Solubility of Zr(OH)<Subscript>4</Subscript>(am) and the Formation of Zr(IV) Carbonate Complexes in Carbonate Solutions Containing 0.1–5.0 mol·dm<Superscript>−3</Superscript> NaNO<Subscript>3</Subscript>

The solubility of amorphous zirconium hydroxide [Zr(OH)₄(am)] was investigated in carbonate solutions containing various concentrations of sodium nitrate. The observed dependences of Zr(IV) solubility on the hydrogen ion concentration (pH_c) and carbonate concentration suggested the formation of \( {\text{Zr}}({{\text{CO}}}_{3} )_{4}^{4 - } \), \( {\text{Zr}}({{\text{CO}}}_{3} )_{5}^{6 - } \), and \( {\text{Zr(OH)}}_{ 2} ( {{\text{CO}}}_{3} )_{2}^{2 - } \) as the dominant species in the neutral to weakly alkaline pH regions. The solubility of Zr(IV) at certain pH_c values and carbonate concentrations was observed to increase slightly with increasing ionic strength, while the solid phase was determined to be Zr(OH)₄(am) at all ionic strengths by using thermal analysis. By applying the specific ion interaction theory, the solubility data at different pH_cs, carbonate concentrations, and ionic strengths were analyzed to determine the formation constants of the Zr(IV) carbonate complexes and their ion interaction coefficients. The obtained values explain well the solubility data, which are discussed in comparison with those of analogous tetravalent actinide carbonates.     

The Examination of the Activity Coefficients of Cu(II) Complexes with OH<Superscript>−</Superscript> and Cl<Superscript>−</Superscript> in NaClO<Subscript>4</Subscript> Using Pitzer Equations: Application to Other Divalent Cations

The stability constants for the hydrolysis of Cu(II) and formation of chloride complexes in NaClO₄ solution, at 25 °C, have been examined using the Pitzer equations. The calculated activity coefficients of CuOH⁺, Cu(OH)₂, Cu₂(OH)³⁺, Cu₂(OH)₂²⁺, CuCl⁺ and CuCl₂ have been used to determine the Pitzer parameter (β _i ⁽⁰⁾, β _i ⁽¹⁾, and C _i ) for these complexes. These parameters yield values for the hydrolysis constants (log ₁₀ β ₁^*, log ₁₀ β ₂^*, log ₁₀ β _2,1^* and log ₁₀ β _2,2^*) and the formation of the chloride complexes (log ₁₀ β _CuCl^* and that agree with the experimental measurements, respectively to ±0.01,±0.02,±0.03,±0.06,±0.03 and ±0.07. The stability constants for the hydrolysis and chloride complexes of Cu(II) were found to be related to those of other divalent metals over a wide range of ionic strength. This has allowed us to use the calculated Pitzer parameters for copper complexes to model the stability constants and activity coefficients of hydroxide and chloride complexes of other divalent metals. The applicability of the Pitzer Cu(II) model to the ionic strength dependence of hydrolysis of zinc and cadmium is presented. The resulting thermodynamic hydroxide and chloride constants for zinc are and . For cadmium the thermodynamic hydrolysis constants are and . The Cu(II) model allows one to determine the stability of other divalent metal complexes over a wide range of concentration when little experimental data are available. More reliable stepwise stability constants for divalent metals are needed to test the linearity found for the chloro complexes.     

The Influence of Ionic Strength on Yttrium and Rare Earth Element Complexation by Fluoride Ions in NaClO<Subscript>4</Subscript>, NaNO<Subscript>3</Subscript> and NaCl Solutions at 25 °C

Stability constants of the form _F β ₁(M)=[MF²⁺][M³⁺]⁻¹[F⁻]⁻¹ (where [MF²⁺] represents the concentration of a yttrium or a rare earth element (YREE) complex, [M³⁺] is the free YREE ion concentration, and [F⁻] is the free fluoride ion concentration) were determined by direct potentiometry in NaNO₃ and NaCl solutions. The patterns of log_{10  F} β ₁(M) in NaNO₃ and NaCl solutions very closely resemble stability constant patterns obtained previously in NaClO₄. For a given YREE, stability constants obtained in NaClO₄ were similar to, but consistently larger than _F β ₁(M) values obtained in NaNO₃ which, in turn, were larger than formation constants obtained in NaCl. Stability constants for formation of nitrate and chloride complexes ( and _Cl β ₁(M)=[MCl²⁺][M³⁺]⁻¹[Cl⁻]⁻¹) derived from _F β ₁(M) data exhibited ionic strength dependencies generally similar to those of _F β ₁(M). However, in contrast to the somewhat complex pattern obtained for _F β ₁(M) across the fifteen member YREE series, no patterns were observed for nitrate and chloride complexation constants: neither nor _Cl β ₁(M) showed discernable variations across the suite of YREEs. Nitrate and chloride formation constants at 25 °C and zero ionic strength were estimated as log₁₀  and log_{10  Cl} β ₁^o(M)=0.71±0.05. Although these constants are identical within experimental uncertainty, the distinct ionic strength dependencies of and _Cl β ₁(M) produced larger differences in the two stability constants with increasing ionic strength whereby _Cl β ₁(M) was uniformly larger than .     

The Hydrolysis of AuCl<Stack><Subscript>4</Subscript><Superscript>−</Superscript></Stack> and the Stability of Aquachlorohydroxocomplexes of Gold(III) in Aqueous Solution

The equilibria AuCl₄⁻+jOH⁻+kH₂O⇌AuCl_4−j−k (OH) _j (H₂O) _k ^k−1+(j+k)Cl⁻, β _jk (0≤j,k≤4) have been studied spectrophotometrically at 20 °C in aqueous solution. For I=2 mol⋅dm⁻³(HClO₄) the conventional constants, β _i ^*, of the equilibria, Au^*+iCl⁻ ⇌AuCl _i ^*, are equal to log ₁₀ β ₁^*=(6.98±0.08); log ₁₀ β ₂^*=(13.42±0.05); log ₁₀ β ₃^*=(19.19±0.09); and log ₁₀ β ₄^*=(24.49±0.07), where [AuCl _i ^*]=∑[AuCl _i (OH) _j (H₂O)_4−i−j ] at i=const. The hydrolysis and other transformations of AuCl₄⁻ in aqueous solution are discussed. On the basis of new and known data, a full set of equilibrium constants, β _jk , or their estimates has been obtained.     

Fragmentation Reactions of b<Subscript>5</Subscript> and a<Subscript>5</Subscript> Ions Containing Proline—The Structures of a<Subscript>5</Subscript> Ions

A detailed study has been made of the b₅ and a₅ ions derived from the amides H-Ala-Ala-Ala-Ala-Pro-NH₂, H-Ala-Ala-Ala-Pro-Ala-NH₂, and H-Ala-Ala-Pro-Ala-Ala-NH₂. From quasi-MS³ experiments it is shown that the product ion mass spectra of the three b₅ ions are essentially identical, indicating macrocyclization/reopening to produce a common mixture of intermediates prior to fragmentation. This is in agreement with numerous recent studies of sequence scrambling in b ions. By contrast, the product ion mass spectra for the a₅ ions show substantial differences, indicating significant differences in the mixture of structures undergoing fragmentation for these three species. The results are interpreted in terms of a mixture of classical substituted iminium ions as well as protonated C-terminal amides formed by cyclization/rearrangement as reported recently for a₄ ions (Bythell, Maître , Paizs, J . Am. Chem. Soc. 2010, 132, 14761–14779). Novel fragment ions observed upon fragmentation of the a₅ ions are protonated H-Pro-NH₂ and H-Pro-Ala-NH₂ which arise by fragmentation of the amides. The observation of these products provides strong experimental evidence for the cyclization/rearrangement reaction to form amides and shows that it also applies to a₅ ions.     

The effect of Me<Subscript>4</Subscript>NBr,Et<Subscript>4</Subscript>NBr,Bu<Subscript>4</Subscript>NBr,and (EtOH)<Subscript>3</Subscript>EtNBr on the Temperature of Maximum Density of Water

The densities of aqueous solutions of Me₄NBr, Et₄NBr, Bu₄NBr, and Et(OH)₃EtNBr were measured in the concentration range 0.002 to 0.05 mol⋅kg⁻¹. The temperature of the determinations ranged from 275.15 to 279.15 K in 0.5 K steps, and the uncertainty of the densities was around ±1×10⁻⁶ g⋅cm⁻³. Eleven concentrations were used for each of the salts. It was found that all the solutes follow Despretz’ law. The absolute value of the Despretz’s constants increases with increasing number of carbon atoms in the cation, except for Et(OH)₃EtNBr which has the highest value. The ionic contributions to the Despretz’s constants were calculated. The volumetric data obtained allows the calculation proposed by Kalgud and Pokale. The effective ionic radii were calculated using a semi-empirical equation, as proposed previously by several workers. The nonlinearity of the plot of the ionic Despretz constants versus effective ionic radius is confirmed.     

Crystal structure of a novel binuclear Cu(II) complex Cu<Subscript>2</Subscript>[(Dmbiim)<Subscript>4</Subscript>H<Subscript>2</Subscript>O](ClO<Subscript>4</Subscript>)<Subscript>4</Subscript>·3H<Subscript>2</Subscript>O

A novel complex, Cu₂[(Dmbiim)₄H₂O](ClO₄)₄·₃H₂O (Dmbiim = 1.1′-dimethyl-2.2′-biimida-zole), has been synthesized and studied by X-ray crystallography. Crystal data for CuO₉N₈C₁₆Cl₂H₂₂: a = 10.160(2) Å, b = 12.991(3) Å, c = 20.646(4) Å, β = 101.443(3)°, space group P2(1)/c, Z = 4, d _calc = 1.504 g/cm³, R = 0.0718. The crystal structure reveals that the complex is cage-shaped, with two Cu ions bridged by Dmbiim and each Cu ion chelated by the oxygen atom of water and four nitrogen atoms of Dmbiim.     

Raman and Infrared Spectroscopic Investigation of Speciation in BeSO<Subscript>4</Subscript>(aq)

Measurements have been made of the Raman spectra of aqueous solutions of Be(ClO₄)₂, BeCl₂, (NH₄)₂SO₄ and BeSO₄ to 50 cm⁻¹. In some cases low concentrations (0.000770 mol⋅kg⁻¹) have been used and two temperatures (23 and 40 °C) were studied. In BeSO₄(aq), the ν ₁-SO₄^2-\mathrm{SO}_{4}^{2-} mode at 980 cm⁻¹ broadens with increasing concentration and shifts to higher wavenumbers. At the same time, a band at 1014 cm⁻¹ is detectable with this mode being assigned to [BeOSO₃], an inner-sphere complex (ISC). Confirmation of this assignment is provided by the simultaneous appearance of stretching bands for the Be²⁺-OSO₃^2-\mathrm{Be}^{2+}\mbox{-}\mathrm{OSO}_{3}^{2-} bond of the complex at 240 cm⁻¹ and for the BeO₄ skeleton mode of the [(H₂O)₃BeOSO₃] unit at 498 cm⁻¹. The ISC concentration increases with higher temperatures. The similarity of the n₁-SO₄^2-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} Raman bands for BeSO₄ in H₂O and D₂O is further strong evidence for formation of an ISC. After subtraction of the ISC component at 1014 cm⁻¹, the n₁-SO₄^2-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} band in BeSO₄(aq) showed systematic differences from that in (NH₄)₂SO₄(aq). This is consistent with a n₁-SO₄^2-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} mode at 982.7 cm⁻¹ that can be assigned to the occurrence of an outer-sphere complex ion (OSCs). These observations are shown to be in agreement with results derived from previous relaxation measurements. Infrared spectroscopic data show features that are also consistent with a beryllium sulfato complex such as the appearance of a broad and weak n₁-SO₄^2-\nu_{1}\mbox{-}\mathrm{SO}_{4}^{2-} mode at ∼1014 cm⁻¹, normally infrared forbidden, and a broad and asymmetric n₃-SO₄^2-\nu_{3}\mbox{-}\mathrm{SO}_{4}^{2-} band contour which could be fitted with four band components (including n₃-SO₄^2-(aq)\nu_{3}\mbox{-}\mathrm{SO}_{4}^{2-}(\mathrm{aq})). The formation of ISCs in BeSO₄(aq) is much more pronounced than in the similar MgSO₄(aq) system studied recently.     

Synthesis and crystal structure of supramolecular compounds of cucurbituryl with the chalcocyanide cluster complex [Re<Subscript>4</Subscript>Te<Subscript>4</Subscript>(CN)<Subscript>12</Subscript>]<Superscript>4−</Superscript> and a manganese(II) aqua complex

Supramolecular compounds [Mn(H₂O)₄(C₃₆H₃₆N₂₄O₁₂)]₂[Re₄Te₄(CN)₁₂]·12.5H₂O (1), (H₃O)₂[{Mn(H₂O)₄ (C₃₆H₃₆N₂₄O₁₂)}{Mn(H₂O)₄} ₂{Re₄Te₄(CN)₁₂}₂]·3.5H₂O (2) and [{Mn(H₂O)₃Cl} ₂(C₃₆H₃₆N₂₄O₁₂)]Cl₂·6H₂O (3) were obtained by crystallization at room temperature from water solutions containing macrocyclic cavitand cucurbituryl (C₃₆H₃₆N₂₄O₁₂), aqua complex of manganese(II) (1–3) and chalcocyanide cluster complex [Re₄Te₄(CN)₁₂]^4? (1, 2). From XRD analysis, the cucurbituryl molecule is bound with one (1, 2) or two atoms of manganese (3) through oxygen atoms of carbonyl groups. Compound 2 has a chain structure where cluster complexes of rhenium are linked through bridge manganese atoms into a polymeric ribbon. Compounds 1 and 3 have the island-like type of structure.     

Phase Transitions and Ionic Mobility in Solid Solutions in the System (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>ZrF<Subscript>6</Subscript>–InF<Subscript>3</Subscript>

¹H and ¹⁹F NMR, XRD, and DTA methods are used to study thermal properties, ion mobility, and phase transitions (PT) in solid solutions obtained by doping anion-cationic conductor (NH₄)₂ZrF₆ with indium trifluoride. The types of ionic mobility are determined in the fluorine and ammonium sublattices of synthesized solid solutions at 150–450 K, their activation energies are estimated. A phase transition associated with formation of high-temperature modifications is registered at 400–413 K; ionic mobility in these modifications is mostly due to the diffusion of fluorine and ammonium ions.     

Complexes of some divalent metals with alcoxy-NNO-azoxy compounds: Crystal and molecular structures of С<Subscript>5</Subscript>H<Subscript>12</Subscript>N<Subscript>4</Subscript>O<Subscript>6</Subscript>

Seven new metal complexes with alcoxy-NNO-azoxy compounds were synthesized and isolated in a crystalline state. The crystal and molecular structures of С₅H₁₂N₄O₆ were established by X-ray diffraction. Some spectral criteria of coordination were determined, and the complexation processes in solutions were studied.     

Reaction of [Pd(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>]Cl<Subscript>2</Subscript> with NH<Subscript>4</Subscript>ReO<Subscript>4</Subscript> in alkaline water solution at 190°C (autoclave process)

A reaction of tetraammine palladium(II) chloride with ammonium perrhenate in aqueous alkaline solution in the autoclave conditions was studied. The possible routes of the palladium and rhenium reduction with ammonia were suggested.     

Synthesis and structural characterization of a novel tetranuclear Cu(II) complex: [Cu<Subscript>4</Subscript>L<Subscript>2</Subscript>(pic)<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>]·2H<Subscript>2</Subscript>O

A novel Salen-type bisoxime ligand, 6,6′-dimethoxy-2,2′-[(1,4-butylene)dioxybis(nitrilomethylidyne)]diphenol (H₂L) and its tetranuclear Cu(II) complex, [Cu₄L₂(pic)₄(H₂O)₂]·2H₂O, have been synthesized and characterized by elemental analyses, IR, TG-DTA and ¹H-NMR etc. The X-ray crystal structure of the complex reveals that formation of a tetranuclear structure, which consists of four copper(II) atoms, two pentadentate L²⁻units, four picratols, two coordinated water molecules and two crystallizing water molecules. Around four copper ions are all octahedral geometries. It was demonstrated that the picratols in the tetranuclear copper(II) complex show a novel tridentate coordination mode.     

Copper(II) oxalate obtained through the reaction of 1,2-ethanediol with Cu(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>·3H<Subscript>2</Subscript>O

The paper presents the experimental results of the structural investigations and thermal analysis of copper(II) oxalate, a polynuclear coordination compound, obtained by a new method, through the reaction of 1,2-ethanediol with Cu(NO₃)₂·3H₂O. The reaction between 1,2-ethanediol and Cu(NO₃)₂·3H₂O occurs, under some working conditions, with the oxidation of 1,2-ethanediol to the oxalate anion (L). The synthesized polynuclear coordination compound, [CuL·0.3H₂O]_n, was characterized by chemical analysis, electronic and vibrational spectra and thermal analysis. The thermal properties of the polynuclear coordination compound have been investigated by TG, DTG and DSC. The obtained decomposition product is CuO. Powder XRD (X-ray diffraction), IR spectroscopy and TEM (transmission electron microscopy) were used to characterize the composition, the crystalline structure and the surface morphology of the copper oxide obtained through thermolysis. The thermal conversion product, copper(II) oxide, has a microporous structure with a large specific area.     

π-Complex of Cu(I) Chloride with 1-Allyloxybenzotriazole CuCl · C<Subscript>6</Subscript>H<Subscript>4</Subscript>N<Subscript>3</Subscript>(OC<Subscript>3</Subscript>H<Subscript>5</Subscript>)

Single crystals of CuCl · C₆H₄N₃(OC₃H₅)(I) are synthesized by ac electrochemical method from Cu(II) chloride and 1-allyloxybenzotriazole in ethanol solution and their unit cell parameters are determined: space group P2₁/a a=11.583(4) , b=11.443(7) , c=8.620(4) , =108.77(3)°, V=1082(2) ³, R(F)=0.0366, R _w (F)=0.0396 for 1095 reflections. In the structure of -complex I, inorganic fragment Cu₂Cl₂ forms centrocymmetric parallelogram. A molecule of 1-allyloxybenzotriazole acts as a bridge, which is bonded to the Cu atoms of two inorganic dimers through the C=C bond of the allyl group and to the N atom of a triazole ring. Owing to this bridging function, the ligand molecules form zigzag organometallic layers. The trigonal-pyramidal coordination sphere of a metal atom includes two Cl atoms and the C=C group. The structural motif of complex I significantly differs from that of the previously studied 2CuCl · C₆H₄N₃(OC₃H₅) and resembles the motif of a bromide analog Cu₂Br₂ · [C₆H₄N₃(OC₃H₅)]₂.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 364–369.Original Russian Text Copyright © 2005 by Goreshnik, Myskiv.     

The Determining Role of the (HF<Subscript>2</Subscript>)<Superscript>–</Superscript> Ion in the Formation of Pores in Silicon in Its Electrochemical Etching with Hydrofluoric Acid Solutions

A model of the chemical interaction of Si with the (HF₂)^– ion was propsoed to explain some experimental data on the formation of porous silicon.     

Synthesis of nanopowders and physicochemical properties of ceramic matrices of the LaPO<Subscript>4</Subscript>–YPO<Subscript>4</Subscript>–(H<Subscript>2</Subscript>O) and LaPO<Subscript>4</Subscript>–HoPO<Subscript>4</Subscript>–(H<Subscript>2</Subscript>O) systems

Sol-gel method was used to synthesize nanosize powders in the LaPO₄–YPO₄–(H₂O) and LaPO₄–HoPO₄–(H₂O) systems. Dense ceramic samples with high microhardness (up to 25 GPa) were formed from these powders by sintering at temperatures of up to 1600°C. The isomorphic capacity of the monoclinic LaPO₄ matrix for the second component (yttrium or holmium) simulating radioactive nuclides of the actinide-rare-earth fraction was found to be high. The composites are stable in aqueous solutions, which is indicated by the low concentration of lanthanum and yttrium ions during leaching test (~10^–7 g L^–1). The results obtained in the study can be used to develop new high-efficiency ceramic matrices for solidification of the actinide-rare-earth fraction of liquid wastes formed in processing of the spent nuclear fuel.     

Solubility and stability of (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>SO<Subscript>4</Subscript>·H<Subscript>2</Subscript>O<Subscript>2</Subscript> in organic and aqueous-organic media

Solubility and stability of (NH₄)₂SO₄·H₂O₂ in organic solvents (glycerol, ethylene glycol, TOSOL-A40 OM antifreeze), in mixtures of an organic solvent and water, and in pure water was studied. Crystallographic properties of the ammonium sulfate precipitating from aqueous-organic solvents and aqueous solutions in various time intervals and differing from ordinary (NH₄)₂SO₄ in solubility and one of crystallographic parameters were analyzed.     

Crystal structure and thermal properties of [Au(en)<Subscript>2</Subscript>]<Subscript>2</Subscript>[Cu(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>]<Subscript>3</Subscript>·8H<Subscript>2</Subscript>O

The crystal structure of a double complex salt of the composition [Au(en)₂]₂[Cu(C₂O₄)₂]₃·8H₂O (en = ethylenediamine) at 150 K is determined by single crystal X-ray diffraction. The crystal data for C₂₀H₄₈Au₂Cu₃N₈O₃₂ are: a = 9.1761(3) Å, b = 16.9749(6) Å, c = 13.4475(5) Å, β = 104.333(1)°, V = 2029.43(12) ų, P2₁/c space group, Z = 2, d _x = 2.450 g/cm³. It is demonstrated that the thermal decomposition of the double complex salt in a helium or hydrogen atmosphere affords the solid solution Au_0.4Cu_0.6.