Untersuchungen zum System Ge/I

Investigations on the System Ge/I The enthalpy and entropy of evaporation of GeI₄ was determined by measurements of the pressure over liquid GeI₄. The values for the decomposition reaction 2GeI₂, s = Ge, s + GeI₄, g and the sublimation of GeI₂ were derived from measurements of the total pressure over solid GeI₂. The measurements of the total pressure above the saturation ranges of GeI₄, and GeI₂, s in dependence of the mass employed and the temperature gives a sat of data, from which the values of the enthalpies of formation and the standard entropies of GeI₄, g and GeI₂g, respectively, result.     

Ge−Fe Carbonyl Cluster Compounds: Ionic Liquids-Based Synthesis,Structures, and Properties

Nine Ge−Fe carbonyl cluster compounds are prepared via ionic liquids-based synthesis. This includes the novel compounds [EMIm][Fe(CO)₃I(GeI₃)], [EHIm][Fe(CO)₃I(GeI₃)], [BMIm][GeI₂{Fe(CO)₄}₂(μ-I)][AlCl₄]₂, [GeI₂{Fe(CO)₄}₂(μ-I)][Fe(AlBr₄)₃], [BMIm]₂[(FeI₂)_0.75{Fe(CO)₂I(GeI₃)₂}₂], and [EHIm][Fe(CO)₄(GeI₂)₂Fe(CO)₃GeI₃] as well as the previously reported compounds (Fe(CO)₄(GeI₃)₂, FeI₄{GeI₃Fe(CO)₃}₂, and Ge₁₂{Fe(CO)₃}₈(μ-I)₄ (EMIm: 1-ethyl-3-methylimidazolium, EHIm: 1-ethylimidazolium, BMIm: 1-butyl-3-methylimidazolium). With this series of compounds, a comparison of synthesis conditions and structural features is possible and, for instance, allows correlating the composition and structure of the respective Ge−Fe carbonyl cluster compounds with the type and acidity of the ionic liquid. With [EMIm][{GeI₃}₂Fe(CO)₃I], moreover, we can exemplarily show the thermal decomposition as a single-source precursor in the ionic liquid, resulting in bimetallic Ge−Fe nanoparticles with small size and narrow size distribution (7.0±1.4 nm).     

Germanium- and Tin-Catalyzed Living Radical Polymerizations of Styrene and Methacrylates

Summary : Ge and Sn (non-transition-metal) catalyzed living radical polymerizations were developed. Low-polydispersity (M_w/M_n ∼ 1.1–1.3) polystyrenes, poly(methyl methacrylate)s, poly(glycidyl methacrylate)s, and poly(2-hydroxyethyl methacrylate) with predicted molecular weights were obtained with a fairly high conversion in a fairly short time. The pseudo-first-order activation rate constant k_act for the styrene/GeI₄ (catalyst) system was large enough, even with a small amount of GeI₄, to explain why the system provides low-polydispersity polymers from an early stage of polymerization. The retardation in the polymerization rate observed for the styrene/GeI₄ system was kinetically proved to be mainly due to the cross-termination between the propagating radical with GeI. Attractive features of the Ge and Sn catalysts include their high reactivity hence small amounts (1–5 mM) being required under a mild condition (at 60–80 °C), high solubility in organic media without ligands, insensitivity to air hence sample preparation being allowed in the air, and minor color and smell. The Ge catalysts may also be attractive for their low toxicity.     

Mass spectrometric determination of the heats of formation of the silane bromides

The reaction of SiBr₄(g) with H₂(g) in the temperature range 900–1143 K has been studied by a mass spectrometric method. Second and third law reaction enthalpies were obtained for SiBr₄(g) + H₂(g) = SiHBr₃(g) + HBr(g), SiHBr₃(g) + H₂(g) = SiH₂Br₂(g) + HBr(g), and SiH₂Br₂(g) + H₂(g) = SiH₃Br(g) + HBr(g). From the heats of reaction, third-law ΔH_£298 values of ?72.5 ± 1, ?43.2 ± 1.5 and ?15.3 ± 0.5 kcal/mole were obtained for SiHBr₃(g), SiH₂Br₂(g), and SiH₃Br(g), respectively.     

Synthesis,structure characterization,and thermochemistry of the coordination compounds of pyridine-2,6-dicarboxylic acid with several metals (Ca and Co)

Two solid state complexes of pyridine-2,6-dicarboxylate with Ca²⁺ and Co²⁺ ions, Ca₂(DPC)₂(H₂O)₆(H₂DPC)₂(s) and Co(DPC)₂·Co(H₂O)₅·2H₂O(s), were synthesized. X-ray crystallography was applied to characterize the crystal structures of the two complexes. The molecular and cell stacking structures of the two complexes were shown; the crystal data and refinement details were summarized, and the selected bond lengths and angles of the title complexes were listed. Low-temperature heat capacities of the two complexes were measured with an automated adiabatic calorimeter in the temperature ranging from 78 to 380 K. Two polynomial equations of experimental molar heat capacities as a function of the temperature were obtained by the least-squares method. The smoothed molar heat capacities and thermodynamic functions of the complexes were calculated based on the fitted polynomial equations. In addition, thermodynamic properties of the two complexes were compared.     

Electron affinities of higher molybdenum fluorides as determined by the effusion technique

The effusion technique with mass spectral recording of ions was employed to investigate the ionic component of molybdenum trifluoride saturated vapour. The equilibrium constants of ion—molecular reactions involving MoF₅^?, MoF₆^? and MoOF₄^? were measured. The following thermodynamic values were obtained from experimental data: MoF₄(g) + F^?(g) = MoF₅^?(g),ΔH₂₉₈⁰ = ?382.0 ± 20.1 kJ/mole; MoF₅(g) + F^?(g) = MoF₆^?(g), ΔH₂₉₈⁰ = ?413.4 ± 20.1 kJ/mole; MoOF₃(g) + F^?(g) = MoOF₄^?, ΔH₂₉₈⁰ = ?418.0 ± 20.5 kJ/mole; EA(MoF₅ = 3.6 ± 0.2 eV, EA(MoF₆) = 3.6 ± 0.2 eV, EA(MoOF₄) = 4.0 ± 0.4 eV. Reported as well as estimated molecular constants were used to calculate thermodynamic functions of some participants of ion—molecular reactions. For MoOF₃, BeF₃^? and Be₂F₅^? vibration frequencies were calculated from the estimated force field.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 7. Die Kristall- und Molekülstruktur des Diphosphagermetans (t-BuP)2(GePh2)2

Structural Chemistry of Phosphorus Containing Chains and Rings. 7. Molecular and Crystal Structure of the Diphosphagermetane (t-BuP)₂(GePh₂)₂ The compound 1,2-di-tert-butyl-3,3,4,4-tetraphenyl-diphospha-3,4-digerma-cyclobutan, (t-BuP)₂(GePh₂)₂, crystallizes monoclinically in the space group P2₁/c with a = 996.8 pm, b = 1337.3 pm, c = 2403.4 pm, β = 92.66° and Z = 4 formula units. The main structural feature is a non-planar four-membered ring. The (average) bond lengths are d(Ge? Ge) = 242.1 pm, d(Ge? P) = 234.0 pm, d(P? P) = 221.6 pm, d(Ge? C) = 194.9 pm, d(P? C) = 188.tyl4 pm, d(C? C)_Ph = 136.l5 pm, d(C? C)_t-Bu = 151.8 pm, d(C? H)_Ph = 91 pm, d(C? H)_t-Bu ? 95 pm. The geometry of the substituents phenyl and tert-butyl is quite normal.     

Supramolecular assemblies of germanium(II) halides with O-, S- and Se-donor macrocycles - the effects of donor atom type upon structure

Reaction of [GeCl(2)(dioxane)] with [18]aneS(6) (1,4,7,10,13,16-hexathiacyclooctadecane) gives the neutral [GeCl(2)([18]aneS(6))] which forms a supramolecular sheet network involving exocyclic coordination, with the macrocycles bridging Ge atoms which are in a pseudo-trigonal bipyramidal environment from two Cl and two S atoms (saw-horse), with one lone pair assumed to occupy the remaining equatorial void. Conversely, using the mixed S/O macrocycles [18]aneS(3)O(3) (1,4,7-trithia-10,13,16-trioxacyclooctadecane) and [15]aneS(2)O(3) (1,4-dithia-7,10,13-trioxacyclopentadecane) (L) leads to the monocationic pentagonal pyramidal [GeCl(L)](+) whose structures show endocyclic Ge coordination, and displacement of one Cl. The Ge-S and Ge-O bond lengths are surprisingly disparate in these two complexes, and in the former the coordinated Cl is axial, while in the latter it occupies the pentagonal plane (with an S atom axial). Cyclic selenoethers form one-dimensional or two-dimensional supramolecular assemblies with Ge(ii) halides, including [GeCl(2)([8]aneSe(2))] ([8]aneSe(2) = 1,5-diselenacyclooctane), [(GeCl(2))(2)([16]aneSe(4))] ([16]aneSe(4) = 1,5,9,13-tetraselenacyclohexadecane), [GeBr(2)([16]aneSe(4))] and [(GeI(2))(2)([16]aneSe(4))]·GeI(4)- these represent the first germanium species with selenoether ligation. Structural studies on each of these show exocyclic GeX(2) coordination, giving networks based upon Se(2)X(2) coordination at Ge(ii) with a distorted pseudo-trigonal bipyramidal environment in which the Ge-based lone pair is assumed to occupy the vacant equatorial vertex. Further weak GeX contacts are also evident in some cases. The weak, secondary GeS/Se and GeX interactions that pervade these systems may be regarded as a further type of supramolecular interaction allowing assembly of new network structures, and the long II contacts evident between the GeI(2) and GeI(4) units in [(GeI(2))(2)([16]aneSe(4))]·GeI(4) probably provide a small thermodynamic contribution leading to co-crystallisation of ordered GeI(4) molecules within the network.     

Strukturelle Vielfalt im pseudo‐ternären System M/Ge/I: α‐[NMe(nBu)3](GeI4)I, β‐[NMe(nBu)3](GeI4)I und [ImMe(nBu)][N(nBu)4](GeI4)3I2

By reaction of GeI₄, [N(nBu)₄]I as iodide donor, and [NMe(nBu)₃][N(Tf)₂] as ionic liquid, reddish‐black, plate‐like shaped crystals are obtained. X‐ray diffraction analysis of single crystals resulted in the compositions ;alpha;‐[NMe(nBu)₃](GeI₄)I (Pbca; a = 1495.4(3) pm; b = 1940.6(4) pm; c = 3643.2(7) pm; Z = 16) and β‐[NMe(nBu)₃](GeI₄)I (Pn; a = 1141.5(2) pm; b = 953.6(2) pm; c = 1208.9(2) pm; β = 100.8(1)°; Z = 2). Depending on the reaction temperature, the one or other compound is formed selectively. In addition, the reaction of GeI₄ and [N(nBu)₄]I, using [ImMe(nBu)][BF₄] (Im = imidazole) as ionic liquid, resulted in the crystallization of [ImMe(nBu)][N(nBu)₄](GeI₄)₃I₂ (P2₁/c; a = 1641.2(3) pm; b = 1903.0(4) pm; c = 1867.7(4) pm; β = 92.0(1)°; Z = 4). The anionic network of all three compounds is established by molecular germanium(IV)iodide, which is bridged by iodide anions. The different connectivity of (GeI₄–I^–) networks is attributed to the flexibility of I^– regarding its coordination and bond length. Here, a [3+1]‐, 4‐ and 5‐fold coordination is first observed in the pseudo‐ternary system M/Ge/I (M: cation).     

Standard Gibbs free energy of formation of SnO2 from high-temperature e.m.f. measurements

The thermodynamic equilibrium Sn(l) + O₂(g) = SnO₂(s) has been studied between 773 and 1380 K by e.m.f. measurements on cells involving a solid electrolyte, of the type:

$\text{Pt∥Ni(s), NiO(s)∥ZrO}{}_2\text{+ Y}{}_2\text{O}{}_3\text{∥Sn(1), SnO}{}_2\text{(s)∥Pt}$

     

The Equilibrium Partial Pressure of HgI2 over and Thermodynamic Properties of Hg3Te2I2 1)

The high temperature vaporization pattern of Hg₃Te₂I₂(s,l) shows four distinctly different regimes, similar to those of the HgTe vaporization. The most predominant species in the vapor phase in all four regimes is HgI₂(g), followed by Hg(g) and, possibly, Te₂I₂(g). The width of the “homogeneity range” of Hg₃Te₂I₂(s) was determined to be less than about 0.17 mole‐% HgI₂. Applying the second‐law method to the vaporization of HgTe‐saturated Hg₃Te₂I₂(s) at higher temperatures yields the heat and entropy of vaporization of 20.9 ± 2.3 (kcal/mole) and of 27.5 ± 2.8 (cal/mole K), respectively, with estimated total uncertainties of less than ± 5.8 (kcal/mole) and ± 7.6 (cal/mole K), at an average temperature of 722 K. With an estimated heat capacity function of Hg₃Te₂I₂(s) and estimated thermodynamic values for HgI₂‐saturated HgTe(s), the heat of formation and absolute entropy of Hg₃Te₂I₂(s) are computed to be = ?49.7 ± 1.1 (kcal/mole) and = 97.3 ± 1.4 (cal/mole K), with estimated total uncertainties of ± 8.3 (kcal/mole) and ± 14.0 (cal/mole K). The combined results of this investigation provide valuable information for the crystal growth of this material from the vapor and molten phase.     

Mass Spectrometric Investigations of Thermodynamic Properties of the RbCl/GdCl3 System

The vaporization of pure RbCl, GdCl₃, and RbCl‐GdCl₃ samples of different phase compositions was investigated in the temperature range between 666 K and 982 K by use of the Knudsen effusion mass spectrometry. The gaseous species RbCl, Rb₂Cl₂, GdCl₃, and RbGdCl₄ were identified in the equilibrium vapours and their partial pressures were determined. The enthalpy of dissociation of RbGdCl₄(g), Δ_dissH°(859 K) = 263.1 ± 7.7 kJ mol^—1, was evaluated by second law treatment of the equilibrium partial pressures. The thermodynamic activities of RbCl and GdCl₃ were obtained at 800 K in the two‐phase fields {Rb₃GdCl₆(s) + liquid} and {RbGd₂Cl₇(s) + GdCl₃(s)}. The Gibbs free energies of formation of the pseudo‐binary phases Rb₃GdCl₆(s), Δ_fG°(800 K) = —75.1 ± 2.5 kJ mol^—1 and RbGd₂Cl₇(s), Δ_fG°(800 K) = —40.6 ± 1.2 kJ mol^—1, were evaluated from the thermodynamic activities of the components. The results are compared with the available literature data.     

Vaporization chemistry and thermodynamics in the CdGa2S4-Ga2S3 system

The chemistry and thermodynamics of vaporization of CdGa₂S₄(s), CdGa₈S₁₃(s), and Ga₂S₃(s) were studied by computer-automated, simultaneous Knudsen-effusion and torsion-effusion, vapor pressure measurements in the temperature range 967–1280 K. The vaporization was incongruent with loss of Cd(g) + 1/2 S₂(g) and production of CdGa₈S₁₃(s), a previously unknown compound, in equilibrium with CdGa₂S₄(s), until the solid became CdGa₈S₁₃ only. Then, incongruent vaporization continued with production of Ga₂S₃(s) until the solid was Ga₂S₃ only. The latter vaporized congruently. The ΔH°(298 K) of combination of one mole of CdS(s) with one mole of Ga₂S₃(s) to give CdGa₂S₄(s) was ?22.6 ± 0.9 kJ mole^?1. The 2H2(298 K) of combination of one mole of CdS(s) with four moles of Ga₂S₃(s) to give CdGa₈S₁₃(s) was ?25.5 ± 1.1 kJ mole^?1. The 2H2(298K) of CdGa₈S₁₃(s) with respect to disproportionation into CdGa₂S₄(s) and 3 Ga₂S₃(s) was ?2.8 ± 0.6 kJ mole^?1. CdGa₈S₁₃(s) was not observed at room temperature. The 2H2(298 K) of vaporization of the residual Ga₂S₃(s) was 663.4 ± 0.8 kJ mole^?1, which compared well with a value of 661.4 ± 0.3 kJ mole^?1 already available from the literature. Implications of small variations in stoichiometry of compounds in this study were observed and are discussed.     

Organosilyl/‐germyl Polyoxotungstate Hybrids for Covalent Grafting onto Silicon Surfaces: Towards Molecular Memories

Organosilyl/‐germyl polyoxotungstate hybrids [PW₉O₃₄(tBuSiO)₃Ge(CH₂)₂CO₂H]^3? ( 1 a ), [PW₉O₃₄(tBuSiO)₃Ge(CH₂)₂CONHCH₂C?CH]^3? ( 2 a ), [PW₁₁O₃₉Ge(CH₂)₂CO₂H]^4? ( 3 a ), and [PW₁₁O₃₉Ge(CH₂)₂CONHCH₂C≡CH]^4? ( 4 a ) have been prepared as tetrabutylammonium salts and characterized in solution by multinuclear NMR spectroscopy. The crystal structure of (NBu₄)₃ 1 a? H₂O has been determined and the electrochemical behavior of 1 a and 2 a has been investigated by cyclic voltammetry. Covalent grafting of 2 a onto an n‐type silicon wafer has been achieved and the electrochemical behavior of the grafted clusters has been investigated. This represents the first example of covalent grafting of Keggin‐type clusters onto a Si surface and a step towards the realization of POM‐based multilevel memory devices.     

Thermodynamic Modeling of Aqueous Aluminum Chemistry and Solid-Liquid Equilibria to High Solution Concentration and Temperature. I. The Acidic H-Al-Na-K-Cl-H2O System from 0 to 100 °C

In this paper, we describe the development of a thermodynamic model that calculates solute/solvent activities and solid-liquid equilibria in the acidic aluminum system, H-Al³⁺-Na-K-Cl-H₂O, to high molality from 0?° to ≈100?°C. The model incorporates the concentration-dependent, specific interaction equations for aqueous solutions of Pitzer (Activity Coefficients in Electrolyte Solutions, 2nd edn., pp. 75–153, CRC Press, Boca Raton, 1991). Parameterization of this model adds Al³⁺ specific interactions in the binary Al-Cl-H₂O and ternary Al-H-Cl-H₂O, Al-Na-Cl-H₂O and Al-K-Cl-H₂O systems as well as the standard chemical potentials of AlCl₃?6H₂O(s) and Al(OH)₃(s) (gibbsite) in the 0?° to 100?°C range to our variable temperature (0–250?°C) model of acid-base reactions in the H-Na-K-OH-Cl-HSO₄-SO₄-H₂O system (Christov and Moller in Geochim. Cosmochim. Acta 68:1309, 2004). In constructing our aluminum model, we used Emf, osmotic, equilibrium constant and solubility data. New Emf measurements using the cell Pt|H₂(g, 101.325 kPa)|HCl(m ₁), AlCl₃(m ₂)|AgCl(s)|Ag|Pt at temperatures ranging from 0 to 45?°C and at total ionic strength ranging from 0.1 to 3 mol?kg^?1 are presented. Gibbsite and boehmite, AlOOH(s), solubility data are used in testing the model. Limitations of the model due to data insufficiencies are discussed.     

Aqueous partial molar heat capacities and volumes for NaTcO4 and NaReO4

A flow microcalorimeter/densimeter system has been commissioned to measure heat capacities and densities of solutions containing radioactive species as a function of temperature. Measurements were made for NaTcO₄(aq) at six temperatures (189.15 K to 373.15 K for the heat capacities, 287.43 K to 396.67 K for the densities) over the molality range 0.01 to 0.29 mol-kg^–1. Measurements for NaReO₄(aq) (NaReO₄ is a common nonradioactive analogue for NaTcO₄) were made under similar conditions, but for eight temperatures and a more extensive range of molalities, 0.05 to 0.65 mol-kg^–1. Heat capacities of NaCl(aq) reference solutions were also measured from 293.15 K to 398.15 K.The heat capacity and density data are analysed using Pitzer's ioninteraction model. Equations for the apparent molar heat capacities and volumes are reported. Values of the NaReO₄(aq) partial molar heat capacities are compared to literature values based on integral heats of solution. The agreement between the two sets of NaReO₄ results is good below 330 K, but only fair at the higher temperatures. Values of the partial molar volumes have also been derived. Using literature values and the results of our experiments, it is calculated that the disproportionation of hydrated TcO₂(s) to form TcO ₄ ^– (aq) and Tc(cr) occurs more readily at high temperatures. The uncertainties introduced by using thermodynamic values for ReO ₄ ^– (aq), in the absence of values for TcO ₄ ^– (aq), are discussed.     

Synthesis and characterization of novel blue emitting Na2CaSiO4:Ce3+ phosphor

The blue phosphors Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ were synthesized by the sol–gel method and their luminescence characteristics were investigated for the first time. Structural information about prepared samples is obtained by analyzing the XRD patterns and SEM micrographs. The photoluminescence (PL) excitation spectra indicate that the Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ phosphors can be effectively excited by ultraviolet (360 nm) light. The PL emission spectra exhibit tunable blue broadband emission with the dominant wavelength of 427–447 nm under excitation of 360 nm by controlling the doping concentration of Ce³⁺. The concentration quenching effect for Ce³⁺ was found at the optimum doping concentration of 4 mol%. The Commission Internationale de l’Eclairage 1931 chromaticity coordinates of Na_1.96Ca_0.96SiO₄:0.04Ce³⁺ are (0.1447, 0.0787), which are better color purity compared to the commercial Eu²⁺-doped BaMgAl₁₀O₁₇ phosphor. Na_1.96Ca_0.96SiO₄:0.04Ce³⁺ composition shows intense blue emission (peak wavelength, 439 nm) with relative intensity versus commercial BaMgAl₁₀O₁₇:Eu²⁺ blue phosphor (Nichia) 65 and 158 % under 254 and 365 nm excitation, respectively. All the results indicate that Na_(2?x)Ca_(1?x)SiO₄:xCe³⁺ phosphors are potential candidate as a blue emitting phosphor for UV-converting white light-emitting diodes.     

Thermodynamic studies on SrFe12O19(s), SrFe2O4(s), Sr2Fe2O5(s) and Sr3Fe2O6(s)

The citrate-nitrate gel combustion route was used to prepare SrFe₂O₄(s), Sr₂Fe₂O₅(s) and Sr₃Fe₂O₆(s) powders and the compounds were characterized by X-ray diffraction analysis. Different solid-state electrochemical cells were used for the measurement of emf as a function of temperature from 970 to 1151 K. The standard molar Gibbs energies of formation of these ternary oxides were calculated as a function of temperature from the emf data and are represented as (SrFe₂O₄, s, T)/kJ mol⁻¹ (±1.7)=−1494.8+0.3754 (T/K) (970?T/K?1151). (Sr₂Fe₂O₅, s, T)/kJ mol⁻¹ (±3.0)=−2119.3+0.4461 (T/K) (970?T/K?1149). (Sr₃Fe₂O₆, s, T)/kJ mol⁻¹ (±7.3)=−2719.8+0.4974 (T/K) (969?T/K?1150).Standard molar heat capacities of these ternary oxides were determined from 310 to 820 K using a heat flux type differential scanning calorimeter (DSC). Based on second law analysis and using the thermodynamic database FactSage software, thermodynamic functions such as Δ_fH°(298.15 K), S°(298.15 K) S°(T), C_p°(T), H°(T), {H°(T)-H°(298.15 K)}, G°(T), free energy function (fef), Δ_fH°(T) and Δ_fG°(T) for these ternary oxides were also calculated from 298 to 1000 K.     

Isosaccharinate Complexes of Fe(III)

Prior to this study there were no thermodynamic data for isosaccharinate (ISA) complexes of Fe(III) in the environmental range of pH (>~4.5). This study was undertaken to obtain such data in order to predict Fe(III) behavior in the presence of ISA. The solubility of Fe(OH)₃(2-line ferrihydrite), referred to as Fe(OH)₃(s), was studied at 22?±?2?°C in: (1) very acidic (0.01?mol·dm^?3 H⁺) to highly alkaline conditions (3?mol·dm^?3 NaOH) as a function of time (11?C421?days), and fixed concentrations of 0.01 or 0.001?mol·dm^?3 NaISA; and (2) as a function of NaISA concentrations ranging from approximately 0.0001 to 0.256?mol·dm^?3 and at fixed pH values of approximately 4.5 and 11.6 to determine the ISA complexes of Fe(III). The data were interpreted using the SIT model that included previously reported stability constants for $ {{\text{Fe(ISA}})_{n}}^{3 - n} $ (with n varying from 1 to 4) and Fe(III)?COH complexes, and the solubility product for Fe(OH)₃(s) along with the values for two additional complexes (Fe(OH)₂(ISA)(aq) and $ {\text{Fe(OH)}}_{ 3} ( {{\text{ISA}})_{2}}^{2 - } $ ) determined in this study. These extensive data provided a log₁₀ K ⁰ value of 1.55?±?0.38 for the reaction $ ({\text{Fe}}^{ 3+ } + {\text{ISA}}^{-} + 2 {\text{H}}_{ 2} {\text{O}} \rightleftarrows {\text{Fe(OH}})_{ 2} {\text{ISA(aq}}) + 2 {\text{H}}^{ + } ) $ and a value of ?3.27?±?0.32 for the reaction $ ({\text{Fe}}^{ 3+ } + 2 {\text{ISA}}^{-} + 3 {\text{H}}_{ 2} {\text{O}} \rightleftarrows {\text{Fe(OH)}}_{ 3} ( {\text{ISA}})_{2}^{2 - } + 3 {\text{H}}^{ + } ) $ and show that ISA forms strong complexes with Fe(III) which significantly increase the Fe(OH)₃(s) solubility at pH?<~12. Thermodynamic calculations show that competition of Fe(III) with tetravalent ions for ISA does not significantly affect the solubilities of tetravalent hydrous oxides (e.g., Th and Np(IV)) in ISA solutions.     

New mixed heteropolytungstates containing Ge(IV) or Sn(IV)

New mixed heteropolyanions with formulae XZW₁₁O₃₉(OH)^m?[X = Si, Ge, B, As(V), Ga, Co(II), Zn; Z = Ge(IV), Sn(IV)] and X₂′ZW₁₇O₆₁(OH)^7?[X′= As(V), P(V);Z = Ge(IV), Sn(IV)] were prepared. Crystal systems of the potassium salts were determined. The stability range of the anions is given in terms of the pH. The acids corresponding to the salts were obtained and their neutralization studied. Spectroscopic and polarographic reduction studies are reported.