Synthesis and low temperature fluorination of the alkaline-earth palladates Ba2−xSrxPdO3 (x = 0–2)

Since the discovery of superconductivity in Sr₂CuO₂F_2+δ there has been an increased interest in ternary oxide-fluorides. Sr₂CuO₂F_2+δ is prepared via low temperature (T = 220 °C) reaction routes. Low temperature fluorination induces an interesting structural rearrangement in the parent compound Sr₂CuO₃, which is a one-dimensional material containing linear chains of vertex sharing CuO₄ squares along the crystallographic b axis. Upon fluorination, one oxide is substituted by two fluorides and Cu²⁺ becomes octahedrally coordinated by four oxides and two fluorides. The fluorinated compound Sr₂CuO₂F_2+δ displays the T-type structure (La₂CuO₄). Insertion of excess fluorine, δ, also takes place and this fluorine occupies interstitial sites in the T structure. Although the starting material Ca₂CuO₃ is isostructural to Sr₂CuO₃, Ca₂CuO₂F_2+δ displays the T′ (Nd₂CuO₄) structure due to the smaller radius of Ca²⁺ compared to that of Sr²⁺.

The alkaline-earth palladates with the general formula A₂PdO₃ (A = Ba, Sr) are isostructural with the A₂CuO₃(A = Ca, Sr) materials. We prepared the Ba_2−xSr_xPdO₃ (x = 0–2) series and performed low temperature fluorination, which led to the synthesis of the series Ba_2−xSr_xPdO₂F_2+δ (0 ≤ x ≤ 1.5). All the compounds in the Ba_2−xSr_xPdO₂F_2+δ series show T′ structure (Ca₂CuO₂F_2+δ). Similarities and differences with Sr₂CuO₂F_2+δ and Ca₂CuO₂F_2+δ will be discussed.     

Unusual impurity effect on room-temperature ferromagnet Sr3YCo4O10.56

We have prepared polycrystalline samples of Sr₃YCo₄O_10.56, Sr_2.4Ca_0.6YCo₄O_10.54, and Sr₃YCo_3.76Mn_0.24O_10.59, and found that these materials show unusual impurity effects on their transport and magnetic properties. A tiny amount of impurities such as Mn or Ca suppresses room-temperature ferromagnetism of Sr₃YCo₄O_10.56. With the suppression, their resistivities and thermopowers are also dramatically changed. We propose that the unusual impurity effects are caused by the suppression of orbital ordering.     

Sub-solidus phase equilibria in CeO2–SrO system

In this communication, we report on the synthesis and characterization of a series of compounds with the general composition Ce_1−xSr_xO_2−x (0.0≤x≤1.0), to establish a detailed phase relation in the CeO₂–SrO system. The X-ray diffraction (XRD) pattern of the each product was refined to determine the solid solubility and the homogeneity range. The solid solubility limit of SrO in CeO₂ lattice, under the slow cooled conditions, is represented as Ce_0.91Sr_0.09O_1.91 (i.e. 9 mol% of SrO). A careful delineation of the phase boundary revealed that the stoichiometric SrCeO₃, in fact, contains a little amount of CeO₂ also. The mono-phasic compound could be obtained at the nominal composition Sr_0.55Ce_0.45O_1.45. The nominal composition Sr₂CeO₄, under the heat treatment used in the present investigation, was a bi-phasic mixture of SrCeO₃ and SrO. No new ordered phases were obtained in this system.     

Standard enthalpies of formation of Sr2CuO3 and Ca2CuO3

The enthalpies of reactions between alkaline-earth cuprates M₂CuO₃ (M = Ca, Sr) and hydrochloric acid were measured in a hermetic swinging calorimeter at 298.15 K. The M₂CuO₃ samples were prepared by solid-phase synthesis from calcium or strontium carbonate and copper oxide and characterized by X-ray powder diffraction, EDX and wet analysis. The standard enthalpies of formation obtained for the cuprates, −1431 ± 4 kJ mol⁻¹ for Ca₂CuO₃ and −1374 ± 3 kJ mol⁻¹ for Sr₂CuO₃, are discussed and compared with previous experimental and assessed values.     

Possible spin-Peierls transition in La2RuO5

The semiconductor–semiconductor transition of La₂RuO₅ is studied by means of augmented spherical wave (ASW) electronic structure calculations as based on density functional theory and the local density approximation. This transition has lately been reported to lead to orbital ordering and a quenching of the local spin magnetic moment. Our results give strong hints for a different orbital ordering scenario than the one previously proposed. In our type of ordering the local S = 1 moment at the Ru sites is preserved in the low-temperature phase. The unusual magnetic behaviour is interpreted by the formation of spin ladders resulting from the structural transformations occurring at the transition. The spin ladders are characterized by antiferromagnetic coupling along the rungs. The loss of the total spin moment is attributed to a spin-Peierls transition.     

The electrolyte NRTL model and speciation approach as applied to multicomponent aqueous solutions of H2SO4, Fe2(SO4)3, MgSO4 and Al2(SO4)3 at 230–270 °C

This work presents chemical modeling of solubilities of metal sulfates in aqueous solutions of sulfuric acid at high temperatures. Calculations were compared with experimental solubility measurements of hematite (Fe₂O₃) in aqueous ternary and quaternary systems of H₂SO₄, MgSO₄ and Al₂(SO₄)₃ at high temperatures. A hybrid model of ion-association and electrolyte non-random two liquid (ENRTL) theory was employed to fit solubility data in three ternary systems H₂SO₄–MgSO₄–H₂O, H₂SO₄–Al₂(SO₄)₃–H₂O at 235–270 °C and H₂SO₄–Fe₂(SO₄)₃–H₂O at 150–270 °C. Employing the Aspen Plus™ property program, the electrolyte NRTL local composition model was used for calculating activity coefficients of the ions Al³⁺, Mg²⁺ Fe³⁺ and SO₄²⁻, HSO₄⁻, OH⁻, H₃O⁺, respectively, as well as molecular species. The solid phases were hydronium alunite (H₃O)Al₃(SO₄)₂(OH)₆, hematite Fe₂O₃ and magnesium sulfate monohydrate (MgSO₄)·H₂O which were employed as constraint precipitation solids in calculating the metal sulfate solubilities. A correlation for the equilibrium constants of the association reactions of complex species versus temperature was implemented. Based on the maximum-likelihood principle, the binary interaction energy parameters for the ionic species as well as the coefficients for equilibrium constants of the reactions were obtained simultaneously using the solubility data of the ternary systems. Following that, the solubilities of metal sulfates in the quaternary systems H₂SO₄–Fe₂(SO₄)₃–MgSO₄–H₂O, H₂SO₄–Fe₂(SO₄)₃–Al₂(SO₄)₃–H₂O at 250 °C and H₂SO₄–Al₂(SO₄)₃–MgSO₄–H₂O at 230–270 °C were predicted. The calculated results were in excellent agreement with the experimental data.     

Catalytic decomposition of H2O2 on Co3O4 doped with MgO and V2O5

The effects of doping of Co₃O₄with MgO (0.4–6 mol%) and V₂O₅ (0.20–0.75 mol%) on its surface and catalytic properties were investigated using nitrogen adsorption at −196°C and decomposition of H₂O₂ at 30–50°C. Pure and doped samples were prepared by thermal decomposition in air at 500–900°C, of pure basic cobalt carbonate and basic carbonate treated with different proportions of magnesium nitrate and ammonium vanadate. The results revealed that, V₂O₅ doping followed by precalcination at 500–900°C did not much modify the specific surface area of the treated Co₃O₄ solid. Treatment of Co₃O₄ with MgO at 500–900°C resulted in a significant increase in the specific surface area of cobaltic oxide. The catalytic activity in H₂O₂ decomposition, of Co₃O₄ was found to suffer a considerable increase by treatment with MgO. The maximum increase in the catalytic reaction rate constant (k) measured at 40°C on Co₃O₄ due to doping with 3 mol% MgO attained 218, 590 and 275% for the catalysts precalcined at 500, 700 and 900°C, respectively. V₂O₅-doping of Co₃O₄ brought about a significant progressive decrease in its catalytic activity. The maximum decrease in the reaction rate constant measured at 40°C over the 0.75 mol% V₂O₅-doped Co₃O₄ solid attained 68 and 93% for the catalyst samples precalcined at 500 and 900°C, respectively. The doping process did not modify the activation energy of the catalyzed reaction but much modified the concentration of catalytically active constituents without changing their energetic nature. MgO-doping increased the concentration of CO³⁺–CO²⁺ ion pairs and created Mg²⁺–CO³⁺ ion pairs increasing thus the number of active constituents involved in the catalytic decomposition of H₂O₂. V₂O₅-doping exerted an opposite effect via decreasing the number of CO³⁺–CO²⁺ ion pairs besides the possible formation of cobalt vanadate.     

Synthesis and structural behavior of the P-functional organotin chlorides [Ph2P(CH2)3]2SnCl2, Ph2P(CH2)3SnCl2Me, and Ph2P(CH2)nSnCl3 (n=2, 3)

The P-functional organotin dichloride [Ph₂P(CH₂)₃]₂SnCl₂ (3) is synthesized by reaction of Ph₂P(CH₂)₃MgCl with SnCl₄ independently of the molar ratio of the starting compounds. The corresponding organotin trichlorides Ph₂P(CH₂)_nSnCl₂R (4: n=2, R=Cl; 5: n=3, R=Cl; 6: n=3, R=Me) are formed in a cleavage reaction of Ph₂P(CH₂)_nSnCy₃ (n=2, 3) with SnCl₄ or MeSnCl₃, respectively. The main features of the crystal structures of 3–6 are both intra- and intermolecular PSn coordinations and the existence of intermolecular Sn---ClSn bridges. For further characterization of the title compounds, the adducts 4(Ph₃PO)₂ (7) and 5(Ph₃PO) (8), as well as the P-oxides and P-sulfides of 3–6 (9–15), are synthesized. The results of crystal structure analyses of 7, 11, 12, and 14 are reported. The structures of 9–15 are characterized by intramolecular P=XSn interactions (X=O, S). A first insight into the structural behavior of the compounds 3–15 in solution is discussed on the basis of multinuclear NMR data.     

Synthesis of spherical nanoparticles of Cu2L2O5 (L=Ho, Er) from W/O microemulsions

Nanoparticles of Cu₂L₂O₅ (L=Ho, Er) (15–25 nm in size) were synthesised by the intermediate use of W/O microemulsions. In this process the aqueous cores of water/cetyltrimethylammonium bromide/n-octane/1-butanol microemulsions were used as microreactors for the precipitation of Cu₂Ho₂(CO₃)₄(OH)₂ (25–30 nm) and Cu₂Er₂(CO₃)₄(OH)₂ (10–40 nm) as precursors. These mixed salts were separated and further decomposed to the corresponding mixed oxides at 900°C for 16 h. All solids were characterised by scanning and transmission electron microscopy, IR, XRPD, ICP-OES, TGA, XPS measurements and elemental analyses.     

Synthesis of titanium(IV) complexes that contain the Bis(silylamide) ligand of the type [1,8-C10H6(NR)2], and alkene polymerization catalyzed by [1,8-C10H6(NR)2]TiCl2-cocatalyst system

[1,8-C₁₀H₆(NR)₂]TiCl₂ (3; R=SiMe₃, SiⁱBuMe₂, SiⁱPr₃) complexes have been prepared from dilithio salts [1,8-C₁₀H₆(NR)₂]Li₂ (2) and TiCl₄ in diethyl ether in moderate yields (60–63%). These complexes showed significant catalytic activities for ethylene polymerization and for ethylene/1-hexene copolymerization in the presence of methylaluminoxane (MAO), methyl isobutyl aluminoxane (MMAO), AlⁱBu₃– or AlEt₃–Ph₃CB(C₆F₅)₄ as a cocatalyst. The catalytic activities performed in heptane (cocatalyst MMAO) were higher than those carried out in toluene (cocatalyst MAO): 709 kg-PE/mol-Ti·h could be attained for ethylene polymerization by using [1,8-C₁₀H₆(NSiⁱBuMe₂)₂]TiCl₂–MMAO catalyst system.     

Synthesis and molecular structure of Ba5(μ5-OH)[μ3-OCH(CF3)2]4[μ2-OCH(CF3)2]4 [OCH(CF3)2](THF)4(H2O)·THF: a source of barium fluoride

The reaction between metallic barium and fluoroisopropanol or alcoholysis of [Ba(OPrⁱ)₂] produces a pentanuclear fluoroalkoxide. Its X-ray structure determination showed its formulation to correspond to Ba₅(μ₅-OH)[μ₃-OCH(CF₃)₂]₄[μ₂-OCH(CF₃)₂]₄ [OCH(CF₃)₂](THF)₄(H₂O)·THF. The metallic core is based on a square pyramid encapsulating an hydroxo ligand. In addition to the barium---alkoxide bonds [2.53(3)–2.86(3) Å] neutral O-donors, four THF [2.82(2)–2.86(3) Å] and one H₂O [2.79(3) Å] and secondary barium---fluorine interactions [2.99(2)–3.31(2) Å] ensure high coordination numbers, from 9 to 11 for the metal centers. Hydrogen bonding between the apical fluoroisopropoxide, the water molecule and one THF molecule, non-bonded to a metal center, accounts for the stability of the hydrate and illustrates the Lewis acidity of fluoroalkoxides. Thermal decomposition leads to BaF₂.     

Ab initio study of H2SO4 rotamers

This work uses ab initio calculations to obtain harmonic frequencies and anharmonic constants for the O–H symmetric and asymmetric stretches of H₂SO₄ in its C₂, C_s, C_1a, and C_1b configurations. In addition, a high-resolution potential energy surface is calculated as a function of both O=S–O–H dihedral angles in order to accurately obtain minimum and saddle point energies. The resulting peak positions and Boltzmann populations are compared to experimental frequencies and intensities and provide evidence for the assignment of rotamers in H₂SO₄ as suggested in recent work.     

Velocity map imaging of the photolysis of n-C4H9Br in UV region

Using velocity map ion imaging technique, the photodissociation of n-C₄H₉Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C₄H₉Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in C_s symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C₄H₉+Br (²P_3/2) or C₄H₉ + Br^* (²P_1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C₄H₉Br near 234 nm and 267 nm.     

Effect of TiO2 addition on the crystallization and tribological properties of MgO–CaO–SiO2–P2O5–F glasses

The kinetic parameters including the activation energy for crystallization (E), the Avrami parameter (n) and frequency factor (υ) of a glass in the MgO–CaO–SiO₂–P₂O₅–F system were studied using non-isothermal differential thermal analysis (DTA) with regard to small amount of TiO₂ additions. It has been shown that the role of TiO₂ changes from a glass network former to a glass network modifier with increasing TiO₂ content in this system. The kinetic parameters of the crystallizing phases, apatite and wollastonite, indicated changes accompanied with TiO₂ additions, implying that the TiO₂ is an effective nucleating agent for promoting the crystallization of apatite and wollastonite. The most effective addition is of about 4 wt% TiO₂ in this system. The wear rate and friction coefficient decreased from 1.8 ± 0.1 to 0.9 ± 0.2 and 0.87 to 0.77, respectively, when 4 wt% TiO₂ was incorporated to the base glass.     

Low-temperature heat capacity and thermodynamic properties of crystalline [Re2(Ala)4(H2O)8](ClO4)6 (Re = Eu, Er; Ala = alanine)

[Re₂(Ala)₄(H₂O)₈](ClO₄)₆ (Re=Eu, Er; Ala=alanine) were synthesized, and the low-temperature heat capacities of the two complexes were measured with a high-precision adiabatic calorimeter over the temperature range from 80 to 370 K. For [Eu₂(Ala)₄(H₂O)₈](ClO₄)₆, two solid–solid phase transitions were found, one in the temperature range from 234.403 to 249.960 K, with peak temperature 243.050 K, the other in the range from 249.960 to 278.881 K, with peak temperature 270.155 K. For [Er₂(Ala)₄(H₂O)₈](ClO₄)₆, one solid–solid phase transition was observed in the range from 270.696 to 282.156 K, with peak temperature 278.970 K. The molar enthalpy increments, ΔH_m, and entropy increments,ΔS_m, of these phase transitions, were determined to be 455.6 J mol⁻¹, 1.87 J K⁻¹ mol⁻¹ at 243.050 K; 2277 J mol⁻¹, 8.43 J K⁻¹ mol⁻¹ at 270.155 K for [Eu₂(Ala)₄(H₂O)₈](ClO₄)₆; and 4442 J mol⁻¹, 15.92 J K⁻¹ mol⁻¹ at 278.970 K for [Er₂(Ala)₄(H₂O)₈](ClO₄)₆. Thermal decompositions of the two complexes were investigated by use of the thermogravimetric (TG) analysis. A possible mechanism for the thermal decomposition is suggested.     

Synthesis and characterization of planarly chiral nonbridged bis(1-R-indenyl) zirconium dichloride complexes and X-ray structure of rac-[(η-C9H6-1-C(CH3)2---o-C6H4---OCH3)2ZrCl2]·THF

Reactions of the lithium salts of 3-substituted indenes 1, 2 with ZrCl₄(THF)₂ gave two series of nonbridged bis(1-substituted)indenyl zirconocene dichloride complexes. Fractional recrystallization from THF–petroleum ether furnished the pure racemic and mesomeric isomers of [(η⁵-C₉H₆-1-C(R¹)(R²)---o-C₆H₄---OCH₃)₂ZrCl₂]·nTHF (R¹=R²=CH₃, n=1, rac-1a and meso-1b; R¹=CH₃, R²=C₂H₅; n=0.5 or 0, rac-2a and meso-2b), respectively. Complex 1a was further characterized by X-ray diffraction to have a C₂ symmetrically racemic structure, where the six-member rings of the indenyl parts are oriented laterally and two o-CH₃O---C₆H₄---C(CH₃)₂--- substituents are oriented to the open side of the metallocene (Ind: bis-lateral, anti; Substituent: bis-central, syn). The four zirconocene complexes are highly symmetrical in solution as characterized by room temperature ¹H-NMR, however ¹H–¹H NOESY of meso-1b shows that some of the NOE interactions arise from the two separated indenyl parts of the same molecule, which can only be well explained by taking into account the torsion isomers in solution.     

Solid state synthesis of lithiated manganese oxides from mechanically activated Li2CO3–Mn3O4 mixtures

The solid state formation of lithium manganese oxides has been studied from the thermal decomposition of mixtures Li₂CO₃–Mn₃O₄ with X_Li (lithium cationic fraction)=0.33 (LiMn₂O₄), 0.50 (LiMnO₂) and 0.66 (Li₂MnO₃). The analysis of the reactivity has been performed mainly by thermoanalytical (TG/DSC) and diffractometric (XRPD) techniques either on physical mixtures and on mixtures subjected to mechanical activation by high energy milling. At X_Li=0.33, the cubic lithium manganese spinel oxide (LiMn₂O₄) forms in air. TG measurements showed that the reaction starts at a considerably lower temperature in the activated mixture. By variable temperature X-ray diffraction it has been assessed that, upon mechanical activation, LiMn₂O₄ forms directly and its formation is completed within 700 °C whereas, starting from a physical mixture, the formation goes through Mn₂O₃ and is complete only at 800 °C. At T>820 °C LiMn₂O₄ reversibly decomposes to LiMnO₂ and Mn₃O₄ with an enthalpy of 30.05 kJ mol⁻¹ of LiMn₂O₄. At X_Li=0.50, by annealing under nitrogen flow for 6 h at 650 °C the activated mixture, the orthorhombic LiMnO₂ is formed. Such a formation goes through a mixture of LiMnO₂ and LiMn₂O₄. The enthalpy of LiMnO₂ solid state formation from the activated mixture has been determined to be 57.4 kJ mol⁻¹ of LiMnO₂. At X_Li=0.66 in air the mechanical activation considerably lowers the temperature within the monoclinic phase Li₂MnO₃ forms. Besides the reaction enthalpy could be determined as 40.13 kJ mol⁻¹ of Li₂MnO₃. The reaction, when performed under nitrogen flow, goes through the formation of LiMnO₂. Such a first stage of the reaction is affected by the temperature of reaction rather than by mechanical activation. The activation greatly enhances the second stage of the reaction leading from LiMnO₂ to Li₂MnO₃.     

Heat capacities of the tungsten oxides WO3, W20O58, W18O49 and WO2

The heat capacities of the tungsten oxides WO₃, W₂₀O₅₈, W₁₈O₄₉ and WO₂ have been measured over the temperature range 340–999 K using differential scanning calorimetry. The lower oxides were prepared by controlled reduction of WO₃ in H₂/H₂O gas atmospheres. Previous calorimetric work on WO₃ is confirmed in the temperature range 340–800 K, however, significant increases in heat capacity were observed in the range 800–999 K prior to the orthorhombic—tetragonal phase transition. W₂₀O₅₈ is shown to behave similarly to WO₃. A high temperture phase change is evident, however, this appears to be complete by 970–990 K. The measured values of heat capacity for W₁₈O₄₉ are in close agreement with estimated data for W₁₈O₄₉. There is no evidence of any phase transitions for this oxide in the temperature range studied. The heat capacity data for WO₂ confirm previous drop calorimetry measurements and give no evidence of any phase changes for WO₂ in the temperature range 340–990 K.     

Dinuclear transition metal compounds of a decadentate pyrazole-containing chelating ligand. X-ray crystal structure of Co2(tthd)(ClO4)4(H2O)2(MeOH)1.75

A potentially decadentate ligand, 1,1,4,7,10,10-hexakis(3,5-dimethyl-1-pyrazolylmethyl)-1,4,7,10-tetraazadecane (tthd), has been synthesized from the reaction of tri-ethylenetetramine with six equivalents of N-hydroxymethyl-3,5-dimethylpyrazole. The tthd ligand forms coordination compounds, M₂(tthd)(ClO₄)₄(H₂O)_x, when M is Co, Ni, Cu, Zn and Cd and x = 4–8; and M₂(tthd)(A)₂(ClO₄)₂(H₂O)_x when M is Co and Ni, A is NCS or Cl, and x = 4–8. The cobalt compound, Co₂(tthd)(ClO₄)₂(H₂O)₂(MeOH)_1.75, crystallizes in the triclinic space group P1, a = 1.959(2), b = 1.5657(3), c = 2.1244(3) nm, = 105.5(1), β = 96.9(1), γ = 112.1(1). Due to severe disorder of the anions the structure could only be refined to an R_w, value of 0.099. The ligand acts as a decadentate, dinucleating ligand. The cobalt ions are distorted octahedrally surrounded by five N-atoms of the tthd ligand and an O-atom of water occupying the sixth coordination place. The other perchlorate compounds have very similar structures, as can be concluded from spectroscopic data.

In the thiocyanate and chloride compounds the anions have replaced the coordinated water molecules, resulting in octahedral Ni compounds. With Co thiocyanate, however, tthd acts as an octadentate ligand, resulting only in five-coordinated compounds.     

Concerning the crystal structure of BrF3·AuF3

Crystals of the adduct, BrF₃·AuF₃, are monoclinic, with: a=5.356(4) Å, b=5.766(4) Å, c=8.649(3) Å, β=101.39(4)°, V=261.8(5) Å³, z=2, D_c=4.96 g/cm³. An ordered structure in P2₁ was found, but is of low precision (R₁=0.082) because of crystal deformation. The structure has planar BrF₄ units sharing F ligands cis with planar AuF₄ groups, each AuF₄ being similarly linked to two BrF₄. This generates a ribbon, creased at the bridging F along y, the gold on one side of the crease, the bromine on the other. Such ribbons are stacked parallel along y, with nearest neighbors related by twofold screw axes. This sandwiches each AuF₄ strip of a ribbon symmetrically between like strips. These contacts between the Au-strips bring up, to each Au-atom, two “non-bridging Au–F ligands” of each of the two neighboring strips, to give eight coordination in F. The bromine side of the creased ribbon is unsymmetrically sandwiched between a screw-axis related relative, and the edge of a Au-containing strip oriented almost perpendicular to it. This brings two non-bridging F of the nearest-strip BrF₄ and two non-bridging F of the AuF₄ strip into the secondary cordination sphere of the Br atom. Raman spectra of the BrF₃·AuF₃, molecular BrF₃, and polymeric AuF₃ suggest that the Br–F and Au–F stretching vibrations of BrF₃·AuF₃ are shifted slightly from those of the parent BrF₃ and AuF₃, and indicate some BrF₂⁺AuF₄⁻ character.