Synthesis and Characterization of Barium Tetrafluoridobromate(III) Ba(BrF4)2

S. 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.dehttp://www.uni-marburg.de/fb15/fachgebiete/anorganik

[a] Tomsk Polytechnic University,Institute of Physics and TechnologyRare, Scattered and Radioactive Element Technology Department30 Lenina avenueTomsk, 634050, Russia[b] Forschungs-Neutronenquelle Heinz Maier-LeibnitzLichtenbergstraße 185747 Garching[c] Department of ChemistryAalto UniversityFI-00076 AaltoFinland[d] Fachbereich ChemiePhilipps-Universität MarburgHans-Meerwein-Straße35032 Marburg

Key words: Tetrafluoridobromate, Barium, Rietveld Refinement, IR spectra, Raman spectra, Crystal structure

Abstract

Alkali 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 forma-

tion kinetics and thermodynamics. The compound crystallizes in the tetragonal space group I 4̄ with

a = 9.65081(11), c = 8.03453(13) Å, V = 748.32(2) Å3, 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 experi-

mentally obtained ones, which together with its powder X-ray pattern, density measurement, ther-

modynamics, elemental and EDXRF analysis shows the compound to be pure.

Introduction

Powerful 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 Discussion

Synthesis of Ba(BrF4)2

A 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)2

Equation 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 1. Values of the thermodynamic functions of Ba(BrF4)2.

ΔGºf,298 / kJmol−1 ΔHºf,298 / kJmol−1 Sºf,298 / J(mol K)−1 Cºp,298 / J(mol K)−1

−2308 −2280 ± 40 96.4 303.6

Indirect isothermal calorimetry (see experimental section) was employed for the experimental determination of ΔH0

f

of Ba(BrF4)2. ΔH0

f is −2280 ± 40 kJmol−1. The equation

ΔGºT = ΔHº298 – T ∙ ΔSº298 – 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)2

To the best of our knowledge no data on the kinetics of the synthesis of Ba(BrF4)2 are available and

Figure 1: A plot showing the temperature dependence of the Gibbs free energies of reactions 1, 3, and 4.

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).

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

3.05 3.1 3.15 3.2 3.25 3.3 3.35 3.4-3.2

-3.1

-3

-2.9

-2.8

-2.7

-2.6

1000/T

ln(1/τ)

. Figure 2. The dependence of the logarithm of the inversed half-life versus the inversed temperature.

unexpected.

Powder X-ray and neutron diffraction on Ba(BrF4)2

The 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) Å, c = 8.03453(13) Å,

V = 748.32(2) Å3. 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 2. Crystallographic details of Ba(BrF4)2 at 300 K.

Compound Ba(BrF4)2

Empiric formula BaBr2F8

Color and habitus colorless powder

M / (g/mol) 449.1

Crystal system tetragonal

Space group I 4̄a / Å 9.65081(11)

b / Å 9.65081(11)

c / Å 8.03453(13)

V / ų 748.32(2)

Z 4

ρcalc / (Mg/m³) 3.98

λ / Å CuKα1, 1.54051 neutron, 1.5484

T / K 300 300

Rp, wRp 0.036, 0.055

R(F2) (all data), wR(F2) (all data) 0.092, 0.118

S(all data) 3.69

No. of Reflections, Parameters, Constraints, Restraints 5320, 50, 0, 0 3020, 50, 0, 0

2θ range measured (min, max, increment) 10, 89.785, 0.015 0.950, 151.9, 0.05

2θ range refined (min, max) 10, 89.785 11.8, 151.9

(Δσ)max 0.015

Further details of the crystal structure investigations are available from the Fachinformationszentrum Karlsruhe, D-76344 Eggenstein−Leopoldshafen (Germany), http://www.fiz−karlsruhe.de/icsd.html, on quoting the depository num-ber CSD-428086 (X-ray) and CSD-428087 (neutron).

IR and Raman spectroscopic investigations

Figure 3: 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 4: 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.

The 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.

Table 3. 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 D4h

Assignment of the vibrational mode

546 s 549 (10.0) 555 (10) A1g Symmetric BrF4 stretch485 vs 491 (2.3) 509 (4.3) Eu Antisymmetric BrF4 stretch416 s 450 (2.0) 452 (4.7) B2g Antisymmetric BrF4 stretch

273 (1.6) 266 (1.3) B1g F scissoring195 (0.3) 196 (0.4) B1u F rocking (+ twisting)

Figure

. Measured IR (top) and Raman (bottom)

Thermal stability

As evidenced by thermogravimetric analysis, Ba(BrF4)2 decomposes upon heating at approximately

198 °C into BrF3 and BaF2.

Computational Studies

We 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 I 4̄ 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 Å). 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.

Conclusion

Here we presented the reaction of BaF2 with liquid BrF3 under Freon-113 which lead to the color-

less microcrystalline powder of Ba(BrF4)2. The compound crystallizes in the tetragonal space group

I 4̄ with a = 9.65081(11), c = 8.03453(13) Å, V = 748.32(2) Å3, 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 con-

tains square planar BrF4− anions. The compound is shown to be stable at ambient conditions exclud-

ing 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 Details

All 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)2

0.39 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)2

The 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 Details

The 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:

ρBa( BrF4 )2=  

m1

5ml−(m3−m2−m1)

ρfreon

The density of Ba(BrF4)2 was determined as ρ = 3.93 ± 0.02 g/cm3.

Elemental Analysis

For 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 Analysis

The 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 Investigations

Simultaneous 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 Diffractometry

Powder 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 Diffractometry

Neutron 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 Å) at the research reactor FRM II.[32]

Structure Solution and Refinement Details

The powder pattern could be indexed and the reflection conditions pointed to tetragonal innenzen-

trierte 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 groupI 4̄.[33]

The choice of the space group was further supported by searching for additional symmetry using

PLATON.[34] To model the peak profile shape, the pseudo-Voigt function was chosen. The back-

ground contribution was determined using Chebyshev polinomials with five terms. The scale factor,

zero angular shift, profile 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 Spectroscopy

IR 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.

Acknowledgement

F. 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.

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164102.

Key Topic

Tetrafluoridobromates(III)

TOC

The 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 Graphics