nF]⁻, [MOF₅]⁻, and [M₂O₂F₉]⁻ from which the title salts were crystallized. The [XeF₅][CrOF₅] and [Xe₂F₁₁][CrOF₅] salts could not be formed from mixtures of CrOF₄ and XeF₆ in aHF at low temperature (LT) owing to the low fluoride-ion affinity of CrOF₄, but yielded [XeF₅][HF₂]⋅CrOF₄ instead. In contrast, MoOF₄ and WOF₄ are sufficiently Lewis acidic to abstract F⁻ ion from [(HF)_nF]⁻ in aHF to give the [MOF₅]⁻ and [M₂O₂F₉]⁻ salts of [XeF₅]⁺ and [Xe₂F₁₁]⁺. To circumvent [(HF)_nF]⁻ formation, [Xe₂F₁₁][CrOF₅] was synthesized at LT in CF₂ClCF₂Cl solvent. The salts were characterized by LT Raman spectroscopy and LT single-crystal X-ray diffraction, which provided the first X-ray crystal structure of the [CrOF₅]⁻ anion and high-precision geometric parameters for [MOF₅]⁻ and [M₂O₂F₉]⁻. Hydrolysis of [Xe₂F₁₁][WOF₅] by water contaminant in HF solvent yielded [XeF₅][WOF₅]⋅XeOF₄. Quantum-chemical calculations were carried out for M′OF₄, [M′OF₅]⁻, [M′₂O₂F₉]⁻, {[Xe₂F₁₁][CrOF₅]}₂, [Xe₂F₁₁][MOF₅], and {[XeF₅][M₂O₂F₉]}₂ to obtain their gas-phase geometries and vibrational frequencies to aid in their vibrational mode assignments and to assess chemical bonding.     

Kationen mit Xenon—Kohlenstoff-Bindung. 4. Salze mit monosubstituiertem Phenylxenon-Kation: Darstellung,Stabilität und Reaktivität

Cations with Xenon-Carbon Bonds. 4 Salts with Monosubstituted Phenyl Xenon Cation: Preparation, Stability and Reactivity . Nucleophilic fluorine aryl substitution reactions with monosubstituted phenylboranes (X? C₆H₄)₃B and fluorophenylboranes (X? C₆H₄)_nBF_3?n (n = 1 and 2; X = m-F, p-F, m-CF₃ and p-CF₃) on XeF₂ lead to the formation of [X? C₆H₄Xe]⁺ salts with arylfluoroborate anions [(X? C₆H₄)_nBF_4?n]^? (n = 2, 1 and 0). Their thermal behaviour, their spectroscopic properties and first investigations concerning their reactivity are reported.     

On the synthesis of ammonium xenon(VI) hexafluoromanganate(IV)

The reaction between NH₄MnF₃ and xenon hexafluoride yields ammonium xenon(VI) hexafluoromanganate(IV). The persistance of the NH⁺₄ in the environment of the XeF₆, during the synthesis of the salt, can be attributed to the positive charge because XeF₆ is electrophylic and will oxidize neutral or negatively charged species but not cations. Ammonium xenon(VI) hexafluoromanganate(IV) was characterized by chemical analysis, magnetic susceptibility measurements, thermogravimetric studies and vibrational spectroscopy. The spectroscopic evidence supports the formulation NH⁺₄XeF⁺₅MnF²₆^?.     

Mass spectrometry of graphite intercalation compounds of binary fluorides of xenon,xenon oxide tetrafluoride and arsenic pentafluoride

Thermal decomposition of the intercalates of XeF₆, XeF₄, XeOF₄ and AsF₅ in graphite has been studied using a molecular beam source mass spectrometer. The product of the hydrolysis of the intercalate of XeF₆ has also been examined. The species liberated at low temperatures (T < 150°C) may be either the ones originally intercalated (XeOF₄, AsF₅) or the next lower oxidation state (XeF₄ from XeF₆, and XeF₂ from XeF₄. At higher temperatures (200-400°C) the intercalated XeF₄, XeF₂ or XeF₄ attack the graphite lattice, and evolve large quantities of xenon, and subsequently fluorocarbons and/or carbonyl fluoride. In contrast, the intercalate of AsF₅ evolves AsF₅ as the dominant gas over most of the temperature range, with a much lower degree of fluorination of the graphite lattice. The hydrolysis product of the XeF₆ intercalate was similar to the intercalate of XeF₄, but the evidence indicates that the hydrolysis proceeded well beyond XeOF₄. The extent of attack upon the graphite lattice correlates well with the oxidizing or fluorinating ability of the intercalated compound.     

Some reactions with krypton difluoride and xenon fluorides

The VF₅XeF_x (x being 2,4 and 6) system was sistematically investigated. Besides XeF_2^·.VF₅ (1) and 2XeF_6^·.VF₅ (2), new adducts XeF_6^·.VF₅ and XeF_6^·.2VF₅ were also isolated. The obtained adducts were characterized by following mass balance throughout the experiment, by Raman and IR spectroscopy, by recording the melting point - composition diagram, etc.The results of reactions in a system with some binary fluorides (e.g. TiF₄, MnF₂, CrF₃) and KrF₂ are also discussed.     

Syntheses and vibrational spectra of xenon(VI) fluorogallate,xenon(VI) fluoroaluminate and xenon(VI) fluoroindate

Liquid xenon difluoride at 140°C does not react with aluminium, gallium, and indium trifluorides, neither does liquid xenon hexafluoride at 60°C. Therefore the reactions between the corresponding hydrazinium fluorometalates (N₂H₆AlF₅, N₂H₆GaF₅ and N₂H₅InF₄) and XeF₂ and XeF₆ were carried out. N₂H₆AlF₅, N₂H₆GaF₅ and N₂H₅InF₄ react with XeF₂ at 60°C (at 25°C in the case of indium) yielding only the corresponding trifluorides, while the reaction with XeF₆ proceeds at room temperature (at - 25°C in the case of indium) yielding XeF₆.2AlF₃, XeF₆.GaF₃ and xenon(VI) fluoroindate(III) contaminated with indium trifluoride. Spectroscopic evidence suggests that these compounds are salts of the XeF⁺₅ cation squashed between polymeric anions of the type (M₂F₇)^x-_x or (MF₄)^x-_x.     

VUV spectra of the xenon fluorides

The absorption spectra of gaseous XeF₂, XeF₄, and XeF₆ have been accurately measured in the photon energy range from 6 to 35 eV with the use of the synchrotron radiation of DESY. The vibrational structure of several Rydberg transitions could be resolved. The spectra are interpreted and most of the structures could be assigned. From these data, information about the ionized species is obtained. The assignment of the first two IP's of XeF₄ is corrected.     

Tutorial review: Bohr circular orbit diagrams for some fluorine-containing molecules

Examples are provided of Bohr circular orbit diagrams to represent the electronic structures of some fluorine-containing molecules. The orbit diagrams are constructed from a 2n × n factorisation of the atomic shell-structure formula 2n², with n = 1, 2, 3, … Particular attention is given to orbit diagrams and the associated valence bond structures for the hypercoordinate molecules and ions PF₅ and NF₅, F₃⁻ and XeF₂, IF₅ and XeF₅⁺, XeF₅⁻, IF₈⁻, XeF₈²⁻, ReF₈⁻ and TaF₈³⁻, ZrF₈⁴⁻, ZrF₇³⁻, Re₂F₈²⁻, and high-spin CoF₆³⁻.Aspects of the electronic structures of D_3h-symmetry PF₅ and NF₅ are contrasted via the use of orbital valence bond considerations, and the results of STO-3G valence bond calculations are reported for these species.     

On the existence of the trifluoroxenate (II) ION,XeF3-: Comments on “the ‘base catalyzed’ fluorination of SO2 by XeF2”

Conflicting data on the existence of the trifluoroxenate (II) ion, XeF₃^-, is analyzed. In particular, lack of isotope exchange and new spectroscopic lines in XeF₂ + F^- reactions, negative ion mass spectra of xenon fluorides and the “‘Base Catalyzed’ Fluorination of SO₂ by XeF₂” are discussed.     

Synthesis of [F]xenon difluoride as a radiolabeling reagent from [F]fluoride ion in a micro-reactor and at production scale

[¹⁸F]Xenon difluoride ([¹⁸F]XeF₂), was produced by treating xenon difluoride with cyclotron-produced [¹⁸F]fluoride ion to provide a potentially useful agent for labeling novel radiotracers with fluorine-18 (t_1/2 = 109.7 min) for imaging applications with positron emission tomography. Firstly, the effects of various reaction parameters, for example, vessel material, solvent, cation and base on this process were studied at room temperature. Glass vials facilitated the reaction more readily than polypropylene vials. The reaction was less efficient in acetonitrile than in dichloromethane. Cs⁺ or K⁺ with or without the cryptand, K 2.2.2, was acceptable as counter cation. The production of [¹⁸F]XeF₂ was retarded by K₂CO₃, suggesting that generation of hydrogen fluoride in the reaction milieu promoted the incorporation of fluorine-18 into xenon difluoride. Secondly, the effect of temperature was studied using a microfluidic platform in which [¹⁸F]XeF₂ was produced in acetonitrile at elevated temperature (≥85 °C) over 94 s. These results enabled us to develop a method for obtaining [¹⁸F]XeF₂ on a production scale (up to 25 mCi) through reaction of [¹⁸F]fluoride ion with xenon difluoride in acetonitrile at 90 °C for 10 min. [¹⁸F]XeF₂ was separated from the reaction mixture by distillation at 110 °C. Furthermore, [¹⁸F]XeF₂ was shown to be reactive towards substrates, such as 1-((trimethylsilyl)oxy)cyclohexene and fluorene.     

Coordination compounds with XeF2, AsF3 and HF as ligands to metal ions: a review of reaction systematics, Raman spectra and metal, fluoro-ligand polyhedra

The reactions between Ln(AsF₆)₃ (Ln: lanthanide) and excess of XeF₂ in anhydrous HF (aHF) as a solvent yield coordination compounds [Ln(XeF₂)₃](AsF₆)₃ or LnF₃ together with Xe₂F₃AsF₆ or mixtures of all mentioned products depending on the fluorobasicity of XeF₂ and LnF₃ along the series. XeF₂ in a basic aHF is able to oxidize Pr³⁺ to Pr⁴⁺ besides Ce³⁺ to Ce⁴⁺ and Tb³⁺ to Tb⁴⁺. The tetrafluorides obtained are weaker fluorobases as XeF₂ and are immediately exchanged with XeF₂ yielding Xe₂F₃AsF₆ and LnF₄. The analogous reaction between Ln(BiF₆)₃ and XeF₂ in aHF yields [Ln(XeF₂)₃](BiF₆)₃, Ln: La, Nd. Raman spectra of the compounds [Ln(XeF₂)_n](AF₆)₃ (A: As, Bi) show that no XeF⁺ salts are formed. The interaction of XeF₂ with metal ion is covalent over the fluorine bridge. Analogous reactions of Ln(AsF₆)₃ with AsF₃ in aHF yield [Ln(AsF₃)₃](AsF₆)₃ which are stable in a dynamic vacuum at temperatures lower than 233 K. In reactions between M(AF₆)₂ (M: alkaline earth metal and Pb, A: As, Sb) and XeF₂ in aHF as a solvent, compounds of the type [M(XeF₂)_n](AF₆)₂ were synthesized. Analogous reactions with AsF₃ yield coordination compounds of the type [M(AsF₃)_n](AsF₆)₂. During the preparation of M^x(AsF₆)_x (M: metal in oxidation state x+) by the reaction between metal fluoride and excess of AsF₅ in aHF it was found that HF could also act as a ligand to the metal ions (e.g. Ca(HF)(AsF₆)₂).     

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

Xe compounds, XeF₂, Na₄XeO₆, and XeO₃, were used to oxidize Am^III in carbonate and bicarbonate aqueous solutions. XeF₂ and XeO₃ may be used to obtain Am^IV in solutions, whereas Na₄XeO₆ oxidizes Am^III into Am^IV+An^V+Am^VI or into Am^VI if present in excess. XeO³ reacts with Am^III to give Am^IV only under UV irradiation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 953–954, May, 1994.     

The “Base-catalysed” fluorination of SO2 by XeF2

The fluorination of SO₂ by XeF₂ in the presence of compounds of the type MX (M = NMe₄, Cs, K; X = F, Cl) is described.Reaction mechanisms are proposed in which the XeF₂ functions as a weak Lewis acid.