Quasi-ternary system Tl<Subscript>2</Subscript>Se-AgTlSe-TlBiSe<Subscript>2</Subscript>

The quasi-ternary system Tl₂Se-AgTlSe-TlBiSe (A) has been investigated by DTA, X-ray powder diffraction, microstructural analysis, and microhardness measurements. Polythermal sections AgTlSe-TlBiSe₂, AgTlSe-Tl₉BiSe₆, [Ag_0.5Tl_1.5Se]-TlBiSe₂, Tl₂Se-AgBiSe₂ (0–50 mol % AgBiSe₂), an isothermal section at 500 K, and the projection of the liquidus surface of system A have been constructed. It has been shown that the quasi-binary join AgTlSe-Tl₉BiSe₆ divides system A into two subordinate triangles, namely, Tl₂Se-Tl₉BiSe₆-AgTlSe (B) and AgTlSe-Tl₉BiSe₆-TlBiSe₂ (C). The phase diagram of subsystem B involves a univariant eutectic equilibrium while subsystem C involves an invariant eutectic equilibrium. The ternary eutectic has the coordinates 650 K, 10 mol % TlBiSe₂, and 61 mol % AgTlSe. A continuous series of solid solutions (0–12 mol % AgTlSe) has been found along the Tl₂Se-Tl₉BiSe₆ bordering system. The homogeneity region of TlBiSe₂ extends to 5 mol %.     

Interaction in the systems TlBiSe<Subscript>2</Subscript>–Tl<Subscript>9</Subscript>BiSe<Subscript>6</Subscript>–PbSe and Tl<Subscript>9</Subscript>BiSe<Subscript>6</Subscript>–Tl<Subscript>4</Subscript>PbSe<Subscript>3</Subscript>–PbSe

Phase equilibria in the systems TlBiSe₂–Tl₉BiSe₆–PbSe and Tl₉BiSe₆–Tl₄PbSe₃–PbSe were studied by differential thermal, X-ray powder diffraction, and microstructural analyses. State diagrams of the quasi-binary sections Tl₉BiSe₆–Tl₄PbSe₃, TlBiSe₂–PbSe, and Tl₉BiSe₆–PbSe were constructed, and so were projections of liquidus surfaces and isothermal sections at 600 K for the secondary quasi-ternary systems TlBiSe₂–Tl₉BiSe₆–PbSe and Tl₄PbSe₃–Tl₉BiSe₆–PbSe. The coordinates of invariant points and the boundaries of solid solutions were determined.     

Phase equilibria in systems based on Tl4SnSe3 and Tl4SnSe4 ternary compounds

Phase equilibria in the Tl₄SnSe₃-Tl (I), Tl₄SnSe₃-Sn (II), Tl₄SnSe₄-SnSe (III), Tl₄SnSe{ia4}-TlSe (IV), and Tl₄SnSe₃-Tl₄SnSe₄ (V) systems have been studied by differential thermal analysis and power X-ray diffraction. Systems I–V have been found to have eutectic interactions. In systems I and II, width regions of solid solutions based on the ternary compound Tl₄SnSe₃ are formed.     

Ag2Se-AgTlSe-TlBiSe2 quasi-ternary system

Phase equilibria in the Ag-Tl-Bi-Se system in the region Ag₂Se-AgTlSe-TlBiSe₂ (I) have been investigated by DTA, X-ray powder diffraction analysis, microstructural analysis, and microhardness measurements. The Ag₂Se-TlBiSe₂, AgTlSe-AgBiSe₂ (0–50 mol % AgBiSe₂), and Ag₃TlSe₂-TlBiSe₂ polythermal sections and the projection of the liquidus surface have been constructed. It has been found that system I is quasi-ternary; it consists of the primary crystallization fields of the phases based on the Ag₂Se, TlBiSe₂, AgTlSe, Ag₃TlSe₂, and Ag₇TlSe₄ compounds. The system is characterized by peritectic and eutectic four-phase equilibria. The coordinates of the invariant points are the following: 690 K, 50 mol % Ag₂Se, 7 mol % TlBiSe₂ (P ₃); 658 K, 39 mol % Ag₂Se, 4 mol TlBiSe₂ (P ₄); and 650 K, 32 mol % Ag₂Se, 3.5 mol % TlBiSe₂ (E).     

Tl2S-Sb2S3-Bi2S3 quasi-ternary system

The Tl₂S-Sb₂S₃-Bi₂S₃ quasi-ternary system (system A) was studied using DTA, X- ray powder diffraction, microstructure examination, and microhardness measurements. TlSbS₂-Tl₄Bi₂S₅(TlBiS₂, Bi₂S₃), Sb₂S₃-TlBiS₂, Tl₃SbS₃-TlBiS₂(Bi₂S₃), and [TlSb_0.5Bi_0.5S₂]-Tl₂S isopleths; isothermal sections at 500 K; and liquidus surface projection of system A were constructed. Characteristic features of the title system are extensive fields of solid solutions extended along the TlSbS₂-TlBiS₂ quasi-binary section and a continuous solubility belt 1–2 mol % wide extended along the Sb₂S₃-Bi₂S₃ binary subsystem. Primary separation fields of phases and the types and coordinates of invariant and monovariant equilibria in system A were determined.     

Solvent extraction and spectrophotometric determination of uranium (VI)

Summary Solvent extraction of uranium-sodium diethyldithiocarbamate with ethylmethyl ketone and separation from titanium, zirconium, thorium, lanthanum and cerium has been described. It has been found that 11.75 to 47.00 mg of uranium can be extracted from a binary mixture containing 4.78 to 19.04 mg of titanium, 9.12 to 36.48 mg of zirconium, 116.0 to 460.0 mg of thorium, 6.95 to 27.8 mg of lanthanum or 7.06 to 28.24 mg of cerium at pH 3.0. The pH range between which the separations may be carried out successfully is 2.0 to 3.5. The following cations interfere in the separations: Cu^II, Fe^III, Co^II, Bi^III, Ni^II, Cr^VI, Te^IV, Se^IV, Ag^I, Hg^II, As^III, Sn^IV, Pb^IV, Cd^II, Mo^VI, Mn^II, V^V, Zn^II, In^III, Tl^I, W^VI, Os^VIII and Nb^V.

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Zusammenfassung Uran kann durch Extraktion als Diäthyldithiocarbamidat mit Methyläthylketon von Ti, Zr, Th, La oder Ce getrennt werden. Der günstigste pH-Bereich liegt zwischen 2,0 und 3,5. Die Trennungen wurden mit folgenden Mengen durchgeführt: U (11,75–47,00 mg); Ti (4,78 bis 19,04 mg), Zr (9,12–36,48 mg) Th (116,0–460,0 mg), La (6,95–27,8 mg), Ce (7,06–28,24 mg). Folgende Ionen verursachen Störungen: Cu^II, Fe^III, Co^II, Bi^III, Ni^II, Cr^VI, Te^IV, Se^IV, Ag^I, Hg^II, As^III, Sn^IV, Pb^IV, Cd^II, Mo^VI, Mn^II, V^VI, Zn^II, In^III, Tl^I, W^VI, Os^VIII sowie Nb^V.

     

Phase equilibria in the Ag2Te-PbTe-Bi2Te3 system

Phase equilibria in the Ag₂Te-PbTe-Bi₂Te₃ quasi-ternary system were studied by differential thermal analysis, X-ray powder diffraction, and measurements of microhardness and emf of concentration circuits with an Ag₄RbI₅ solid electrolyte. Some polythermal sections and isothermal (600 and 800 K) sections of the phase diagram, and also a projection of the liquidus surface were constructed. The primary crystallization fields of phases were determined, and the types and coordinates of invariant and monovariant equilibria were found. The system is characterized by the formation of a wide continuous band of high-temperature solid solutions (γ phase) with a cubic structure along the PbTe-AgBiTe₂ section. With decreasing temperature (T ≤ 715 K), AgBiTe₂ and γ solid solutions, close in composition to this compound, experience solid-phase decomposition to form Bi₂Te₃, ternary tetradymite-like phases of the PbTe-Bi₂Te₃ boundary system, and the low-temperature phase of Ag₂Te.     

Interactions and glass formation in the TlAs2Se4-Tl3As2Se3Te3 system

The TlAs₂Se₄-Tl₃As₂Se₃Te₃ system was studied using differential thermal analysis (DTA), powder X-ray diffraction, microstructure observation, and microhardness and density measurements. A phase diagram of the title system was constructed. This system is a quasi-binary join of the TlSe-As₂Se₃-As₂Te₃ quasi-ternary system. All alloys of the system under standard conditions are prepared in the glassy form. The system has a eutectic, which contains 50 mol % Tl₃As₂Se₃Te₃ and melts at 150°C. The TlAs₂Se₄-base solid solution in the system extends to 12 mol % Tl₃As₂Se₃Te₃, and Tl₃As₂Se₃Te₃-based solid solution extends to 20 mol % TlAs₂Se₄.     

Phase equilibria in the Cu-Bi-Se system and thermodynamic properties of copper selenobismuthates

The Cu-Bi-Se system was studied using DTA, X-ray powder diffraction, and electromotive force (e.m.f.) measurements in (−) Cu (solid)|Cu₄RbCl₃I₂ (solid)|(Cu in alloy) (solid) (+) concentration cells in the range 300–430 K. Polythermal sections and a 300-K isothermal section of the phase diagram are constructed, as well as a liquidus surface projection. The existence of ternary compounds CuBi₃Se₅, CuBiSe₂, and Cu₃BiSe₃ is verified, and phase fields involving them are established. Primary separation fields and the types and coordinates of invariant and monovariant equilibria are determined. E.m.f. data were used to calculate partial molar functions $ (\Delta \bar G,\Delta \bar H,\Delta \bar S) $ (\Delta \bar G,\Delta \bar H,\Delta \bar S) of copper in alloys and the standard thermodynamic functions of formation and entropies of the ternary compounds and the end-member (Cu₉BiSe₆) of solid solutions based on the low-temperature Cu₂Se phase.     

Synthesis and study of Iron(II) perrhenate complexes with 4-propyl-1,2,4-triazole exhibiting 1A1 ? 5T2 spin transition

Coordination compounds of iron(II) perrhenate with 4-propyl-1,2,4-triazole (L), [Fe₃L₆(ReO₄)₄(H₂O)₂](ReO₄)₂(I), [Fe₃L₆(H₂O)₆](ReO₄)₆·H₂O(II), and FeL₃(ReO₄)₂(III), were synthesized. Compounds I and III were studied by static magnetic susceptibility measurements and by IR and electronic spectroscopy. These complexes exhibit a reversible ¹ A ₁ ⇄ ⁵ T ₂ spin transition and thermochromism. Compound I exhibits a spin transition without hysteresis at 185 K. The temperatures of forward and reverse transition for III are 250 and 244 K, respectively. Complex II isolated by crystallization from an acidified aqueous solution of compound I has a linear trinuclear structure of the cation (X-ray diffraction data). The structure of complex I was assumed to be similar, while compound III has a polymeric structure. Original Russian Text ? M.B. Bushuev, L.G. Lavrenova, Yu.G. Shvedenkov, A.V. Virovets, L.A. Sheludyakova, S.V. Larionov, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 1, pp. 51–56.     

Crystal and electronic structure of the red semiconductor Ba4LaSbGe3Se13 comprising the complex anion [Ge2Se7-Sb2Se4-Ge2Se7]

Ba₄LaGe₃SbSe₁₃ was prepared by reacting the elements under exclusion of air at 700°C, followed by slow cooling to room temperature. It crystallizes in a new type of the monoclinic space group P2₁/c, with lattice dimensions of a=1633.30(9) pm, b=1251.15(7) pm, c=1303.21(7) pm, β=103.457(2)°, V=2590.0(2) 10⁶ pm³ (Z=4). The structure contains isolated GeSe₄ as well as Ge₂Se₇ digermanate units. Two of the latter are interconnected via an Sb₂Se₄ bridge yielding an almost linear complex anion [Ge₂Se₇-Sb₂Se₄-Ge₂Se₇]¹⁴⁻. The oxidation states are assigned to be Ba^II, La^III, Ge^IV, Sb^III, and Se^−II, in accord with an electronically saturated nonmetal. The lone pair of Sb^III reflects itself in highly irregular Se coordination. The red color of the material is indicative of semiconducting behavior with an activation energy of 2.0 eV. Electronic structure calculations based on the LMTO approximation point to a smaller gap, typical for this calculation method. We utilized the COHP tool to explore the bonding character of the different Sb-Se interactions.     

Test Films for the Determination of Aromatic Amines and Hydrazines in Aqueous Solutions

Conditions of the test determination of toxic aniline (I), N,N-dimethylaniline (II), N,N-diethylaniline (III), 2,2,4-trimethyl-1,2-dihydroquinoline (IV), 1,1-dimethylhydrazine (V), and phenylhydrazine (VI) as their 4,6-dinitrobenzofuroxan (I) and 5,7-dinitrobenzofurazan (II, III, IV, V, VI) derivatives in aqueous solutions were found. Visual and spectrophotometric measurement of the signal was used. The reagents were immobilized in nitrocellulose films. Optimal results of visual determination of color development in test films were obtained with reagents immobilized in nitrocellulose at their concentration of 5 mass % and pH of the test solution in the range 6.0–7.5. The spectrophotometric measurement of the signal of test films was performed at wavelengths of 500–560 nm for I, V, and VI and 610–620 nm for II, III, and IV. The detection limit for spectrophotometric measurement was 0.01, 0.18, 0.13, 0.15, 0.16, and 0.04 mg/L for I, II, III, IV, V, and VI, respectively. The analytical range of the toxicants was 0.05–6.0 mg/L. Test determination is possible in the presence of alkylamines, ammonia, phenols, carboxylic acids, and inorganic salts.     

Thermodynamic study of glasses in Ag-As-Se system using EMF method with Ag<Subscript>4</Subscript>RbI<Subscript>5</Subscript> solid electrolyte

The EMF method with Ag₄RbI₅ solid electrolyte was used to study silver solubility in Ag-As-Se glasses on the basis of the cross-sections of (I) Ag-As_0.25Se_0.75, (II) Ag-As_0.33Se_0.67, (III) Ag-As_0.4Se_0.6, and (IV) Ag-As_0.5Se_0.5. It is found that silver solubility reaches 30 and 40 at % in sections (I), (IV) and (II), (III), accordingly. The data of EMF measurements were used as a basis for calculation of partial polar functions of Ag in glasses. The Gibbs-Duhem equations were integrated to calculate thermodynamic functions of silver dissolution in vitreous As _x Se_{1 − x} (x = 0.25; 0.33; 0.4; 0.5), from which the corresponding data for the latter were used to obtain the standard integral thermodynamic functions of the mixing of glasses. The obtained results were compared with the thermodynamic data for crystalline silver selenoarsenites.     

Phase equilibria in the Tl2Te-SnTe-Bi2Te3 system

phase equilibria in the Tl₂Te-SnTe-Bi₂Te₃ system were studied by differential thermal analysis (DTA), X-ray powder diffraction, and microhardness measurements. Some polythermal sections and isothermal (at 600 and 800 K) sections of the phase diagram and a projection of the liquidus surface were constructed. It was shown that the system is characterized by the formation of solid solutions with the Tl₅Te₃ structure (δ) and solid solutions based on SnTe (γ₁), Tl₂Te (α), Bi₂Te₃ (β), and two TlBiTe₂ (γ₂ and γ′₂) phases. Their homogeneity regions were determined. The liquidus surface consists of the primary crystallization fields of the β-, γ₁-, γ′₂-, and δ phases and the compounds SnBi₂Te₄ and SnBi₄Te₇. The liquidus of the α phase is degenerate. The primary crystallization fields of phases were determined, and the types and coordinates of in- and monovariant equilibria were found.     

Study of substituent effects on rotational isomers and monomer–dimer equilibria of the 3-carboxy group in 4-substituted (R)-2-(3,4-methylenedioxyphenyl)-6-isopropyloxy-2H-chromen-3-carboxylic acids in dilute CCl4 and CHCl3 solutions by FTIR spectroscopy

FTIR spectra of the title carboxylic acids (I–III) with 4-substituents (H, CH₃ or C₆H₅) and their related compounds IV–VI with 4-(substituted phenyl) groups were measured in dilute CCl₄ and CHCl₃ solutions. The concentration dependence of FTIR spectra of I–IV was also measured in these solutions. These spectra were subjected to curve analysis in order to quantitatively identify the rotational isomers of 3-carboxy group attributable to steric hindrance of the 4-substituents. For I, II and III–VI, two, four and five ν(CO) bands were observed for their carboxy groups, respectively, indicative of monomer–dimer equilibrium and two and three kinds of rotational isomers for II and III–VI, respectively. Compounds III–VI were found to form intra-molecular hydrogen bonds between the trans-type of the 3-carboxy group and the π-electrons in the 4-benzene ring. We have worked out a method to estimate the association constant (K) of complicated monomer–dimer equilibria such as II–VI. The K values of I–IV decrease remarkably in the order of H (I), C₆H₅ (III), CH₃ (II) and C₆H₄-p-OCH₃ (IV) in CCl₄ and I, II, III and IV in CHCl₃; these orders are discussed.     

Phenyltellurium halide complexes of iron cyclopentadienyl dicarbonyl: Synthesis and molecular structures of CpFe(CO)2TePh, CpFe(CO)2TeBr2Ph, CpFe(CO)2TeBrPh(μ-Br)Br3TePh, and PhTeI3(C4H8O)

The bromination of CpFe(CO)₂TePh (I) affords the monomeric complex CpFe(CO)₂TePhBr₂ (II) as the major product and crystals (III), being a cocrystallizate of complexes II and CpFe(CO)₂TeBrPh(μ-Br)TePhBr₃ (IIIA). Complex IIIA contains a PhTeBr₃ molecule, which is weakly bound because of the lone electron pair (LEP) of the bridging bromine atom of molecule II. An analogous weak interaction with the LEP of oxygen in tetrahydrofuran (Te…O 2.893 ?) is observed in the PhTeI₃(THF) adduct (IV), which is a dimer with two bridging iodine atoms and can be obtained by the crystallization of PhTeI₃ from THF. According to the X-ray diffraction data, the Fe-Te distances in compounds II and IIIA (on the average, 2.5 ?) differ slightly and are similarly shortened by 0.2 ? compared to the sum of the covalent radii of iron and tellurium. The secondary interactions Te…halide and Te…π system of the phenyl ligand are discussed. Original Russian Text ? Yu.V. Torubaev, A.A. Pasynskii, I.V. Skabitskii, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 5, pp. 347–352.     

Synthesis and structure of [Ph3MeP]3[Sb3I12]·Me2C=O, [Ph3MeP]3[Sb2I9], [Ph3MeP]2[SbI5], and [Ph3MeP]3[Sb3I12] antimony complexes

Complexes [Ph₃MeP]₃[Sb₃I₁₂]Me₂C=O (I), [Ph₃MeP]₃[Sb₂I₉] (II), and [Ph₃MeP]₂[SbI₅] (III) were obtained via the reaction of triphenylphosphonium iodide with antimony triiodide in acetone in 1:1, 3:2 and 2:1 molar ratios. Reaction of the complex III with antimony triiodide (1:1) affords [Ph₃MeP]₃[Sb₃I₁₂] (IV). The structure of the obtained complexes was confirmed by X-ray analysis.     

Reciprocal system 3Tl2S + Bi2Se3 ↔ 3Tl2Se + Bi2S3

The reciprocal system 3Tl₂S + Bi₂Se₃ ? 3Tl₂Se + Bi₂S₃ has been investigated by DTA, X-ray powder diffraction analysis, and emf measurements. Some polythermal sections and the isothermal section at 500 K of the phase diagram and the projection of the liquidus surface of this system have been constructed, and the types and coordinates of the invariant and univariant equilibria have been determined. The existence of wide regions of quaternary solid solutions based on the binary compounds Tl₂S, Tl₂Se, Bi₂S₃, and Bi₂Se₃, and solid solutions between the temary compounds TlBiS₂ and TlBiSe₂ have been established.     

Synthesis and molecular structures of the cobalt complexes (η4-C4Me4)Co(CO)2SnCl3, (η4-C4Me4)Co(CO)2(TeI2Ph), and (η4-C4Me4)Co(CO)2 (TeBrIPh) with the shortened Co-Sn and Co-Te bonds

The complex (η⁴-C₄Me₄)Co(CO)₂I (I) reacted with excess SnCl₂ in boiling THF to give, through replacement of the iodide ligand by the fragment SnCl₃, the mononuclear complex (η⁴-C₄Me₄)Co(CO)₂SnCl₃ (II) containing the Co-Sn bond (2.459(1) ?). In a reaction of complex I with phenyltellurenyl halides PhTeI and PhTeBr, an analogous insertion into the cobalt-iodine bond yielded (η⁻C₄Me₄)Co(CO)₂(TeI₂Ph) (III) and (η⁴-C₄Me₄)Co(CO)₂(TeBrIPh) (IV), respectively. This type of coordination of the aryltellurenyl halide fragment to the transition metal atom was observed for the first time. X-ray diffraction analysis revealed a substantial shortening of the formally single Co-Sn and Co-Te bonds in complexes II–IV compared to the sum of the covalent radii of the corresponding atoms. Original Russian Text ? Yu.V. Torubaev, A.A. Pasynskii, A.R. Galustyan, p. Mathur, 2009, published in Koordinatsionnaya Khimiya, 2009, vol. 35, No. 1, pp. 3–7.     

Comparison of Carboxamides Reactivity with Respect to Benzoyl Chloride and Diphenyl Chlorophosphate in Acetonitrile

For amides belonging to series RCONH₂ (I), RCONHMe (II), RCONHPh (III), and RCONMe₂ (IV) rate constants k₁ (l mol^-1 s^-1) were determined (in acetonitrile at 25°C) specifying the nucleophilic reactivity of the oxygen atom in amides toward benzoyl chloride and diphenyl chlorophosphate. The lack of substrate selectivity in the reactions in question was established. For equal values of inductive constants ^* of the R substituents the reactivity sequence of amides with respect to both substrates is the same (I >> IV > II, and III > II), and it does not follow the corresponding sequence of basicities. A conclusion was drawn that both groups of reactions proceed through cyclic transition states resembling reagents: six-membered with amides I and III, and five-membered with amides II and IV.