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.     

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^?.     

On the synthesis of xenon(VI) fluorobismuthate(V)

The reaction between bismuth pentafluoride and excess liquid xenon hexafluoride yields a white diamagnetic solid XeF₆.BiF₅. On the basis of its Raman and infrared spectra the 1:1 compound could be formulated as XeF₅⁺BiF₆^-. The Strong fluorine-bridge interaction between cation and anion distorts the anion from O_h symmetry.     

Influence of xenon difluoride on the optical properties of fluorozirconate and fluorohafnate glasses

To study the effect of xenon difluoride as a fluorinating agent on optical properties of glasses in ZBLAN (ZrF₄–BaF₂–LaF₃–AlF₃–NaF) and HBLAN (HfF₄–BaF₂–LaF₃–AlF₃–NaF) systems, their optical transmission in the range from UV to IR was investigated. The treatment of the initial fluorides with XeF₂ was shown to lead to a broadening of the transmission region of the obtained glasses both in the UV and IR ranges. Moreover, the treatment of the batch with xenon difluoride leads to the removal of oxygen-containing impurities that absorb in the region of 2.8 μm.     

Crystal structure of monoclinic modifications of zirconium and hafnium tetrafluoride trihydrates

The monoclinic modification of ZrF₄·3H₂O, isostructural to HfF₄·3H₂O, is synthesized and structurally studied for the first time. Unlike the triclinic modification of ZrF₄·3H₂O with a dimeric structure, the synthesized compound has a polymer structure formed from infinite chains composed of ZrF₆(H₂O)₂ groups sharing F…F edges. The crystal structure of HfF₄·3H₂O, previously determined by the photo method, is refined. The refined data on the geometric characteristics of the coordination polyhedron of the Hf atom and the system of hydrogen bonds in the structure are obtained.     

Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-trifluorophthalocyaninato(2–)zirconat(IV) und -hafnat(IV); Kristallstruktur von (nBu4N)cis[Hf(F)3pc2–]

Preparation and Properties of Tetra(n-butyl)ammonium cis -Trifluorophthalocyaninato(2–)zirconate(IV) and -hafnate(IV); Crystal Structure of (ⁿBu₄N) ^cis [Hf(F)₃pc^2–] cis-Dichlorophthalocyaninato(2–)metal(IV) of zirconium and hafnium reacts with excess tetra(n-butyl)-ammoniumfluoride trihydrate to yield tetra(n-butyl)-ammonium cis-trifluorophthalocyaninato(2–)metalate(IV), (ⁿBu₄N)^cis[M(F)₃pc^2–] (M = Zr, Hf). (ⁿBu₄N)^cis[Hf(F)₃pc^2–] crystallizes in the monoclinic space group P2₁/n (# 14) with cell parameters a = 13.517(1) Å, b = 13.856(1) Å, c = 23.384(2) Å, α = 92.67(1)°, Z = 4. The Hf atom is in a ”︁square base-trigonal cap”︁”︁ polyhedron, coordinating three fluorine atoms and four isoindole nitrogen atoms (N_iso). The Hf atom is sandwiched between the (N_iso)₄ and F₃ planes (d(Hf–Ct_N) = 1.218(3) Å; d(Hf–Ct_F) = 1.229(3) Å; Ct_N/F: centre of the (N_iso)₄, respectively F₃ plane). The average Hf–N_iso and Hf–F distances are 2.298 and 1.964 Å, respectively, the average F–Hf–F angle is 84.9°. The pc^2– ligand is concavely distorted. The optical spectra show the typical metal independent π-π* transitions of the pc^2– ligand at c. 14700 and 29000 cm^–1. In the FIR/MIR spectra vibrations of the MF₃ skeleton are detected at 545, 489, 274 cm^–1 (M = Zr) and 536, 484, 263 cm^–1 (M = Hf), respectively.     

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.     

Thermal behaviour of new hydrazinium(l+) hexafluorozirconate and -hafnate

Two new hydrazinium(l+) fluorocomplexes, (N₂H₅)₂ZrF₆ and (N₂H₅)₂HfF₆ were prepared and characterized by chemical analysis, vibrational spectroscopy and X-ray powder photography. They are isostructural and the diffraction data were indexed on the basis of a monoclinic cell. Study of their thermal behaviour by TG, DTG, DTA and DSC measurements showed that they decomposed in stages. (N₂H₅)₂ZrF₆ decomposed in three steps through (NH₄)₂ZrF₅. The thermal decomposition of (N₂H₅)₂HfF₆ was more complex: in the first step (NH₄)₂HfF₆ with some N₂H₅HfH₅ was obtained, and in the second NH₄HfF₅. The intermediates were identified by chemical analysis and vibrational spectroscopy.     

Radical additions of xenon difluoride to cis- and trans-1-phenylpropenes: comparison with trichloramine and iodobenzene dichloride

We would like to report data which support a free radical pathway for reaction of xenon difluoride (XeF₂) with alkenes in organic solvent. Radical intermediates have been proposed for reaction of XeF₂ to double bonds. For example, a radical pathway was suggested for the gas phase reaction of XeF₂ to ethylene and propene [1]. Zupan speculated on a radical cation pathway for the acid catalyzed reaction of XeF₂ with alkenes but gave no experimental evidence for this mechanism [2,3]. Radical cation intermediates were demonstrated for the reaction of XeF₂ to aromatics by Filler [4]. Acid catalyzed ionic reactions to unsaturated hydrocarbons have been reviewed [5].Zupan and Pollak have shown that alkenes do not react in aprotic solvent with XeF₂ at low concentrations of alkene unless acid catalyst is present [3]. However, we observed that illumination of a dilute solution of $\text{cis-}$ or $\text{trans}$-1-phenylpropenes (I) or (II) in methylene chloride at 0° with a 270 watt sunlamp produced IIIa and IIIb in less then two hours (Table). Furthermore, at high concentration of (I) and (II), a spontaneous reaction occurred in the dark between XeF₂ and these styrenes. The reaction conditions for both of these reactions imply a radical mechanism — the latter a molecule-induced pathway.     

Xenon difluoride fluorination. IV. Photochemically initiated xenon difluoride fluorination of norbornene

Norbornene was selectively fluorinated with xenon difluoride by photochemical means. Unrearranged 2,3-difluoronorbornane isomers and acetonitrile solvent adducts were the exclusive products. This represents a novel example of controlled XeF₂ radical fluorination by light initiation.     

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.     

Spontaneous reactions of xenon,flourine and antimony pentaflouride

Mixtures of xenon and fluorine gases react spontaneously with liquid antimony pentafluoride in the dark to form solutions of XeF⁺Sb₂F^?₁₁. Dixenon cation, Xe⁺₂, is formed as a labile intermediate product and is oxidized by the fluorine to XeF⁺ cation. The rate of the overall reaction is proportional to the partial pressure of xenon and the partial pressure of fluorine. This direct combination of reagents provides a simple method for the preparation of XeF⁺Sb₂F^?₁₁.     

Über die Gasphasenstruktur von CF3NCl2 und die Darstellung von CF3NCl2F+MF6− (M = As,Sb) und CF2 = NClF+SbF6−

Gas Phase Structure of CF₃NCl₂ and Preparation of CF₃NCl₂F⁺MF₆^? (M = As, Sb) and CF₂ = NCl₂F⁺SbF₆^? The gas phase structure of CF₃NCl₂ is reported. The following skeletal parameters are derived (r_a-values, error limits are 3σ values): N? C = 1.470(6) Å, N? Cl = 1.733(3) Å, ClNCl = 111.5(4)° and ClNC = 107.6(5)°. CF₃NCl₂F⁺MF₆^? is prepared by fluorination of CF₃NCl₂ with XeF⁺MF₆^?. The same educt CF₃NCl₂ reacts with XeF⁺SbF₆^? at ?40°C to CF₂ = NClF⁺SbF₆^? under elimination of ClF.     

The reaction of XeF+MF6− (M = As,Sb) with sulfuranes; preparation of CF3(O)F2+SbF6− and (CF3)2SOXeF+SbF6−

CF₃S(O)F, (CF₃)₂SO, CF₃SF₃, (CF₃)₂SF₂, and SF₄ react in different manner with XeF⁺MF₆^? (M?As, Sb). An oxidative fluorination is observed by CF₃S(O)F forming the persulfonium salt CF₃S(O)F₂⁺SbF₆^?, whereas by (CF₃)₂SO a simple addition product containing xenon can be isolated in form of the sulfonium salt (CF₃)₂SOXeF⁺SbF₆^?. On the contrary, the Lewis-acidic character of the XeF⁺-cation predominates against (CF₃)_nSF_4?n (n = 0 ? 2) leading to the corresponding fluorosulfonium salts (CF₃)_nSF_3?n ⁺MF₆^? (M?As, Sb) and XeF₂.     

Syntheses and Molecular Structures of [(thf)4Li] [{(thf)Li}M(C4H8)3] (M = Zr,Hf) and Their Solution Behavior

The reaction of MCl₄(thf)₂ (M = Zr, Hf) with 1,4-dilitiobutane in diethyl ether at –25 °C or at 0 °C with a molar ratio of 1 : 3 yields the homoleptic “ate” complexes [(thf)₄Li] [{(thf)Li}M(C₄H₈)₃] 1 - Zr (M = Zr) and 1 - Hf (M = Hf). The crystalline compounds form ion lattices with solvent-separated [(thf)₄Li]⁺ cations and [{(thf)Li}M(C₄H₈)₃]^– anions. The NMR spectra at –20 °C show magnetic equivalence of the M–CH₂ and of the β-CH₂ groups of the butane-1,4-diide ligands on the NMR time scale. Analogous reactions of MCl₄(thf)₂ with 1,4-dilithiobutane with a molar ratio of 1 : 2 proceed unclear. However, single crystals of [Li(thf)₄] [HfCl₅(thf)] ( 2 ) can be isolated with the hafnium atom in a distorted octahedral coordination sphere of five chloro and one thf ligand. NMR spectra allow to elucidate the time-dependent degradation of 1-Hf and 1-Zr in THF and toluene at 25 °C via THF cleavage. Addition of tmeda to a solution of 1-Zr allows the isolation of intermediately formed [{(tmeda)Li}₂Zr(nBu)₂(C₄H₈)₂] ( 3 ).     

Crystal structure and NMR study of 4-amino-1,2,4-triazolium hexafluoridoniobate(V) and hexafluoridotantalate(V)

4-Amino-1,2,4-triazolium hexafluoridoniobate(V) and hexafluoridotantalate(V) (C₂H₅N₄)MF₆ (M = Nb, Ta) crystallizing in the monoclinic system (space group P2₁/n) are synthesized for the first time and their crystal structures and spectroscopic features are studied by single crystal X-ray diffraction and ¹H and ¹⁹F NMR spectroscopy. The crystal structures of isostructural (C₂H₅N₄)MF₆ compounds are formed of octahedral complex [MF₆]^– anions (M = Nb, Ta) and monoprotonated heterocyclic 4-amino-1,2,4-triazolium cations (C₂H₅N₄)⁺ organized in a three-dimensional structure via N–H···F and N–H···N hydrogen bonds. The character and types of ion motions in the fluoride sublattice of (C₂H₅N₄)MF₆ are determined in a wide temperature range.     

Bis(trifluoromethyl)fluorsulfonium(IV)-metallate(V) [1] (CF3)2SF+MF6- (M = As,Sb)

The preparation of (CF₃)₂SF⁺MF₆^- (M = As, Sb) is reported. New salts have been synthesized from the reaction of (CF₃)₂SF₂ with strong Lewis acids and CF₃SCF₃ with XeF⁺MF₆^- (M = As, Sb). They are characterised by Raman- and NMR - spectroscopy.     

Interaction of xenon diflouride with organomercury compounds

XeF₂ is shown to react with organomercury compounds, R₂Hg (R = PhCC,p-MeOC₆H₄, p-Me₂NC₆H₄, p-EtO₂CC₆H₄ and PhCH₂), with cleavage of the CHg bond. The products of the reaction are the following: Xe, RHgF (or RHgF/HgF₂ mixture; for R = benzyl RHgF undergoes fast demercurization), RF (excluding R = PhCC), R₂, and the products of radical, R·, reactions with solvents (dry CCl₄ or CHCl₃).The ease of reaction, about which one can judge from the temperature of the beginning of Xe evolution (given in brackets in °C), was found to decrease in the following sequence: R = PhCH₂ (—45) p-Me₂NC₆H₄, (—40), PhCC (—5), p-MeOC₆H₄ (5), p-EtO₂CC₆H₄ (25). This sequence indicates XeF₂ to be an electron acceptor and R₂Hg an electron donor. It follows from the reaction mixture composition that the reaction goes via free radicals. The absence of fluorinated organomercury products in the reaction mixtures may be considered as evidence that XeF₂ reacts more easily with the CHg bond than with CH or CC bonds.XeF₂ reacts also with HgX₂ (X = Cl, Br, I) under mild conditions to give X₂, HgF₂, and Xe in quantitative yields.     

Synthese und Untersuchung von Hydroxylammonium‐fluorohafnaten(IV)

Synthesis and Characterization of Hydroxylammonium Fluorohafnates(IV) Two new hydroxylammonium compounds, (NH₃OH)₂HfF₆ and (NH₃OH)₃HfF₇ were isolated from the system NH₂OH/HF/HfF₄/H₂O. The compounds were prepared by dissolving Hf‐foil in aqueous hydrofluoric acid (40 % or 20 %) followed by adding of NH₂OH in ethanolic solution. The characterization was carried out by chemical, thermal, and structural analyses. The compounds are isomorphic with the hydroxylammonium fluorozirconates. Thermal analysis of (NH₃OH)₂HfF₆ and (NH₃OH)₃HfF₇ showed that they decompose in three or two steps with HfF₄ as final product.     

Cs2Cu3MIVF12 (MIV = Zr,Hf) – Kristallstruktur und magnetische Eigenschaften

Cs₂Cu₃M^IVF₁₂ (M^IV = Zr, Hf) – Crystal Structure and Magnetic Behaviour Colourless single crystals of Cs₂Cu₃ZrF₁₂ are obtained by heating the binary fluorides in sealed Pt-tubes under dry argon (solid state reaction, T ≈? 700°C, t ≈? 7–10 d). The compound crystallizes trigonal-rhomboedrical in the space group R3 m-D (Nr. 166); lattice parameters are a = 716.61(6) pm, c = 2 046.4(2) pm, Z = 3 (Four cycle diffractometer data, AED 2). The structure is dominated by layers of corner-sharing, Jahn-Teller-distorted [CuF₆]-Octahedra, which are connected via regular [ZrF₆]-Octahedra to stackings parallel [00.1]. Cs⁺-ions are located in the spacings of the octahedra-network. From powder data Cs₂Cu₃HfF₁₂ with a = 716.32(4) pm, c = 2 048.6(2) pm is isotypic. Both compounds show antiferromagnetic behaviour already at temperatures about 200 K.