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Synthesis and Characterization of Barium Tetrafluoridobromate(III) Ba(BrF4)2S. Ivlev[a],V. Sobolev[a], M. Hoelzel[b], A. J. Karttunen[c],T. Müller[d],I. Gerin[a], R. Ostvald[a,*],F. Kraus[d,*]* Prof. Dr. R. OstvaldFax: +7-3822-419-801E-Mail: ostvald@tpu.ru* Prof. Dr. F. KrausFax: +49 (0)6421 28-25676E-Mail: florian.kraus@chemie.uni-marburg.de[a] Tomsk Polytechnic University,Institute of Physics and TechnologyRare, Scattered and Radioactive Element Technology Department30 Lenina avenueTomsk, 634050, Russia[b] Forschungs-Neutronenquelle Heinz Maier-LeibnitzLichtenbergstra?e 185747 Garching[c] Department of ChemistryAalto UniversityFI-00076 AaltoFinland[d] Fachbereich ChemiePhilipps-Universit?t MarburgHans-Meerwein-Stra?e35032 MarburgKey words: Tetrafluoridobromate, Barium, Rietveld Refinement, IR spectra, Raman spectra, Crystal structureAbstractAlkali and alkaline earth metal tetrafluoridobromates MIBrF4, MII(BrF4)2 (MI?=?Na-Cs, MII?=?Sr, Ba) can be synthesized from the respective fluorides and BrF3. The reaction of BaF2 with liquid BrF3 under Freon-113 leads to the colorless microcrystalline powder of Ba(BrF4)2. We discuss its formation kinetics and thermodynamics. The compound crystallizes in the tetragonal space group I4 with a?=?9.65081(11), c?=?8.03453(13)??, V?=?748.32(2)??3, and Z?=?4 at 27?°C, and is isotypic to Ba(AuF4)2. The structure contains square planar BrF4? anions. The compound is shown to be stable at ambient conditions excluding moisture, and temperatures up to approximately 200?°C. Solid state computational calculations of the Raman and IR spectrum are in nice agreement with the experimentally obtained ones, which together with its powder X-ray pattern, density measurement, thermodynamics, elemental and EDXRF analysis shows the compound to be pure.IntroductionPowerful solid oxidants such as the tetrafluoridobromates(III) BrF4? of the alkali or alkaline earth metals may be interesting for a dry-chemical recycling of noble metals.[1] The accumulation of huge amounts of acidic liquid waste is prevented and additionally the usage of nitric acid or aqua regia is avoided by dry chemical workup. The tetrafluoridobromates are indefinitely stable on dry air, and thus are conveniently applicable also on industrial scale. Usually, these tetrafluoridobromates are synthesized using BrF3 and the respective alkali or alkaline earth metal fluoride by direct reaction or dissolved in anhydrous HF.[2,3] Their full oxidizing potential is unfolded only upon heating to approximately 200 ? 450?°C, depending on the counter cation and the reducing agent.[4] LiBrF4 is yet unknown,[5–7] X-ray diffraction data indicate that MBrF4 (M = Na,[8] K,[8–14] Rb[8,15,16], NO[13]) are isostructural and crystallize tetragonally. KBrF4 and KAuF4 were reported to be isostructural.[14] CsBrF4 crystallizes in the orthorhombic crystal system and is isostructural to CsAuF4.[17] Christe and coworkers reported on the synthesis and characterization of NF4BrF4,[18] NMe4BrF4,[19] and on calculated atomization energies and heats of formations of tetrafluoridobromates,[20] however no crystallographic details were given for these compounds.The first synthesis of Ba(BrF4)2 was reported by Sharpe and Emeléus by treating anhydrous barium chloride with bromine trifluoride.[5] They also reported a preparation starting from barium fluoride which gave a product of the average composition BaF2???0.9?BrF3 to BaF2???1.1?BrF3. In both cases, besides the quantitative analyses, no other further characterization had been carried out. Kiselev and co-workers reported on “The Formation of Anhydrous Sodium and Barium Fluorides by Thermal Decomposition of their Compounds with Bromine Trifluoride” and studied the thermal properties of barium tetrafluoridobromate.[21] Also, no further characterization of the Ba(BrF4)2 was given.Here we report on the synthesis and characterization of Ba(BrF4)2.Results and DiscussionSynthesis of Ba(BrF4)2A PTFE-vessel was charged with BaF2 and Freon-113. The usage of Freon-113, which was reported to be inert towards BrF3,[22] grants a proper heat exchange during the reaction and also establishes a protective layer from the moisture of the air. To prevent overboiling of the Freon-113 due to the exothermicity of the reaction, stoichiometric amounts of BrF3are gradually added. The suspension is shaken and stirred for a couple of hours to allow the heterogeneous reaction to proceed which will gradually form pure Ba(BrF4)2 as a colorless powder (eq. 1).BaF2 + 2 BrF3 → Ba(BrF4)2(1)The residual Freon-113 is then decanted and the Ba(BrF4)2is dried in vacuo (10?1?mbar). For prolonged lab storage the moisture sensitive Ba(BrF4)2 can simply be kept under Freon-113. Both chemical as well as instrumental analysis was applied for the quantitative analysis regarding Ba, Br and F (see experimental part), for spectroscopic investigations and powder X-ray and neutron diffractometry see below. The energy dispersive X-ray fluorescence analysis (EDXRF) shows a Ba/Br ratio of 1.1:2 (calculated: 1:2), which is in good agreement with the expectation. The EDXRF-spectrum is available in the supplementary information.Investigations on the formation thermodynamics of Ba(BrF4)2Equation 1 describes the formation of Ba(BrF4)2. In the hypothetical case that moisture from the air enters the system, or if moisture in BaF2 or Freon-113 were present, hydrogen fluoride would be formed by the hydrolysis of BrF3 and BrF4?. The quantitative hydrolysis of BrF3 was described by the following simplified equation 2.[23]4 BrF3 + 6 H2O → 12 HF + 2 Br2+ 3 O2(2)In the hydrolysis reaction also BrF, BrO?, and BrO3? are formed.[23] In a sample of Ba(BrF4)2 prepared by the method described above, no bromates have been detected (see below).Due to the potential presence of HF also the following chemical reactions may occur (eq. 3, 4). They may play a role in the formation of Ba(BrF4)2, present a necessity for its formation or even prevent its formation.ВаF2 + HF → ВаF2???HF(3)ВаF2???HF + 2?BrF3 → Ва(BrF4)2 + HF(4)As the thermodynamics of the Ba(BrF4)2 synthesis, its enthalpy and entropy of formation, and its heat capacity are yet unknown, the free Gibbs energy for reactions 1, 3, and 4 were calculated for the temperature range of liquid BrF3 (8.8 – 125.7 °C). This also allows to assess the influence of equations 3 and 4 on the formation of Ba(BrF4)2. The entropy and the heat capacity (see Table Tabelle) of Ba(BrF4)2were calculated according to literature procedures.[24,25].Table SEQ Tabelle \* ARABIC1. Values of the thermodynamic functions of Ba(BrF4)2.ΔG?f,298 / kJmol?1ΔH?f,298 / kJmol?1S?f,298 / J(mol K)?1C?p,298 / J(mol K)?1?2308?2280 ± 4096.4303.6Figure SEQ Figure \* ARABIC1: A plot showing the temperature dependence of the Gibbs free energies of reactions 1, 3, and 4.Indirect isothermal calorimetry (see experimental section) was employed for the experimental determination of ΔH0f of Ba(BrF4)2. ΔH0f is ?2280 ± 40 kJmol?1. The equation ΔG?T?=?ΔH?298?–?T???ΔS?298?–?ΔCp,298???T ? f(T) was used for the calculation of temperature dependent Gibbs free energies.[26] As can be seen from Figure, a potential presence of HF does not impede the formation of Ba(BrF4)2.Investigations on the formation kinetics of Ba(BrF4)2To the best of our knowledge no data on the kinetics of the synthesis of Ba(BrF4)2 are available and the time required for the complete conversion of BaF2 into Ba(BrF4)2 is yet unknown. Direct measurements of the reaction rate and its temperature dependency are very complicated due to the extreme reactivity and corrosive properties of the reaction medium. Therefore, we tried to estimate which of the parameters (temperature, particle size, stirring speed, …) influence the rate of the synthesis most.The activation energy of the reaction was determined using the transformation half-life method. The determination of the half-life was based on temperature measurements within the reaction zone starting at the moment the reagents are mixed and until the temperature increase has ceased. The transformation half-life is the time starting from the mixing of reagents until half of the temperature maximum is reached and the inversed half-life is then the reaction rate (to make this assumption plausible, we used a high excess of bromine trifluoride and kept the amount of BaF2 in each experiment constant). A direct measurement of the reaction rate constant for the interaction of BaF2 and BrF3 is quite unreliable as determinations of the BrF3 concentration are extremely difficult due to the extreme reactivity of the compounds.For the determination of the half-lifes five different initial reagent temperatures (23 °C; 33 °C; 40 °C; 45 °C; 50 °C) were used. The determined half-lifes were plotted as ln(1/τ1/2) versus 1/1000T, with τ1/2 as half-life and T as the absolute temperature (Figure 2).SEQ Figure \* ARABIC2. Figure 2. The dependence of the logarithm of the inversed half-life versus the inversed temperature.The activation energy was obtained using the Arrhenius Equation Ea = – R ln φ. R is the universal gas constant, φ is the slope. The determined activation energy Ea is 13.5 ± 0.3 kJ/mol. This value shows that the interaction is diffusion controlled. Thus, for a proper reaction the particle size of BaF2 should be as small as possible and thorough mixing is beneficial – a result that is not unexpected.Powder X-ray and neutron diffraction on Ba(BrF4)2The powder X-ray and neutron diffraction patterns measured at room temperature could be indexed in the tetragonal crystal system with the unit cell parameters a?=?9.65081(11) ?, c?=?8.03453(13)??, V?= 748.32(2)??3. The extinction conditions pointed towards I centering and the compound was found to be isotypic to Ba(AuF4)2.[27] Further details are available from Table 2, for 3 K neutron data see the supplementary information. The cell choice and the isotypicity is also confirmed by the agreement of the measured density of Ba(BrF4)2 of approximately 3.93 ± 0.02?g/cm3 and its calculated crystallographic density of 3.98?g/cm3.Table SEQ Tabelle \* ARABIC2. Crystallographic details of Ba(BrF4)2 at 300 poundBa(BrF4)2Empiric formulaBaBr2F8Color and habituscolorless powderM / (g/mol)449.1Crystal systemtetragonalSpace groupI4a / ?9.65081(11)b / ?9.65081(11)c / ?8.03453(13)V / ??748.32(2)Z4ρcalc / (Mg/m?)3.98λ / ?CuKα1, 1.54051neutron, 1.5484T / K300300Rp, wRp0.036, 0.055R(F2) (all data), wR(F2) (all data)0.092, 0.118S(all data)3.69No. of Reflections, Parameters, Constraints, Restraints5320, 50, 0, 03020, 50, 0, 02θ range measured (min, max, increment)10, 89.785, 0.0150.950, 151.9, 0.052θ range refined (min, max)10, 89.78511.8, 151.9(Δσ)max0.015Further details of the crystal structure investigations are available from the Fachinformationszentrum Karlsruhe, D-76344 Eggenstein?Leopoldshafen (Germany), , on quoting the depository number CSD-428086 (X-ray) and CSD-428087 (neutron).Figure SEQ Figure \* ARABIC3: Powder X-ray pattern of Ba(BrF4)2 at 300 K: experimental data (black crosses), calculated Rietveld profile (red), and difference profile (bottom, black). The calculated reflection positions are shown as black ticks.Figure SEQ Figure \* ARABIC4: Powder neutron pattern of Ba(BrF4)2 at 300 K: experimental data (black crosses), calculated Rietveld profile (red), and difference profile (bottom, black). The calculated reflection positions are shown as black ticks.IR and Raman spectroscopic investigationsThe relevant area of the IR and Raman spectra of Ba(BrF4)2 is shown in Figure 5. We also calculated the Raman spectrum of Ba(BrF4)2 at PBE0-DFT/SVP level of theory to facilitate the assignment of the Raman bands (Figure S4 and Table S2, supporting information). The theoretical Raman spectrum compares very well with the experimental one, as all the experimentally observed bands can be interpreted from the theoretical spectrum in a straightforward manner and the relative intensities of the bands are also reproduced well. The band assignment, carried out by analysis of the theoretical Raman spectrum and calculated normal modes, is given in Table 3. The detailed interpretation of the theoretical Raman spectrum and the full range of the IR and Raman spectra are available in the supplementary information. The spectra confirm the purity of the obtained compound and shows it to be free of moisture and HF; Br?O vibrations are also not observed.Figure SEQ Figure \* ARABIC5. Measured IR (top) and Raman (bottom) spectrum of Ba(BrF4)2.Table SEQ Tabelle \* ARABIC3. Assignment of IR and Raman bands of Ba(BrF4)2.The interpretation of the bands is straightforward and agrees well with the calculated Raman and IR intensities. The only thing "missing" in the experimental spectrum is the Br–F out-of-plane mode at about 300-320 cm?1 (the calculated intensity of this mode is about 50% of the mode at 546 cm–1).IR frequency (cm?1)Raman exp. frequency (cm?1) (rel. intensity)Raman calc. frequency (cm?1) (rel. intensity)Mode symmetry for point group D4hAssignment of the vibrational mode546 s549 (10.0)555 (10)A1gSymmetric BrF4 stretch485 vs491 (2.3)509 (4.3)EuAntisymmetric BrF4 stretch416 s450 (2.0)452 (4.7)B2gAntisymmetric BrF4 stretch273 (1.6)266 (1.3)B1gF scissoring195 (0.3)196 (0.4)B1uF rocking (+ twisting)Thermal stabilityAs evidenced by thermogravimetric analysis, Ba(BrF4)2 decomposes upon heating at approximately 198 °C into BrF3 and putational StudiesWe also investigated the vibrational properties of Ba(BrF4)2 at the DFT-PBE0/SVP level of theory (see Experimental for computational details). Full structural optimization of both the cell parameters and atomic positions within the I4 space group showed good agreement between the experiment and theory. In comparison to the neutron diffraction structure at 3 K (see supplementary information), the optimized lattice constants a and c are underestimated by 0.2 and 1.4 %, respectively. The predicted Ba–F distances are 1.1–2.6% shorter than the experimental ones, while in the case of the Br–F distances the differences vary between –1.7 and 4.5% (the Br1–F1 distance is elongated from 1.788 to 1.868 ?). As expected, a harmonic frequency calculation at the optimized geometry shows the structure to be a true local minimum. We also carried out full structural optimization of Ba(BrF4)2 without any symmetry constraints, but the optimization landed in the original minimum even if it was distorted strongly in the direction of several low-energy vibrational modes. Next, we investigated a structural distortion, where the square planar BrF4? anion was bent into other shapes such as a pyramid to see if such distortions could give rise to some of the features seen in the low-temperature neutron powder pattern, but the structural optimization of all such distortions brought the structure back to the original minimum. Finally, we calculated the full phonon dispersion relations of Ba(BrF4)2 using a direct-space supercell method (2x2x2 supercell). The phonon dispersion relations (Figure S5, supporting information) showed that there are no phonon instabilities (imaginary phonon frequencies), which could give rise to structural phase transitions.ConclusionHere we presented the reaction of BaF2 with liquid BrF3 under Freon-113 which lead to the colorless microcrystalline powder of Ba(BrF4)2. The compound crystallizes in the tetragonal space group I4 with a?=?9.65081(11), c?=?8.03453(13)??, V?=?748.32(2)??3, and Z?=?4 at 27?°C, and is isotypic to Ba(AuF4)2. The structure was elucidated using powder X-ray and neutron diffraction and it contains square planar BrF4? anions. The compound is shown to be stable at ambient conditions excluding moisture, and temperatures up to approximately 200?°C. We additionally presented its formation kinetics and thermodynamics. The calculated Raman spectrum of Ba(BrF4)2 at PBE0-DFT/SVP level of theory compares very well with the experimental one, which together with its IR spectrum, powder X-ray pattern, density measurement, elemental and EDXRF analysis shows the compound to be pure.Experimental DetailsAll operations with the tetrafluoridobromates were carried out in an atmosphere of dry and purified argon (WestfalenAG, Germany) in a sealed glove box (MBraun, Germany), so that a possible contact of the substances with moisture or air was minimized (O2 < 1 ppm, H2O < 1 ppm). BaF2 (99.5 %, Ural Plant of Chemical Reactives) was used without further purification. BrF3 was synthesized by slowly passing gaseous fluorine through liquid bromine in a nickel reactor with continuous cooling.[28,29] After completion of the reaction, the BrF3 was distilled and only the fraction with b.p.?=?125?°C was used for the experiments.Preparation of Ba(BrF4)20.39 g (2.22 mmol, 1 eq) of BaF2were placed into a PTFE tube and layered with 5 g of Freon-113. 0.61 g (4.46 mmol, 2.01 eq) of liquid BrF3were added via a dropping funnel under vigorous stirring. Freon-113 was replaced as needed. The total yield of dry Ba(BrF4)2 was 0.99 g which corresponds to 99 % yield (based on BaF2).Determination of the enthalpy of formations of Ba(BrF4)2The enthalpy of formation ofBa(BrF4)2 was determined by carrying out its synthesis in a teflon calorimeter which was preheated to a temperature close to the boiling point of Freon-113 (47.7 °C). Due to the high exothermicity of the reaction, a significant part of Freon-113 was evaporated. Therefore, provided we know the initial and final mass of the system, we may calculate the amount of evaporated Freon-113. Since its specific heat capacity is well known, it is possible to determine the amount of heat released in the course of the reaction. It is then possible to calculate the enthalpy of formation ofBa(BrF4)2using this amount of heat (equation 1).Density Measurement DetailsThe measurement of the density of Ba(BrF4)2 was carried out using a pycnometric technique. For this purpose we used a precise 5 mL pycnometer filled with Freon-113. The weighed amount of Ba(BrF4)2 (~3 g, m1) was filled in the pre-weighed empty pycnometer (m2) and covered with ~3 mL of Freon. After that the pycnometer was immersed into an ultrasonic bath in order to get finer particles and remove adsorbed gases. The Freon-113 was added up to the total volume of 5 mL, and the system was weighed again (m3). The density of Ba(BrF4)2 was calculated using the following expression:ρBaBrF42=?m15ml-(m3-m2-m1)ρfreonThe density of Ba(BrF4)2 was determined as ρ = 3.93 ± 0.02?g/cm3.Elemental AnalysisFor the elemental analysis the compound was hydrolyzed with diluted ammonia solution to dissolve it completely.[5] Barium was determined gravimetrically as barium sulfate, bromine was determined by potentiometric titration with silver nitrate using eosin as an indicator and fluorine was determined by volumetric titration with zirconyl nitrate in the presence of sodium alizarin-sulfonate.[30] BaBr2F8, found / calculated: Ba 30.5 ± 0.2 / 30.51, Br 35.6 ± 0.3 / 35.64, F 33.9 ± 0.1 / 33.85.X-ray Fluorescence AnalysisThe energy dispersive X-ray fluorescence analysis (EDXRF) was carried out on an ARL QUANT’X EDXRF spectrometer (Thermo Scientific, USA) equipped with a Peltier cooled Si(Li) detector. The measurements were done in two steps under different experimental conditions in order to obtain the primary lines for both barium and bromine. In the case of the barium line measurement a thick Cu filter and 50?kV voltage on the X-ray tube were used, while for the bromine determination we employed a Pd thick filter and 28?kV on the tube. The durations of the measurement in both cases were the same and equal to 120 seconds of lifetime. All measurements were done on air. The samples of Ba(BrF4)2 were introduced into the device in form of aqueous solutions after being hydrolyzed with distilled water in a sealed Teflon container. The sample holders were covered with thin layers of Prolene? Film (Chemplex Industries, USA).Ba/Br ratio found / calculated: 1.1:2 / 1:2. The spectrum is available in the supplementary information.Thermal InvestigationsSimultaneous thermogravimetric and differential thermal analyses were carried out with a TG/DT-analyzer SDTQ-600 (TA Instruments, USA) in graphite crucibles under argon. The heating rate was set to 10 °C/min with the sample mass ~20 mg. The mass loss was measured with the precision of 0.1 μg, the DTA sensitivity was up to 0.001 °C.Powder X-ray DiffractometryPowder X-ray diffraction patterns were obtained on a Stadi-P-Diffractometer (Stoe, Germany) using CuKα radiation, a germanium monochromator and a Mythen1K detector. The data were handled using the WINXPOW software.[31] The compounds were filled into Lindemann capillaries and flame-sealed.Powder Neutron DiffractometryNeutron powder patterns of Ba(BrF4)2 were recorded in indium sealed vanadium ampoules of 14?mm diameter and approximately 40 mm height at 27 and ?270?°C using the SPODI neutron powder diffractometer (λ?=?1.5484??) at the research reactor FRM II.[32]Structure Solution and Refinement DetailsThe powder pattern could be indexed and the reflection conditions pointed to tetragonal innenzentrierte space groups. Profile fitting and Rietveld refinement on F2 starting from atom positions of the isotypic Ba(AuF4)2 using Berar's correction was done using JANA2006 in space groupI4.[33] The choice of the space group was further supported by searching for additional symmetry using PLATON.[34] To model the peak pro?le shape, the pseudo-Voigt function was chosen. The background contribution was determined using Chebyshev polinomials with five terms. The scale factor, zero angular shift, pro?le shape parameters, and lattice parameters as well as fractional coordinates of atoms and their isotropic displacement parameters were refined. No absorption correction was applied.IR and Raman SpectroscopyIR spectra of the compounds were recorded under Ar atmosphere by using an ATR-module on a Bruker Alpha FTIR spectrometer andthe OPUS software package.[35]The Raman spectra were recorded using a Vertrex 80 MultriRam instrument equipped with a neodymium-doped YAG laser tube (λ?=?1064?nm). The samples were prepared in flame-sealed glass capillaries. The resulting data were handled with the OPUS software. Computational Details Ab initio calculations of the ground-state structure energy for Ba(BrF4)2 were carried out within the Density Functional Theory using the ABINIT code,[36,37] which is based on pseudopotential methods and planewave basis sets. The pseudopotentials for Ba, Br and F atoms were generated using the FHI code and are available for download from the ABINIT website.[38] In this work we used the Perdew-Burke-Ernzerhof GGA model to treat the exchange and the correlation.[39] For the Brillouin zone sampling a shifted Monkhorst-Pack grid of 4×4×4 k points was employed together with a cutoff energy of 80 Ha, which allowed a convergence of the total energy up to 10?3 Ha.[40] The relaxation of the atomic positions was done on constant experimental lattice parameters using a Molecular Dynamics approach in the form of the Verlet algorithm implemented in ABINIT.[41]The vibrational properties and the Raman spectrum of Ba(BrF4)2 were investigated using the CRYSTAL14 program package.[42,43] Both the atomic positions and lattice constants were fully optimized using the PBE0 hybrid density functional method.[39,44] Split-valence + polarization (SVP) level basis sets were applied for all atoms atoms (see Supporting information for additional basis set details). The reciprocal space was sampled using a 6x6x6 Monkhorst-Pack-type k-point grid. For the evaluation of the Coulomb and exchange integrals (TOLINTEG), tight tolerance factors of 8, 8, 8, 8, and 16 were used. Default optimization convergence thresholds and an extra large integration grid (XLGRID) for the density-functional part were applied in all calculations. The harmonic vibrational frequencies were obtained by using the computational scheme implemented in CRYSTAL.[45,46] The Raman intensities were obtained using the scheme implemented in CRYSTAL14.[47,48]The supporting information contains the crystallographic details and the fitted Rietveld profile of the powder neutron diffraction data obtained at 3K, the full range IR and Raman spectra, the EDXRF-Spectrum, and computational details on the CRYSTAL calculations.AcknowledgementF. K. thanks the Deutsche Forschungsgemeinschaft for his Heisenberg Professorship and Solvay Fluor for the generous donation of fluorine, Prof. Dr. R. Hoppe, and Prof. Dr. B. G. Müller for the donation of many chemicals. A. J. K. gratefully acknowledges funding from the Alfred Kordelin Foundation and Jenny and Antti Wihuri Foundation. S. I., V. S., R. O., and I. G. thank the Science Department of Tomsk Polytechnic University for an academic mobility travel grant and the Endowment Fund of TPU for providing financial support for the project. We thank Prof. A. Kornath for access to the Raman spectroscope.Literature[1] S. Ivlev, P. Woidy, F. Kraus, I. Gerin, R. Ostvald, Eur. J. Inorg. Chem.2013, 2013, 4984–4987.[2] K. O. Christe, C. J. Schack, Inorg. Chem.1970, 9, 1852–1858.[3] V. F. Sukhoverkhov, N. D. Takanova, A. A. Uskova, Zhurnal Neorganicheskoi Khimii1976, 21, 2245–2249.[4] V. N. Mitkin, Spectrochim. Acta Part B At. Spectrosc.2001, 56, 135–175.[5] A. G. Sharpe, H. J. Emeléus, J. Chem. Soc. Resumed1948, 2135–2138.[6] A. A. Woolf, H. J. Emeléus, J. Chem. Soc. Resumed1949, 2865–2871.[7] H. J. Emeléus, A. A. Woolf, J. Chem. Soc. 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Phys.2013, 139, 164102.Key TopicTetrafluoridobromates(III)TOCThe synthesis of Ba(BrF4)2 and its characterization by various methods is presented. Tetrafluoridobromates(III) may be promising materials for the dry-chemical recycling of solid noble metal wastes.TOC Graphics00 ................
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