Structure of Aqueous Gallium(III) Bromide Solutions Over a Temperature Range 80–333 K by Raman Spectroscopy, X-ray Absorption Fine Structure, and X-ray Diffraction

The structure and complex formation of concentrated aqueous gallium(III) bromide (GaBr₃) solutions have been investigated over a temperature range 80–333 K by Raman spectroscopy, X-ray absorption fine structure (XAFS), and X-ray diffraction. The Raman spectra obtained at various [Br^?]/[Ga³⁺] molar ratios and temperatures have shown that complex formation between Ga³⁺ and Br^? occurs as a predominant species, with [GaBr₄]^? at [Ga³⁺] as high as 1～2 M (M = mol?dm ^?3) and [Br^?]/[Ga³⁺] ratios > ～2, and that cooling of the solutions favors the formation of the aqua Ga³⁺. The intermediate species were not seen in the Raman spectra. The XAFS data have revealed that the aqua complex has a sixfold coordination as [Ga(H₂O)₆]³⁺ with a Ga³⁺–H₂O distance of (1.96 ± 0.02) Å, whereas the [GaBr₄]^? complex has a Ga³⁺–Br^? distance of (2.33± 0.02) Å, and that vitrification of the aqueous GaBr₃ solution at liquid nitrogen temperature shifts the equilibrium toward the aqua complex. The X-ray diffraction data at different subzero temperatures have shown a tendency of decreasing Ga³⁺–Br^? and increasing Ga³⁺–H₂O interactions with lowering temperature, confirming the preference of aqua Ga³⁺ in the supercooled liquid state as well as in the glassy state. The Ga³⁺–H₂O distance of ～1.8 Å for the tetrahedral coordination was found in a 2.01 M gallium(III) bromide solution with a [Br^?]/[Ga³⁺] ratio of 3.7 and gradually increased to a value of 1.92 Å for octahedral geometry with decreasing temperature, suggesting that equilibrium shifts from [GaBr₄]^? to [Ga(H₂O)₆]³⁺ through intermediate species, [GaBr _n ]^(3?n)+ (n = 2 and 3). The Ga³⁺–Br^? and Br^?–Br^? distances within [GaBr₄]^? with an almost tetrahedral symmetry are (2.35± 0.02) and (3.82± 0.03) Å, respectively. The Ga³⁺ has the second hydration shell at (4.03± 0.03) Å and the hydration of Br^? is characterized with a Br^?–H₂O distance of (3.35± 0.02) Å at all temperatures investigated.     

(Cyclophan-Metall)-Komplexe: Synthese und Kristallstruktur von ([3.3]Paracyclophan)gallium(I)-tetrabromgallat(III)

Cyclophane-Metal Complexes: Synthesis and Crystal Structure of ([3.3]Paracyclophane)gallium(I) Tetrabromogallate(III) [3.3]Paracyclophane forms 1:1 complexes 2a and 2b with both Ga[GaCl₄] and Ga[GaBr₄]. The crystalline products obtained from toluene solution at room temperature are much less sensitive to air and moisture than most other arene complexes of Ga(I). Solubilities in standard organic solvents are very low, suggesting coordination polymers. The X-ray diffraction analysis of 2b confirms the presence of a two-dimensional network. Both aromatic rings of each cyclophane molecule are η⁶-coordinated from the outer side to Ga(I)-atoms. The position of these metal cations is 2.75 Å above the ring centres. The arene rings are parallel within each cyclophane, but tilted by 48.5° with respect to those of the neighbouring cyclophane. The coordination sphere of the Ga(I) centres is completed by two Br-atoms of two GaBr anions, which link the Ga(I) cations to give … Ga[GaBr₄] Ga[GaBr₄]Ga … strands. The double interconnection of the Ga(I)-atoms gives rise to a two-dimensional sheet structure, which is thus different from the structure of the previously described Ga[GaBr₄] complex of [2.2]paracyclophane, where a three-dimensional network was observed.     

On the Existence of the Trimer of Gallium Trichloride in the Gaseous Phase

The dependence of the gallium trichloride saturated and unsaturated vapor pressures on temperature was studied by the static method using a quartz membrane zero‐manometer and taking into account the volume of its working chamber and substance mass. Conclusions about the presence of a distinguishable amount of trimeric molecules along with dimeric and momomeric molecules in the vapor were drawn on the basis of the obtained data. The following rough thermodynamic characteristics of a gaseous trimer of gallium trichloride were calculated: Δ_fH° (Ga₃Cl₉, gas, 298 K) = –1466 kJ · mol^–1. S°(Ga₃Cl₉, gas, 298 K) = 654 J · mol^–1 · K^–1. These data were used to elucidate the composition of the gaseous phase at a total pressure of 1 atm in the temperature range of 400–750 K. The suggested existence of trimeric molecules was not contradicted by vibrational spectroscopic analysis of gallium trichloride saturated vapor.     

Syntheses of [BpBut,Me]AlMe2 and [BpBut,Me]GaMe2: structural comparison of a pair of bis(pyrazolyl)hydroborato aluminum and gallium methyl complexes

The aluminum and gallium dimethyl complexes, [Bp^But,Me]AlMe₂ and [Bp^But,Me]GaMe₂, are readily obtained by the reactions of [Bp^But,Me]Tl with Me₃Al and Me₃Ga, respectively. [Bp^But,Me]AlMe₂ and [Bp^But,Me]GaMe₂ have been structurally characterized by X-ray diffraction, which indicates that the most noticeable difference in these otherwise very similar structures is the C–M–C bond angle, which increases from 118.9(3)° for [Bp^But,Me]AlMe₂ to 124.0(2)° for [Bp^But,Me]GaMe₂.     

Synthesis and Crystal Structures of New Palladium(II)—Gallium(III) Complexes with Bridging Halogenide Ligands

The reaction of palladium(II) bromide or palladium(II) iodide with the respective gallium(III) halogenide in the presence of aromatic solvents leads to the formation of palladium(II) tetrabromo— and tetraiodogallate. The compounds are isostructural {monoclinic, C2/m, Pd[GaBr₄]₂: a = 1267(2), b = 808(1), c = 722(1) pm, β = 94.5(1)°; Pd[GaI₄]₂: a = 1363(1), b = 849.9(4), c = 756.6(7) pm, β = 95.38(3)°}. The structures contain mononuclear complexes Pd[GaX₄]₂, where X^— = Br^— ( 1 ), I^— ( 2 ). The crystal structures of 1 and 2 were determined by single‐crystal X‐ray diffraction. Crystals of both compounds turned out to be similarly twinned.     

Synthesis, structure, and electroconductivity of new radical cation salt [Pd(dddt)2]2GaBr4

A new radical cation salt based on the dithiolate complex Pd(dddt)₂ (dddt=5,6-dihydro-1,4-dithiine-2,3-dithiolate) with the tetrahedral anion [GaBr₄]^? was synthesized. The crystal and molecular structure was determined by XRD analysis. The crystal structure of the salt contains Pd(dddt)₂ cation layers alternating with layers of [GaBr₄]^? anions along thec axis of the unit cell. The cation layers contain stacks of Pd(dddt)₂, with a Pd...Pd distance of 3.011 Å. The electroconductivity of [Pd(dddt)₂]₂GaBr₄, single crystals at room temperature is 0.25 Ohm^?1 cm^?1 and decreases with temperature decrease, the activation energy beingE _a=0.66 eV.     

Characterization and thermal analysis of thiourea and bismuth trichloride complex

A complex of thiourea and bismuth trichloride has been synthesized. Its composition is Bi₃Cl₉[SC(NH₂)₂]₇. Crystallographic data are a = 7.141(2) Å, b = 8.820(3) Å, c = 16.365(5) Å, α = 99.389(4)°, β = 95.422(4)°, γ = 106.177(4)°, triclinic system. There are the mononuclear anion [BiCl₅SC(NH₂)₂]^2? and the dinuclear cation {Bi₂Cl₄[SC(NH₂)₂]₆}²⁺ with the Bi–Cl–Bi bridge bonds in the complex. The electric conductance of the absolute methanol solution contained the complex indicates that the complex is an ionic compound. Raman spectra indicate that the bismuth ion is coordinated by the sulfur atoms of the thiourea. The thermal analysis verifies the structure of complex. The TG–MASS curves show the structure rearrangement in the complex at about 118 °C. The DSC curves and calculation means that the structure rearrangement is irreversible.     

Mechanism of formation of nanosized copper particles in a nanoreactor based on the [LiAl<Subscript>2</Subscript>(OH)<Subscript>6</Subscript>]<Subscript>2</Subscript>[Cuedta]·<Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O supramolecular system

The formation of nanosized copper particles in a nanoreactor based on the [LiAl₂(OH)₆]₂[Cuedta]·nH₂O supramolecular system [Li-Al-Cu(edta)] was studied by the DTA, XRPA, FMR, IR, and mass spectrometry methods. Thermal decomposition of Li-Al-Cu(edta) below 200°C occurs as two-stage removal of the interlayer water molecules. Above 200°C dehydration of [LiAl₂(OH)₆]⁺ metal hydroxide layers occurs simultaneously with destruction of [Cuedta]^2? complexonate ions. The first stage of destruction (below 250–260°C) is a redox process that forms metallic copper and liberates gaseous carbon oxide and dioxide. At higher thermolysis temperatures, other gaseous products evolve (ammonia, hydrogen). The copper phase appeared during thermal decomposition as 20–50 nm isometric particles on the surface, while lenslike copper nanoparticles formed in the bulk substance.     

Synthesis and Structural Characterization of β‐Ketoiminate‐Stabilized Gallium Hydrides for Chemical Vapor Deposition Applications

Bis‐β‐ketoimine ligands of the form [(CH₂)_n{N(H)C(Me)?CHC(Me)?O}₂] (LⁿH₂, n=2, 3 and 4) were employed in the formation of a range of gallium complexes [Ga(Lⁿ)X] (X=Cl, Me, H), which were characterised by NMR spectroscopy, mass spectrometry and single‐crystal X‐ray diffraction analysis. The β‐ketoimine ligands have also been used for the stabilisation of rare gallium hydride species [Ga(Lⁿ)H] (n=2 ( 7 ); n=3 ( 8 )), which have been structurally characterised for the first time, confirming the formation of five‐coordinate, monomeric species. The stability of these hydrides has been probed through thermal analysis, revealing stability at temperatures in excess of 200 °C. The efficacy of all the gallium β‐ketoiminate complexes as molecular precursors for the deposition of gallium oxide thin films by chemical vapour deposition (CVD) has been investigated through thermogravimetric analysis and deposition studies, with the best results being found for a bimetallic gallium methyl complex [L³{GaMe₂}₂] ( 5 ) and the hydride [Ga(L³)H] ( 8 ). The resulting films ( F5 and F8 , respectively) were amorphous as‐deposited and thus were characterised primarily by XPS, EDXA and SEM techniques, which showed the formation of stoichiometric ( F5 ) and oxygen‐deficient ( F8 ) Ga₂O₃ thin films.     

Ba5[CrN4]N: Das erste Nitridochromat(V)

Ba₅[CrN₄]N: The First Nitridochromate(V) Ba₅[CrN₄]N is prepared by reaction of mixtures of Li₃N, Ba₃N₂ and CrN/Cr₂N (1 : 1) (molar ratio Li : Ba : Cr = 3 : 5 : 1) in tantalum crucibles at 700°C with flowing nitrogen (1 atm) within a period of 48 h. After cooling down to room temperature (60°C/h) black-shining single crystals of the ternary phase with a platy habit are obtained (monoclinic, C2/m; a = 1054.0(2) pm, b = 1170.9(3) pm, c = 937.7(2) pm, b? = 110,79(2)°; Z = 4). The crystal structure contains isolated complex anions [Cr^VN₄]^7? which nearly satisfy the ideal tetrahedral symmetry (Cr? N [pm]: 2 × 175.3(4), 2 × 175.8(5); N? Cr? N [°]: 106.8(2), 109.5(2), 2 × 109.9(2), 2 × 110,3(2)). The coordination sphere for each of the terminal nitride functions of the complex anions is completed by five neighbouring Ba²⁺ ions (distorted CrBa₅ octahedra). The octahedra are connected via common CrBa₂ faces as well as CrBa edges thereby forming condensed tetrameric octahedral groups. The isolated nitride ions which are also present in the crystal structure of Ba₅[CrN₄]N are in an octahedral environment of Ba²⁺ ions. The presence of a d¹-System (Cr(V)) is confirmed by magnetic susceptibility data.     

Novel Cyclic Sulfonium‐Based Ionic Liquids: Synthesis,Characterization, and Physicochemical Properties

A new series of ionic liquids composed of three cyclic sulfonium cations and four anions has been synthesized and characterized. Their physicochemical properties, including their spectroscopic characteristics, ion cluster behavior, surface properties, phase transitions, thermal stability, density, viscosity, refractive index, tribological properties, ion conductivity, and electrochemical window have been comprehensively studied. Eight of these salts are liquids at room temperature, at which some salts based on [NO₃]^? and [NTf₂]^? ions exhibit organic plastic crystal behaviors, and all the saccharin‐based salts display relatively high refractive indices (1.442–1.594). In addition, some ionic liquids with the [NTf₂]^? ion exhibit peculiar spectroscopic characteristics in FTIR and UV/Vis regions, whilst those salts based on the [DCA]^? ion show lower viscosities (34.2–62.6 mPa s at 20 °C) and much higher conductivities (7.6–17.6 mS cm^?1 at 20 °C) than most traditional 1,3‐dialkylimidazolium salts.     

Die Kristallstrukturen von SeCl3 +SbCl6−, SeBr3+GaBr4−, PCl4+SeCl5− und (PPh4+)2SeCl42− · 2 CH3CN

Crystal Structures of SeCl₃⁺SbCl₆^?, SeBr₃⁺GaBr₄^?, PCl₄⁺SeCl₅^?, and (PPh₄⁺)₂SeCl₄^2? · 2 CH₃CN The crystal structures of the title compounds were determined by X-ray diffraction. SeCl₃⁺SbCl₆^?: Space group P2₁/m, Z = 4, structure determination with 1795 observed unique reflections, R = 0.022. Lattice dimensions at ?80°C: a = 940.9, b = 1066.3, c = 1234.9 pm, β = 102.79°. The compound forms ion pairs with the structure of a double octahedron with linked surfaces. SeBr₃⁺GaBr₄^?: Space group Pc, Z = 2, structure determination with 1461 observed unique reflections, R = 0.058. Lattice dimensions at ?60°C: a = 660.1, b = 655.3, c = 1431.3 pm, β = 101.177°. The compound crystallizes in the SCl₃[AlCl₄] lattice type. Between the ions there are two relatively short Se … Br? Ga contacts. PCl₄⁺SeCl₅^?: Space group Ima2, Z = 8, structure determination with 1757 observed unique reflections, R = 0.029. Lattice dimensions at ?50°C: a = 1651.6, b = 1201.2, c = 1166.4 pm. The SeCl₅^? ions are associated to chains via interionic Se? Cl … Se contacts along the crystallographic c-axis. (PPh₄⁺)₂SeCl₄^2? · 2CH₃CN: Space group P2₁/n, Z = 2, structure determination with 2578 observed unique reflections, R = 0.050. Lattice dimensions at ?80°C: a = 1288.5, b = 726.0, c = 2585.8 pm, β = 101.65°. The compound includes planar-tetragonal SeCl₄^2? ions, which almost meet D_4h symmetry.     

Indiumwolframat,In2(WO4)3 – ein In3+ leitender Festkörperelektrolyt

Indium Tungstate, In₂(WO₄)₃ – an In³⁺ Conducting Solid Electrolyte Polycrystalline In₂(WO₄)₃ has been electrochemically characterized and unambiguously identified as an In³⁺ conducting solid electrolyte. By heating, indium tungstate undergoes a phase transition between 250 °C and 260 °C transforming from a monoclinic to an orthorhombic phase for which the conduction properties have been determined. The adopted crystal structure in this high temperature region corresponds to the Sc₂(WO₄)₃ type structure. The electrical conductivity was investigated by impedance spectroscopy in the temperature range 300–700 °C and amounts to about 3.7 · 10^–5 Scm^–1 at 600 °C with a corresponding activation energy of 59.5 kJ/mol. Polarization measurements indicated an exclusive current transport by ionic charge carriers with a transference number of about 0.99. In dc electrolysis experiments, the trivalent In³⁺ cations were undoubtedly identified as mobile species. A current transport by oxide anions was not observed.     

Composition of saturated vapor over Ytterbium bromides

The vaporization process of ytterbium di- and tribromide was studied using high-temperature mass spectrometry over the temperature range of 850 to 1300 K. It was ascertained that, at the early vaporization stages, the vapor contained molecules YbBr₃, YbBr₂, YbBr, Br₂, Yb₂Br₂, Yb₂Br₃, Yb₂Br₄, Yb₂Br₅, Yb₂Br₆, and atoms Yb and Br. The partial pressures of all components of saturated vapor were calculated. It was found that vapor composition reflected the course of the reactions of decomposition of tribromide and disproportionation of dibromide in the condensed phase. It was concluded that vaporization of di- and tribromide was incongruent at the initial stages; vaporization of both agents acquired a congruent character with the Yb: Br = 1.0: 1.9_±0.2 ratio with time.     

Vapor pressure and dissociation energy of (In2O)

The vapor pressure of pure liquid indium, and the sum of pressures of (In) and (In₂O) species over the condensed phase mixture {In} + <In₂O₃>, contained in a silica vessel, have been measured by Knudsen effusion and Langmuir free vaporization methods in the temperatue range 600 to 950°C. Mass spectrometric studies reported in the literature show that (In) and (In₂O) are the important species in the vapor phase over the {In} + <In₂O₃ >; mixture. The vapor pressure of (In₂O) corresponding to the reaction,

deduced from the present measurements is given by the equation,

The “apparent evaporation coefficient” for the condensed phase mixture is approximately 0.8. The energy for the dissociation (In₂O) molecule into atoms calculated from the above equation is D°₀ = 180.0 (± 1.0) kcal mol^?1.     

Isolation of a Non‐Heteroatom‐Stabilized Gold–Carbene Complex

Gold–carbene complexes are essential intermediates in many gold‐catalyzed organic‐synthetic transformations. While gold–carbene complexes with direct, vinylogous, or phenylogous heteroatom substitution have been synthesized and characterized, the observation in the condensed phase of electronically non‐stabilized gold–carbenes has so far remained elusive. The sterically extremely shielded, emerald‐green complex [IPr**Au=CMes₂]⁺[NTf₂]^? has now been synthesized, isolated, and fully characterized. Its absorption maximum at 642 nm, in contrast to 528 nm of the red‐purple carbocation [Mes₂CH]⁺, clearly demonstrates that gold is more than just a “soft proton”.     

Sub- and supersolidus phase relations of formamidinium-cesium polyiodides

It has been demonstrated that formamidinium–cesium polyiodides are facile reagents for converting metallic lead into perovskite at temperatures of 20–90 °C. For the first time, a tentative phase diagram of the [HC(NH₂)₂]I–I₂ binary system was proposed, and sub- and supersolidus phase relations in the [HC(NH₂)₂]I–CsI–I₂ ternary system were discussed.     

Improved photocatalytic performance of anatase TiO2 synthesized through ethanol supercritical drying technique

Anatase titania (TiO₂) nanoparticles were synthesized via a self‐developed ethanol vapor‐thermal method at 240°C (T240) and 250°C (T250), i.e. at temperatures lower and higher, respectively, than the supercritical temperature (243.5°C, 7.0 MPa) of ethanol. Compared to T240, T250 exhibited a higher ratio of exposed (001) facets, oxygen vacancies, and concomitant TiO_x. The specific surface area of T250 was 119.0 m² g^?1, smaller than that of T240 (144.2 m² g^?1). During the degradation of methylene blue, T250 exhibited a high apparent rate constant (K_app) of 14.5 × 10^?2 min^?1, which was 6.3 times larger than that for T240. Furthermore, compared to T240, T250 exhibited better performance toward degradation of phenol. Results of electron spin resonance spectroscopy and photoluminescence indicated that the photogenerated electron–hole pairs possessed higher separation efficiency for T250 than for T240. In summary, the excellent photocatalytic performance of T250 originates from the higher ratios of exposed (001) facets, oxygen vacancies or TiO_x, C═O groups adsorbed at the surface of particles, and higher separation efficiency of photogenerated electron–hole pairs. By employing this self‐developed vapor‐thermal method, a variety of catalysts and their composites can be synthesized, which may exhibit novel morphological characteristics and properties as well as excellent photocatalytic performance.     

Synthesis and characterization of N-heterocyclic carbene palladium complex and its application on direct arylation of benzoxazoles and benzothiazoles with aryl bromides

A mixed-halogen bis(1-(4-tert-butylbenzyl)-3-(2, 4, 6-trimethylbenzyl)-1H-benzo[d]imidazol-2-ylidene) palladium(II) complex, trans-[Pd(Cl_0.7Br_0.3)₂(C₂₈H₃₂N₂)₂], has been synthesized and characterized by elemental analysis, ¹H-NMR, ¹³C-NMR, and IR spectroscopy, and single crystal X-ray diffraction. The palladium in the mononuclear complex is four-coordinate in a square-planar configuration with two carbenes of two benzo[d]imidazole rings and two halides. The two halides are disordered between Br and Cl, with the Cl: Br ratio approximately 0.7 : 0.3. The angles C1–Pd1–Br1, 88.63(11)° and C1ⁱ–Pd1–Br1ⁱ, 91.37(11)° (i: 1?x, 1?y, 1?z) in the coordination sphere are very close to the ideal value of 90°. The Pd–X distance is slightly longer than other carbene derivative Pd–Cl single bond distances and slightly shorter than Pd–Br single bond distances. These results agree with the Cl/Br disorder at the halogen position. The palladium–carbene complex was tested as a catalyst in the direct arylation reaction of benzoxazoles and benzothiazoles with aryl bromides.     

Structure of bis-(1,1,1-trifluoro-2-(methylimino)pentanoato-4)copper(II). Thermal properties of N-methylsubstituted copper(II) β-iminoketonates

The single crystal X-ray diffraction (XRD) method was used to determine the structure of the [Cu(mi-tfac)₂] (mi-tfac = MeC(O)CHC(NMe)CF₃) complex at the temperature of 150 K. The crystallographic data are as follows: space group Pnna, a = 11.8798(16) Å, b = 12.0315(16) Å, c = 10.6259(14) Å, V = 1518.8(4) ų, Z = 4, R = 0.0288. The structure is molecular, the coordination environment of copper in the molecule adopts a distorted tetrahedral geometry. The Cu–O and Cu–N distances are 1.9182(13) Å and 1.9610(16) Å respectively, the OCuN chelate angle is 94.18(5)°. The thermal properties of the compounds [Cu(mi-tfac)₂] and [Cu(RC(O)CHC(NMe)R)₂] (R = Me, ^t Bu) in the condensed phase have been studied by the methods of thermogravimetry and differential scanning calorimetry. The thermodynamic characteristics of the melting processes have been determined.