Phase equilibria in water-alkali metal (ammonium) sulfate-Oxifos B systems

Solubility in the H₂O-(NH₄)₂SO₄ (Li₂SO₄, Na₂SO₄)-Oxifos B (potassium bis(alkylpolyoxyethylene) phosphate, [C _n H_{2n + 1}O(C₂H₄O) _m ]₂POOK, n = 8−10, m = 6) ternary systems at 25°C is reported. A two-phase liquid-liquid equilibrium in the systems is observed in a wide pH range (at inorganic acid concentrations of 2 to 10 mol/l). These separating systems are suggested for use in liquid-liquid extraction of metal ions.     

Phase formation in Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-K<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-MMoO<Subscript>4</Subscript> (M = Ca,Pb, Ba) systems and the crystal structure of α-KLiMoO<Subscript>4</Subscript>

Solid-phase interactions in Li₂MoO₄-K₂MoO₄-MMoO₄ (M = Ca, Pb, Ba) systems were studied, and the subsolidus regions of these systems were triangulated. The lead and barium systems were studied in a more detailed way to discover that, along KLiMoO₄-K₂M(MoO₄)₂ (M = Pb, Ba), KLiMoO₄-PbMoO₄, and Li₂MoO₄-K₂Ba(MoO₄)₂ quasi-binary sections, there are homogeneity regions reaching 6–11 mol % based on K₂M(MoO₄)₂ and lead molybdate. Triple molybdates are formed in none of the systems, which is verified by experiments on spontaneous crystallization from solution in melt. Crystallization experiments yielded crystals of potassium dimolybdate and simple and double molybdates from the boundary systems. The crystal structure was solved for a hexagonal KLiMoO₄ phase: (Na,K){ZnPO4}, a = 18.8838(7) Å, c = 8.9911(6)Å, Z = 24, space group P6₃, R = 0.065. The structure comprises a three-dimensional tridymite framework built by an alternation of corner-sharing LiO₄- and MoO₄ tetrahedra wherein voids are occupied by potassium cations.     

Über die Systeme AJ/CoJ2 und die kristallchemischen Beziehungen in der Gruppe der Doppelhalogenide AnCoX(n+2) mit X = Cl,Br, J [1]

The Systems AI/CoI₂ (A = Alkali Metal, Tl, Ag) and the Crystal Chemistry of the Double Halides A_nCoX_(n+2) with X = Cl, Br, I The systems AI/CoI₂ (A = Cs, Rb, K, Tl, Na, Ag) were investigated by differencethermal analysis. The systems of NaI and AgI are found to be eutectical. A compound A₂CoI₄ always exists in the other systems. Cs₂CoI₄ crystallizes in the β-K₂SO₄ type with a coordination number (C.N.) for Cs equal to 9/10. Results obtained with single crystal technique reveal for the first time that among the double halides Rb₂CoI₄ is of the monoclinic Sr₂GeS₄ type (C. N. for Rb = 6(+2)). The compounds K₂CoJ₄, Tl₂CoJ₄, T-K₂CoBr₄, and T-Tl₂CoBr₄ are isotypic. Both structure groups are characterized by isolated CoX₄^2? tetrahedra. Reflectance spectra and magnetic susceptibilities can be explained on the basis of crystal field theory. – Our results close presently existing gaps in the knowledge on systems of CoBr₂ and CoCl₂ too.     

Phase diagrams of the SrEr2S4-SrLn2S4 (Ln = Nd, Dy, Yb) systems

The phase diagrams of the SrEr₂S₄-SrLn₂S₄ (Ln = Nd, Dy, Yb) systems were constructed, and the diagrams of the SrLn??₂S₄-SrLn??₂S₄ (Ln??, Ln?? = La-Lu) systems were predicted. The diagram of the SrEr₂S₄-SrNd₂S₄ system is of the eutectic type. The diagrams of the SrEr₂S₄-SrDy₂S₄ and SrEr₂S₄-SrYb₂S₄ systems involve the formation of a continuous series of solid solutions with the rhombic structure of the CaFe₂O₄.     

Five-component reciprocal systems Na,K∥Cl,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript> and Na,K∥F,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript>

Five-component reciprocal systems Na,K∥Cl,CO₃,MoO₄,WO₄ and Na,K∥F,CO₃,MO₄,WO₄ have been studied by differential thermal analysis (DTA) and X-ray powder diffraction (XPD). The systems have been triangulated to phase simplexes. The main reciprocal and complex-formation reactions have been revealed. The stability of [Na,K]₂CO₃, Na₂[Mo,W]O₄, and K₂[Mo,W]O₄ binary solid solutions and the nonexistence of quintuple invariant points in the title systems have been verified.     

Rotational isomerism inbis carbene MOL4 complexes: A theoretical study

LCAO-MO-SCF calculations are reported for the different stereoisomers of the Mo(CO)₄(CH₂)₂ and Mo(CO)₄[C(NH₂)₂]₂ systems. The substitution of the hydrogen atoms by the amino groups in the carbene ligands leads to an almost zero rotational barrier. Steric interactions are therefore expected to govern the barrier for diaminocarbene ligands which are more bulky than C(NH₂)₂. The rotational isomerism in thesebis carbene MoL₄ systems is also discussed in connection with the isolobal analogy between CH₂ and C₂H₄.     

Double molybdates of rare earth elements and zirconium

The results of the study of Ln₂(MoO₄)3—Zr(MoO₄)₂ molybdate systems, which made it possible to obtain new double molybdates, are summarized. The specific features of phase formation in double salt systems were determined and the formation of phases with the compositions given by three formulas Ln₂Zr₃(MoO₄)₉ (Ln = La—Tb), Ln₂Zr₂(MoO₄)₇ (Ln = Sm—Y), and Ln₂Zr(MoO₄)₅ (Ln = Tb—Lu) was established. Phase diagrams of the systems were constructed and the interrelation between the composition and the structure of the obtained phases was determined; in addition, crystallographic, thermal, and dielectric characteristics of the obtained compounds were studied.     

Metastable phase equilibria in the systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O at 308.15 K

Experimental studies on the metastable solubilities and physicochemical properties (density and refractive index) in the ternary systems K₂SO₄ + K₂B₄O₇ + H₂O and KCl + K₂B₄O₇ + H₂O at 308.15 K were determined with the method of isothermal evaporation. According to the experimental results, the phase diagrams of the two ternary systems were plotted. In the phase diagrams, there are both two isotherm evaporation curves, one eutectic point corresponding to K₂SO₄ + K₂B₄O₇ · 4H₂O, and KCl + K₂B₄O₇ · 4H₂O, respectively. Both of the ternary systems belong to a simple eutectic type, and neither double salts nor solid solutions formed in the ternary systems. A comparison of the stable and metastable phase diagrams of the ternary systems K₂SO₄ + K₂B₄O₇ + H₂O and KCl + K₂B₄O₇ + H₂O shows that the supersaturated phenomenon of potassium borate tetrahydrate is significant and easier to appear the metastable behavior.     

Phase equilibria in quasi-binary sections of the Tl-Sn-S system

Phase equilibria in quasi-binary sections of the Tl-Sn-S system: (I) Tl₄SnS₄-SnS, (II) Tl₂SnS₃-SnS, (III) S-Tl₄SnS₄, (IV) S-Tl₂SnS₃, (V) Tl-SnS, and (VI) Tl₂S-SnS were studied by differential thermal analysis and X-ray powder diffraction. It was found that systems I and II are characterized by the eutectic type of interaction, the phase diagrams of systems III and IV are of the eutectic type with a degenerate eutectic at the sulfur melting point, and the phase diagram of system V is of the fourth type according to Roozeboom. Phase equilibria in system VI were specified.     

Phase diagrams of (R4N)2[Nd(NO3)5]-carbon tetrachloride-n-octanol (n-butanol, n-decanol, cyclohexanol) liquid ternary systems at various temperatures

Phase diagrams are studied for (R₄N)₂[Nd(NO₃)₅]-CCl₄ n-octanol (n-butanol, n-decanol, cyclohexanol) ternary liquid systems, where R₄N⁺ stands for trialkylbenzylammonium, at T = 298.15–333.15 K. The (R₄N)₂[Nd(NO₃)₅]-CCl₄ binary system at all temperatures is a two-phase liquid. One phase (phase I) is almost neat carbon tetrachloride; the other (phase II) is enriched in (R₄N)₂[Nd(NO₃)₅]. The CCl₄ solubility in phase II increases with rising temperature. The liquid ternary systems are characterized by homogeneous and two-phase liquid solution fields. One phase is enriched in (R₄N)₂[Nd(NO₃)₅] and n-octanol (n-butanol, n-decanol, cyclohexanol) and the other in CCl₄. Miscibility fields in the ternary liquid systems narrow with rising temperature.     

Solubility in K+-Na+-Mg 4 2− aqueous solution at T = 298.15 K

In the salt solubility predictions for K⁺-Na⁺-Mg ₄ ^2? aqueous solution the treatment of thermodynamic data of three-component systems at T = 298.15 K involved the application of the Extended Pitzer’s ion-interaction model for the pure and mixed electrolyte solutions and criteria of phase equilibrium. Osmotic coefficients data of three-component systems were revised according to recently published parameters of the solutions NaCl(aq) and KCl(aq) that served as reference standards in isopiestic measurements. Parameters of the extended ion-interaction model of K₂SO₄(aq) are determined by treatment of experimental and predicted values of osmotic coefficient in supersaturated region obtained by the Zdanovskii-Stokes-Robinson rule. Results of salt solubility prediction were compared to experimental solubility data from literature. The agreement between calculated and experimental solubility data in the systems K₂SO₄ + MgSO₄ + H₂O, Na₂SO₄ + MgSO₄ + H₂O, and Na₂SO₄ + K₂SO₄ + H₂O at T = 298.15 K, was excellent.     

Phase formation in the systems Rb2MoO4-BaMoO4-R2(MoO4)3, R = Nd,Sm, Eu,Gd

Phase formation in the subsolidus area of the systems Rb₂MoO₄-BaMoO₄-R₂(MoO₄)₃ was studied by the methods of X-ray and differential-thermal analysis. In these systems ternary molybdates RbBaR(MoO₄)₃ crystallizing in the monoclinic crystal system (space group P2_1/n ) are formed. Their crystallographic parameters were calculated, and temperature dependences of the electrical conduction, dielectric permeability, and dielectric loss tangent were studied.     

On the interaction of tetraethoxosilane with metal alkoxides: Sol-gel synthesis of alkaline-earth metal silicates

Physicochemical analyses (solubility method, conductometry, and IR spectroscopy) revealed no complex formation in M(OR)_n-Si(OR)₄-ROH systems (M = Na, Ba, Al; R = Et, Prⁱ), unlike in the systems containing alkoxides of two metals. IR and NMR spectroscopy showed that Si(OR)₄ became reactive only due to microhydrolysis, which is accompanied most likely by the formation of intermediates (asymmetric molecules [Si(OH)_n(OR)_{4 ? n} ]). The hydrolysis was studied for model systems M(OEt)₂ ? si(OEt)₄ (M = Ba, Ca), and conditions for the synthesis of silicates were optimized.     

Interplay between Metal⋅⋅⋅π Interactions and Hydrogen Bonds: Some Unusual Synergetic Effects of Coinage Metals and Substituents

The ternary systems of C₂H₄ (C₂H₂ or C₆H₆)‐MCN‐HF (M=Cu, Ag, Au) and the respective binary systems were investigated to study the interplay between metal???π interactions and hydrogen bonds. The metal???π interactions in C₂H₄‐MCN become stronger with the irregular order Ag<Cu<Au, while the hydrogen bonds in MCN‐HF become weaker following the same order. The metal???π interactions are weakened as the H atoms in the π system are replaced with electron‐withdrawing groups and enhanced by electron‐donating groups. Type 1 of these ternary systems, in which MCN acts as Lewis base and acid simultaneously, is more stable than type 2, in which C₂H₄ acts as a double Lewis base. Negative cooperativity is present in type 2 ternary systems with a weakening of the metal???π interactions and the hydrogen bonds. Positive cooperativity is found in type 1 ternary systems with an enhancement of the metal???π interactions and the hydrogen bonds, except for C₂(CN)₄‐AuCN‐HF‐1. The weaker metal???π interaction in C₆H₆‐AuCN has a greater enhancing effect on the hydrogen bond in AuCN‐HF than those in C₂H₄‐AuCN and C₂H₂‐AuCN. These synergetic effects were analyzed with the natural bond orbital and energy decomposition.     

NO donors cis-[Ru(bpy)2(L)NO] and [Fe(CN)4(L)NO] complexes immobilized on modified mesoporous silica spheres

The reaction of [Ru(bpy)₂Cl₂] and Na₂[Fe(CN)₄(dmso)₂] complexes with isonicotinic acid immobilized on silica spheres (Si-ATPS-ISN) followed by a NO bubbling produced Si-ATPS-ISN-[Ru(bpy)₂(NO)] (system I) and Si-ATPS-ISN-[Fe(CN)₄(NO)] (system II). The characterization of these systems was carried out by UV–Vis, FTIR spectroscopy and electrochemical techniques. As judged by the FTIR data, the nitric oxide ligand has an NO⁺ character in both systems (ν(NO⁺): 1938 cm⁻¹). The NO release, which was monitored by means of FTIR, electrochemistry, and NO sensor electrode, was observed for both systems upon white light irradiation and chemical reduction by cysteine. These results indicated that the system (II) presents a higher potential for controlled NO release. The characterization (FTIR and UV–Vis) of the systems after the NO release suggested the formation of the aqua systems ATPS-ISN-[Ru(bpy)₂(OH₂)] and ATPS-ISN-[Ru(bpy)₂(OH₂)].     

Monomer-isomerization polymerization. XVI. Monomer-isomerization polymerization of methylpentenes with Ziegler-Natta catalyst

The polymerizations of 4-methyl-1-pentene(4M1P), 4-methyl-2-pentene (4M2P), 2-methyl-2-pentene (2M2P), and 2-methyl-1-pentene (2M1P) with Ziegler-Natta catalyst have been investigated. Both 4M1P and 4M2P were found to polymerize with TiCl₃–(C₂H₅)Al catalyst to give high molecular weight poly(4M1P), while 2M2P and 2M1P did not give polymers with 4M1P units. However, when the polymerizations of 2M1P and 2M2P were carried out with ternary catalyst systems, TiCl₃–(C₂H₅)AlCl–(PPh₃)₂PdCl₂ and TiCl₃–(C₂H₅)AlCl–Ni(SCN)₂ polymers with 4M1P units were obtained in low yield. It was concluded that these four methylpentenes could polymerize with the monomer-isomerization polymerization mechanism to poly(4M1P). The results of the observed isomer distribution of methylpentenes recovered, and the rate of polymerization of four methylpentenes suggest that the isomerization from 2M1P to 4M1P with the above ternary catalyst systems might proceed via a direct one-step isomerization mechanism.     

Phase formation in the systems Ag2MoO4-MO-MoO3 (M=Ca, Sr, Ba, Pb, Cd, Ni, Co, Mn) and crystal structures of Ag2M2(MoO4)3 (M=Co, Mn)

Phase equilibria in the systems Ag₂MoO₄-MMoO₄ (M=Ca, Sr, Ba, Pb, Ni, Co, Mn) and subsolidus phase relations in the systems Ag₂MoO₄-MO-MoO₃ (M=Ca, Pb, Cd, Mn, Co, Ni) were investigated using XRD and thermal analysis. The systems Ag₂MoO₄-MMoO₄ (M=Ca, Sr, Ba, Pb, Ni) belong to the simple eutectic type whereas in the systems Ag₂MoO₄-MMoO₄ (M=Co, Mn) incongruently melting Ag₂M₂(MoO₄)₃ (M=Co, Mn) were formed. In the ternary oxide systems studied no other compounds were found. Low-temperature LT-Ag₂Mn₂(MoO₄)₃ reversibly converts into the high-temperature form of a similar structure at 450-500°C. The single crystals of Ag₂Co₂(MoO₄)₃ and LT-Ag₂Mn₂(MoO₄)₃ were grown and their structures determined (space group , Z=2; lattice parameters are a=6.989(1) Å, b=8.738(2) Å, c=10.295(2) Å, α=107.67(2)°, β=105.28(2)°, γ=103.87(2)° and a=7.093(1) Å, b=8.878(2) Å, c=10.415(2) Å, α=106.86(2)°, β=105.84(2)°, γ=103.77(2)°, respectively) and refined to R(F)=0.0313 and 0.0368, respectively. The both compounds are isotypical to Ag₂Zn₂(MoO₄)₃ and contain mixed frameworks of MoO₄ tetrahedra and pairs of M²⁺O₆ octahedra sharing common edges. The Ag⁺ ions are disordered and located in the voids forming infinite channels running along the a direction. The peculiarities of the silver disorder in the structures of Ag₂M₂(MoO₄)₃ (M=Zn, Mg, Co, Mn) are discussed as well as their relations with analogous sodium-containing compounds of the structural family of Na₂Mg₅(MoO₄)₆. The phase transitions in Ag₂M₂(MoO₄)₃ (M=Mg, Mn) of distortive or order-disorder type are suggested to have superionic character.     

Propene polymerization with Ziegler-type catalysts formed from Me2Si(Ind)2ZrMe2 and cation-generating reagents

Kinetic and polymer analytical results obtained with the systems Me₂Si(Ind)₂ZrMe₂/[B(C₆F₄Si(i-Pr)₃)₄]⁻ [(C₆H₅)₃C]⁺ (2) and Me₂Si(Ind)₂ZrMe₂/[B(C₆F₅)₄]⁻ [(C₆H₅)₃C]⁺ (3) in olefin polymerizations are compared (Me: methyl; Ind: indenyl). Both systems show that the polymerization rate increases with increasing metallocene concentration in a surplus due to the formation of binuclear species. The expected influence of increasing cation-anion distance on the stereo-errors of the poly(propylene)s when changing from system 3 into system 2 could not be detected.     

Phase equilibria in the water-alkali metal or ammonium sulfate-synthanol systems

Solubility was studied for the first time in ternary aqueous phase-separating systems containing synthanol DS-10 or ALM-10 (polyethylene glycol monoalkyl ethers based on primary fatty alcohols, C _n H_{2n ? 1}O(C₂H₄O) _m H, where m = 8–10 and n = 10–18 (synthanol DS-10) or 12–14 (synthanol ALM-10)) and inorganic salt (NH₄)₂SO₄, Na₂SO₄, or Li₂SO₄ at 25°C. The boundaries of two-phase liquid equilibrium regions were determined. It was proposed to use the studied phase-separating systems for liquid extraction of metal ions.