Tetravalent Tellurium Ligands

Oxidative addition of TeCl₄ to Vaska's complex gave the trichlorotelluronium complex [IrCl₂(TeCl₃)(CO)(PPh₃)₂] (structure depicted), which contains a rare example of a structurally characterized tetravalent tellurium ligand. The coordination at the Te^IV center is—in full agreement with the VSEPR model—distorted trigonal bipyramidal.     

Synthesis of CdTe Quantum Dots with Tunable Photoluminescence Using Tellurium Dioxide as Tellurium Source

A simple and convenient method has been developed for synthesis of water‐soluble CdTe quantum dots (QDs) under ambient atmospheric conditions. In contrast to the traditional aqueous synthesis, green to red emitting CdTe QDs were prepared by using TeO₂ to replace Te or Al₂Te₃ as tellurium source in this method. The influences of experimental variables, including pH value, 3‐mercaptopropionic acid (MPA)/Cd and Te/Cd molar ratios, on the emission peak and photoluminescence (PL) quantum yield (QY) of the obtained CdTe QDs have been systematically investigated. Experimental results indicate that green to red emitting CdTe QDs with a maximum photoluminescence quantum yield of 35.4% can be prepared at pH 11.3 and n_(Cd):n_(Te):n_(MPA)=1:0.1:1.7.     

由工业碲制备高纯碲

碲是制作半导体，制冷元件，光电元件等的理想材料．随着航天、航空、军事、电子以及制冷、玻璃、有机合成工业等的迅速发展，对碲及其化合物的需求量和纯度要求越来越高［１］．文献［２］所述制备高纯碲的方法为溶５０ｇ工业碲（９９．９％）于王水中，过滤．然后在滤液...     

Antibacterial Activities of Tellurium Nanomaterials

We prepared four differently shaped Te nanomaterials (NMs) as antibacterial reagents against Escherichia coli. By controlling the concentrations of hydrazine (N₂H₄) as reducing agent, NaCl, and temperature, we prepared Te nanowires, nanopencils, nanorices, and nanocubes. These four Te NMs resulted in a live/dead ratio of E. coli cells of less than 0.1, which is smaller than that of Ag nanoparticles. The order of antibacterial activity against E. coli is nanocubes ≈ nanorices > nanopencils ≈ nanowires. This is in good agreement with the concentration order of tellurite (TeO₃²⁻) ions released from Te NMs in E. coli cells, revealing that TeO₃²⁻ ions account for the antibacterial activity of the four Te NMs. We found that spherical Te nanoparticles (32 nm in diameter) with TeO₃²⁻ ions were formed in the E. coli cells. Compared to Ag nanoparticles that are commonly used as antibacterial reagents, Te NMs have higher antibacterial activity and lower toxicity. Thus, Te NMs hold great practical potential as a new and efficient antibacterial agent.     

Determination of Tellurium by Electrothermal Atomic Absorption Spectroscopy: Isolation of Tellurium from Potential Interferences

Abstract

The determination of tellurium at nanogram levels using electrothermal atomic absorption spectroscopy is examined. Severe interferences are observed in the presence of many elements but can be overcome by the use of a sequential extraction scheme.     

火焰原子吸收光谱法测定硒碲混合物中的碲

建立了酒石酸-硝酸-盐酸混酸溶解样品,在王水-酒石酸介质中,采用空气-乙炔火焰在原子吸收光谱仪上测定硒碲混合物中碲的方法。研究了样品处理方法、乙炔流量、燃烧高度、灯电流、溶液介质等有关工作条件。实验表明碲浓度在1～20μg/mL范围内与吸光度呈良好的线性关系,回归方程为A=0.0229C+0.0009,相关系数0.9998,检出限0.08μg/mL。适合于硒碲混合物中碲的测定,相对标准偏差为0.9%～1.3%,回收率为98%～102%。     

Alkoxytelluration of Styrene with Tellurium Tetrahalides

Russian Journal of General Chemistry - An efficient synthesis of the earlier unknown trichloro- and tribromo(2-ahkoxy-2-phenylethyl)-λ4-tellanes with yields of 90 to 100% has been developed...     

Tellurium Chloride Complexes in Nonaqueous Solutions

Tellurium(IV) complexes (R₄N)₂[TeCl₆] (T6), (R₄N)[TeCl₅] (T5), and (R₄N)[TeCl₄OH] (T4), where (R₄N)⁺ is tetrabutyl, tetraoctyl, and trialkyl benzyl ammonium cations, were synthesized. Tellurium distribution between aqueous HCl solutions and trialkyl benzyl ammonium chloride solution in caprylic acid was studied. The ¹²⁵Te NMR spectra of aqueous HCl solutions of tellurium have a single averaged peak, whose chemical shift (CS) depends on the acid concentration. ¹²⁵Te NMR spectroscopy has shown that the T4 complex in nonaqueous solutions is kinetically inert and the ligand exchange with the T6 and T5 complexes is retarded. In contrast, the T5 and T6 complexes, when simultaneously present in nonaqueous solutions, rapidly exchange ligands. ¹²⁵Te NMR, IR, Raman, and UV spectroscopic studies have shown that under standard conditions, the reaction (Bu₄N)[TeCl₅]+Bu₄NCl = (Bu₄N)₂[TeCl₆] G⁰ = -19.1(1 ± 0.3) kJ/mol and H⁰ = -6.5(1 ± 0.2) kJ/mol) takes place in methylene chloride solution. The symmetry groups of the synthesized complexes in the solid state and CSs for tellurium solutions (0.2 gatom/liter Te) in methylene chloride were determined: O_h and –58 ppm for T6; C_4v and +75 ppm for T5; and C_3v and +54 ppm for T4 (CS = 0 for a 0.2 mol/liter TeO₂ solution in 11.4 mol/liter HCl).     

The atomic absorption spectroscopy of Tellurium

Telluiium can be determined by atomic absorption spetroscopy at 2143, 2359, and 2386 A The sensitivities for these lines are in the ratio of 1.9.9 187 With aqueous solutions, a Beckman triple-buiner (air-hydrogen) and a 5-pass optical system, the line 2143 Å has a sensitivity of 0.23 p.p.m , and a detection limit ot 0.076 p.p.m The sensitivities for this line in acqueous and organic solvents, and in air-hydrogen and air-acetylene flames were studied and the optimum conditions determined Where necessary, preconcentration of tellurium by coprecipitation with elemental arsenic, 01 by extraction of K₂Tel₆ or tellurium diethyldithiocarbomate with MIBK can be applied, the latter gives a two-fold enhancement in sensitivity compared with aqueous solutions.     

Voltammetric Ultra Trace Determination of Tellurium

Abstract

A simple and convenient method is described for the determination of low concentration tellurium based on differential pulse polarographic reduction of Te(IV) in alkaline medium. Linearity of the calibration curve was achieved up to 25.5 ppm with a limit of determination of 0.02 µg/mL. The possible interference of coexisting metal ions was examined and ruled out. The method has been successfully applied for the analysis of tellurium in industrial waste samples.     

催化动力学光度法测定痕量碲的研究

本文研究了甲基红，次磷酸钠，钯（Ⅱ），碲（Ⅳ）之间的催化反应，建立了一种测定超痕量碲（Ⅳ）的新方法，方法检出限为１．２×１０＾－１１ｇ／ｍＬＴｅ（Ⅳ）测定范围为０．００１～０．１μｇ／２５ｍＬＴｅ（Ⅳ），用于测定生物样品中的痕量Ｔｅ（Ⅳ）获得了满意结果。     

Thermodynamic properties of Iron—Tellurium alloys

Vapor pressures of tellurium of iron—tellurium alloys were determined between 550 and 900°C and between 0 and 67 at % Te by an isopiestic method. Activities and partial molar enthalpies of tellurium were calculated and integral free energies of formation were obtained by aGibbs-Duhem integration. Two statistical models were used to calculate activities in the hexagonal δ′-NiAs phase. Excellent agreement with the experimental values was obtained by assuming random distribution of iron atoms and iron vacancies in the defected (00 1/2) layers of the lattice. The interaction energy between iron vacancies was found to be 820 cal·g-atom^?1.

     

Thermodynamic properties of chromium—Tellurium alloys

Tellurium vapor pressures of chromium—tellurium alloys were determined in the range of NiAs-type structures between 800 and 1,300 K and between 55 and 62 at% Te by an isopiestic method. The partial molar quantities of tellurium were derived, and the results critically compared with data reported in the literature.

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Thermodynamische Eigenschaften von Chrom—Tellur-Legierungen

Zusammenfassung Die Tellurdampfdrücke von Chrom—Tellur-Legierungen wurden mit Hilfe einer isopiestischen Methode im Bereich der Phasen mit NiAs-ähnlichen Strukturen zwischen 800 und 1300 K und zwischen 55 und 62 At% Te bestimmt. Die partiellen molaren Eigenschaften von Tellur wurden daraus abgeleitet, und die Resultate kritisch mit Literaturwerten verglichen.

     

微波等离子体光谱法测定碲的研究

微波等离子体原子发射光谱法(MIPAES)测定碲,前人已作过一些工作。本文利用我们建立的微量进样系统与MIPAES联用,对碲的测定进行了研究。实验中发现,加入适量的SnCl_2可降低检出限约一个数量级,Te_(214.3nm)的检出限为5 ng/mL,同时还研究了碱金属卤化物对碲的测定的影响。     

Peroxide Coordination of Tellurium in Aqueous Solutions

Tellurium–peroxo complexes in aqueous solutions have never been reported. In this work, ammonium peroxotellurates (NH₄)₄Te₂(μ‐OO)₂(μ‐O)O₄(OH)₂ ( 1 ) and (NH₄)₅Te₂(μ‐OO)₂(μ‐O)O₅(OH)?1.28 H₂O?0.72 H₂O₂ ( 2 ) were isolated from 5 % hydrogen peroxide aqueous solutions of ammonium tellurate and characterized by single‐crystal and powder X‐ray diffraction analysis, by Raman spectroscopy and thermal analysis. The crystal structure of 1 comprises ammonium cations and a symmetric binuclear peroxotellurate anion [Te₂(μ‐OO)₂(μ‐O)O₄(OH)₂]^4?. The structure of 2 consists of an unsymmetrical [Te₂(μ‐OO)₂(μ‐O)O₅(OH)]^5? anion, ammonium cations, hydrogen peroxide, and water. Peroxotellurate anions in both 1 and 2 contain a binuclear Te₂(μ‐OO)₂(μ‐O) fragment with one μ‐oxo‐ and two μ‐peroxo bridging groups. ¹²⁵Te NMR spectroscopic analysis shows that the peroxo bridged bitellurate anions are the dominant species in solution, with 3–40 %wt H₂O₂ and for pH values above 9. DFT calculations of the peroxotellurate anion confirm its higher thermodynamic stability compared with those of the oxotellurate analogues. This is the first direct evidence for tellurium–peroxide coordination in any aqueous system and the first report of inorganic tellurium–peroxo complexes. General features common to all reported p‐block element peroxides could be discerned by the characterization of aqueous and crystalline peroxotellurates.