Tellurium tetrachloride: an improved method of preparation

An efficient and practical synthesis of tellurium tetrachloride from elemental tellurium and sulfuryl chloride is described.     

[Te6N8(TeCl4)4]—Tellurium Nitride Stabilized by Tellurium Tetrachloride

Shielding by four TeCl ₄ molecules is observed for the distorted rhombic dodecahedron core of the tellurium nitride Te₆N₈ (see picture). With the characterization of this structure, the composition of the tellurium nitride discovered 100 years ago has now been determined. As a result of the shielding effect, the explosive character of the nitride is lost.     

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.     

Recent Advance of Tellurium for Biomedical Applications

Tellurium(Te) nanomaterials have aroused a wide interest in semiconductor, thermoelectric, piezoelectric, as well as biomedical applications. The last decades of reports indicated a major nanostructure of one-dimensional (1D) Te on account of its inherent structural anisotropy. Two-dimenional(2D) Te has been newly developed and drawn a lot of interests recently. This review presents the intrinsic biological potential of Te-based nanomaterials and summarizes their up-to-date advance in phototherapy and reactive oxygen species(ROS)-related applications in the biomedical field.     

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.     

Generation of Ir-Sn and Rh-Sn bonds from the oxidative addition of tin(IV) halides to [Ir(μ-Cl)(1,5-COD)]2 and [Rh(μ-Cl)(1,5-COD)]2

Facile oxidative addition of SnCl₄, MeSnCl₃, and SnBr₄ across Ir(I) and Rh(I) cyclooctadiene complexes resulted in the formation of the corresponding Ir-Sn and Rh-Sn heterobimetallic complexes. Treatment of SnCl₄ with [Ir(COD)(μ-Cl)]₂ and [Rh(COD)(μ-Cl)]₂ afforded [Ir(COD)(μ-Cl)Cl(SnCl₃)]₂ (1) and [Rh(COD)(μ-Cl)Cl(SnCl₃)]₂ (2), respectively. Reaction of the organotin halide MeSnCl₃ with [Ir(COD)(μ-Cl)]₂ led to the formation of [Ir(COD)(μ-Cl)Cl(MeSnCl₂)]₂ (3). The reaction of SnBr₄ to Ir^I and Rh^I precursors gave [Ir(COD)(μ-Br)Br(SnBr₃)]₂ (4) and [Rh(COD)(μ-Br)Br(SnBr₃)]₂ (5) respectively, which indicates halide exchange at post-oxidative addition stage. The structures of complexes 1-5 were confirmed by X-ray crystallography. A cis-addition of Sn-X bond across Ir^I/Rh^I is proposed from the analysis of the geometrical features of “X-M-Sn” triangular units in 1-5.     

The vinylation of aryl iodides catalysed by Co, Rh and Ir complexes

The CoCl(PPh₃)₃, RhCl(PPh₃)₃, and IrClCO(PPh₃)₂ catalysed vinylation of aryl iodides proceeds to give cinnamates and stilbene in high yields.     

Facile Oxidative Addition of O−H Bonds of Methanol and Water to IrI Complexes Having Peraryldiphosphane Ligands

A new piece in the puzzle. Hydrido(alkoxo) complexes of late transition metals have often been postulated as intermediates or transition states in the catalytic hydrogenation of carbonyl compounds and catalytic hydrogen transfer reactions. Here the facile oxidative addition of the O−H bonds of alcohol and water to iridium(I ) complexes of peraryldiphosphanes [Eq. (a)] is reported and the resulting complexes are described. R=H, Me.     

碲在汞中的扩散系数和溶解度

用阴极溶出计时安培法测定了碲在汞中的扩散系数和溶解度.在1 mol/L NH_3-NH_4 Cl和10~(-3)mol/L TeO_3~(2-)溶液中,用悬汞电极于-0.90 V进行预电解,使Te(Ⅳ)还原到元素Te.然后在另一个电解池中阴极溶出使Te还原为Te~(2-).阴极溶出是在0.1 mol/L NaOH溶液中,用计时安培法于-1.40 V测定.根据下列方程式计算了碲在汞中的扩散系数D及溶解度S:D=r_0~2/πt_0,S=(4nFπ~(3/2)D~(3/2)t_0)~(-1)(Δi_1/Δt~(-1/2).D和S的测定值分别为:1.52×10~(-5)cm~2/s及2.34×10~(-3)wt％.实验结果表明碲在汞中以单原子态存在.     

Determination of Tellurium by Gas Phase Molecular Absorption Spectrometry After Hydrogen Telluride Generation

Abstract

A method for determination of tellurium(IV) or tellurium(VI) is described that involves hydrogen telluride generation by reduction with sodium tetrahydro-borate(III), evolution of hydride with HCl solution, transport into a flow-cell placed in a UV-visible molecular absorption spectrophotometer and measurement of gas at 190 nm. Hydride generation and determination procedures are optimized, based on height and area of absorbance versus time profile of hydrogen telluride generated. Using the best experimental conditions found the calibration curve is linear from 5 to 100 μg/ml of tellurium, 1.1 μg/ml of tellurium(IV) or 3.1 μg/ml of tellurium(VI) can be detected, and relative standard deviation ranges from 4 to 7%. The method is applied to the analysis of additives for synthetic rubber making.     

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。     

New Forms and Functions of Tellurium: From Polycations to Metal Halide Tellurides

Metal chalcogenides and metal chalcogenide halides are distinguished by their structural diversity and by their very different physical properties. Therefore, the synthesis of novel compounds from this class is always a rewarding goal for the preparatively oriented solid-state chemist. Over the past few years, many syntheses and structural investigations have stimulated the field. The emphasis of the research has been placed on selenium-rich and tellurium-rich compounds, which are characterized by directed covalent bonds between the chalcogen atoms. Compounds with novel chalcogen polycations have also become accessible during the past few years by reacting the chalcogen elements with transition metal halides, or from chemical vapor deposition in the sense of chemical transport reactions. In these compounds, tellurium differs from its lighter homologues by a pronounced tendency towards greater covalence. This article attmepts to provide an overview of new developments in the field of compounds with chalcogen polycations and of metal chalcogenide halides, with an emphasis on compounds containing molybdenum and tungsten as the transition metals and tellurium as the chalcogen.     

The reactions of Ir(CO)Cl(PPh3)2 with HSnPh3

A reinvestigation of the reaction of Ir(CO)Cl(PPh₃)₂, 1 with HSnPh₃ has revealed that the oxidative-addition product Ir(CO)Cl(PPh₃)₂(H)(SnPh₃), 2 has the H and SnPh₃ ligands in cis-related coordination sites. Compound 2 reacts with a second equivalent of HSnPh₃ by a Cl for H ligand exchange to yield the new compound H₂Ir(CO)(SnPh₃)(PPh₃)₂, 3. Compound 3 contains two cis- related hydride ligands. Under an atmosphere of CO, 1 reacts with HSnPh₃ to replace the Cl ligand with SnPh₃ and one of the PPh₃ ligands with a CO ligand and also adds a second equivalent of CO to yield the 5-coordinate complex Ir(CO)₃(SnPh₃)(PPh₃), 4. Compound 4 reacts with HSnPh₃ by loss of CO and oxidative addition of the Sn-H bond to yield the 6-coordinate complex HIr(CO)₂(SnPh₃)₂(PPh₃), 5 that contains two trans-positioned SnPh₃ ligands.     

Syntheses and Structures of Four New Tellurium(II) Complexes

The four Te^II complexes, cis‐[TeCl₂{(ⁱPrNH)₂CS}₂] ( 1 ), cis‐[TeCl₂{(ⁱBuNH)₂CS}₂] ( 2 ), trans‐[TeCl₂{(PhNMe)₂CS}₂] ( 3 ), and trans‐[TeCl₂{(Et₂N)₂CS}₂] ( 4 ), have been synthesised and their molecular structures solved by means of X‐ray crystallography. All four complexes are square planar, those with disubstituted thiourea ligands have a cis configuration, those with tetrasubstituted thioureas have a trans configuration. The Te–S bond lengths in 1 and 2 average 2.4994 and 2.5213 Å, respectively. The Te–Cl bonds trans to the Te–S bonds have average lengths of 2.8754 and 2.8334 Å, reflecting the trans influence of the two disubstituted thioureas. In 3 and 4 with identical ligands trans to each other, the average Te–S and Te–Cl bond lengths are 2.6834 and 2.5964 Å, respectively.     

New CF3 Substituted Phosphorus‐Tellurium Heterocycles

The reaction of trifluormethyl dichlorophosphine (CF₃PCl₂) with sodium telluride Na₂Te or bis(trimethylsilyl) telluride (Me₃Si)₂Te results in the formation of four new phosphorus tellurium heterocycles ( 1–4 ) with the electron withdrawing CF₃ substituent bonded to phosphorus. The telluratriphosphetane (CF₃P)₃Te ( 1 ), telluratetraphospholane (CF₃P)₄Te ( 2 ), telluradiphosphirane (CF₃P)₂Te ( 3 ) and ditelluratriphospholane (CF₃P)₃Te₂ ( 4 ) are characterized by multinuclear (³¹P, ¹⁹F and ¹²⁵Te) NMR spectroscopy. A full analysis of the ¹⁹F NMR spectrum of telluratriphosphetane (CF₃P)₃Te is presented. The new heterocycles are remarkably stable in solution and eliminate only slowly tellurium to form cyclophosphines (CF₃P)_n (n = 3–5).     

A kinetic investigation of the oxidative addition reactions of the dimeric Bu4N[Ir2(μ-Dcbp)(CO)2(PCy3)2] complex with iodomethane

The IR and UV/visible kinetic results of the oxidative addition of iodomethane to Bu₄N[Ir₂(μ-Dcbp)(CO)₂(PCy₃)₂] (Dcbp = 3,5-dicarboxylatepyrazolate anion) showed three time separable reactions. The first, very fast reaction corresponds to the a Ir(I)-Ir(III) alkyl species formation within 10⁻³ s. The second, relative fast reaction corresponds to Ir(III)-Ir(III) alkyl formation with a rate constant of 3.25(4) × 10⁻² M⁻¹ s⁻¹ while the third and slowest reaction corresponds to Ir(III)-Ir(III) acyl formation with a rate constant of 1.42 × 10⁻⁵ s⁻¹. The IR data clearly show the existence of a number of equilibria with the formation of an Ir(I)-Ir(III) alkyl product which then react to form the Ir(III)-Ir(III) which then slowly react to form the Ir(III)-Ir(III) acyl product. A solvent study indicated increased oxidative addition activity in the presence of polar solvents, which is indicative of a polar transition state. The large negative entropy of activation for the Ir(III)-Ir(III) alkyl formation step (k₂) of −178(23) JK⁻¹ mol⁻¹ is indicative of an associative process. DFT calculations successfully identified the stereochemistry of the starting complex, [Ir₂(μ-Dcbp)(CO)₂(PCy₃)₂]⁻ as well as that of the Ir-alkyl and acyl isomers. A reaction pathway, using the IR data and DFT calculations, is proposed for the reaction.     

Tellurium/lithium exchange reactions in the synthesis of spiroketals and 1,6-dioxygenated systems

1,4-C,O-dianions have been generated through concomitant acid/base and tellurium/lithium exchange reactions. The di-lithium salts were transmetallated with cerium chloride to the corresponding di-cerium salts and subsequently reacted with lactones and carboxylic acid anhydrides to yield the respective spiroketals. The di-lithium entities were also converted into the corresponding cyanocuprates that add in a 1,4-manner to 2-cyclohexen-1-one to form 1,6-dioxygenated compounds.     

人发和血清中痕量碲的示波极谱测定

碲（ＩＶ）在０．０３ｍｏｌ／Ｌ草酸－０．０００６％次甲基蓝介质中，在电位－０．６５Ｖ（ｖｓ．ＳＣＥ）处，有一尖锐灵敏的导数极谐波，峰电流与浓度在１．０×１０－４～１．５×１０－２μｇ／ｍＬ之间里线性关系，检测限为４．０×１０－５μｇ／ｍＬ．该法应用于人发及血清中痕量碲的测定，结果准确可靠．     

Tellurium azamacrocycles: synthesis, characterization and coordination studies

The metal-free condensation of bis(2-formylphenyl) telluride (1) with a series of diamines affords macrocyclic tellurium ligands 2-7. Crystals of the protonated macrocycle 8 are monoclinic, space group P2/n with a=10.890(5), b=7.414(4), c=24.334(13) Å, Z=2. The reaction of tellurium containing macrocyclic Schiff base 2 with Pd(C₆H₅CN)₂Cl₂ gives the expected 1:1 product [Pd(II) 2] Cl₂ (9). Complex 9 was treated with excess of NH₄PF₆ in methanol to give the analogous PF₆⁻ salt [Pd(II) 2] (PF₆)₂ (10). The crystals of 10 are monoclinic, space group P2₁/n, a=8.2250(10), b=21.280 (4), c=21.150 (4), Z=4. However, the reaction of 2 with Pt(COD)Cl₂ proceeds via novel transmetallation to yield an organoplatinum complex (11). The crystals of 11 are also monoclinic, space group P2₁/n, a=12.3253 (14), b=14.6557 (14), C=13.4054 (11), Z=4. The octahedral Ni(II) complex 12 was prepared by the reaction of NiCl₂ · 6H₂O with 2 and NH₄PF₆ under an inert atmosphere. For 12: triclinic, space group ; Z=2; a=10.800(8), b=13.468(9), c=13.918(11), α=89.67(6)°, β=101.53(7)°, γ=81.49(3)° and V=1961(3). Cyclic voltammetry of 12 in MeCN solution shows a well-behaved quasi-reversible (ΔE=100 mV) Ni(III) ↔ Ni(II) couple.