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).     

Coexistence of Tellurium Cations and Anions in Phosphonium-Based Ionic Liquids

Elemental tellurium readily dissolves in ionic liquids (ILs) based on tetraalkylphosphonium cations even at temperatures below 100 °C. In the case of ILs with acetate, decanoate, or dicyanamide anions, dark red to purple colored solutions form. A study combining NMR, UV-Vis and Raman spectroscopy revealed the formation of tellurium anions (Te_n)²⁻ with chain lengths up to at least n=5, which are in dynamic equilibrium with each other. Since external influences could be excluded and no evidence of an ionic liquid reaction was found, disproportionation of the tellurium is the only possible dissolution mechanism. Although the spectroscopic detection of tellurium cations in these solutions is difficult, the coexistence of tellurium cations, such as (Te₄)²⁺ and (Te₆)⁴⁺, and tellurium anions could be proven by cyclic voltammetry and electrodeposition experiments. DFT calculations indicate that electrostatic interactions with the ions of the ILs are sufficient to stabilize both types of tellurium ions in solution.     

Synthesis and polycondensation of some new organic tellurium compounds containing mono- and di-amino groups

Several new and known organic tellurium compounds containing amino groups (i.e. ArTeBr₃, Ar₂Te₂ and Ar₂Te, where Ar= 4-NH₂C₆H₄, 2-NH₂C₆H₄, 4-CH₃CONHC₆H₄ or 2-NH₂-5-NO₂-C₆H₃) were prepared by reacting aminoarylmercury chlorides with tellurium tetrabromide in glacial acetic acid. Bis(4-aminophenyl) telluride and bis(2-amino-5-nitrophenyl) telluride were polymerized with aromatic and aliphatic diacid chlorides (i.e. terephthaloyl chloride and sebacoyl chloride), as well as with toluene di-isocyanate, leading to new organic tellurium polyamides and polyurea. All organic tellurium compounds and their condensation polymers were characterized by elemental analyses, IR, ¹H and ¹³C NMR, and mass spectroscopy. The thermal stabilities of the resulting polymers were determined by thermogravimetric and derivative thermogravimetric techniques. © 1998 John Wiley & Sons, Ltd.     

Metastable P-Tellurium-Substituted Phosphaalkenes: Formation, 125Te- and 31P-NMR Spectroscopic Characterization,and Decomposition

Abstract

The formation and decomposition of P-tellurium-substituted phosphaalkenes was followed by ³¹P- and ¹²⁵Te-NMR spectroscopy. Acyclic compounds with C?P-Te moieties are in general thermally labile, but bulky substituents enhance the lifetime of a number of species. The P-chlorophosphaalkene (Me₃Si)₂C?PCl (1a) reacts with the disilyltelluride (iPrMe₂Si)₂Te (2) leading to the mixed-substituted telluride (Me₃Si)₂C?PTeSiMe₂iPr 3a which reacts with another equivalent of 1a furnishing the tellurobis(phosphaalkene) [(Me₃Si)₂C?P]₂Te (4a). 4a is a shortlived compound decomposing thermally with precipitation of elemental tellurium, leading to a known diphosphabicyclobutane 5a. In a similar way, the bulkier P-chlorophosphaalkene (iPrMe₂Si)₂C?PCl (1b) reacts with (iPrMe₃Si)₂Te furnishing [(iPrMe₂Si)₂C?P]₂Te (4b), which loses tellurium much more slowly than 4a and can be kept in cold solutions for an extended time. Reactions of in situ-prepared lithium aryltellurolates LiTeAr 6 – 9 [Ar?Ph: 6, Ar?2,4,6-Me₃Ph (?Mes): 7, Ar?2,4,6-iPr₃Ph (?TIP): 8, Ar?2,4,6-tBu₃Ph (?Mes*): 9] with 1a provide P-aryltellurophosphaalkenes 10 – 13, which decompose with the loss of diarylditellurides leading to 5a. After a 2 + 4 cycloaddition trapping experiment of 12 with cyclopentadiene, a metastable P-aryltelluro phosphanorbornene 14 was detected by ³¹P-NMR. Reactions of elemental tellurium with P-phosphanylphosphaalkenes (Me₃Si)₂C?PPR′R′;′ 15 – 17 (R′, R′′?iPr: 15; R′?iPr, R′′?tBu: 16; R′, R′′?tBu: 17) lead to metastable insertion products (Me₃Si)₂C?PTePR′R′′ 18 – 20 that decompose with formation of the tellurobisphosphanes (R′R′′P)₂Te 21 – 23, and of the bicyclic diphosphane 5a, which isomerises thermally to the diphosphabicyclooctane 24. The P-di-i-propylphosphanyl-phosphanorbornene 25 dismutates under the action of tellurium into the symmetric diphosphanes iPr₄P₂ and bis-phosphanorbornene 26. The tellurium-free products 24 and 26 were characterized by X-ray crystallography.     

Cadmium atomic layers on tellurium electrodes

The process of electrodeposition of atomic layers of cadmium Cd_ad at order of magnitude polycrystalline tellurium electrodes at potentials in excess of equilibrium potential E _Cd ²⁺/_Cd (underpotential deposition, UPD) is studied. In acid sulfate solutions (0.1 M H₂SO₄ + 0.05 M CdSO₄), the magnitude of underpotential (underpotential shift) ΔE ^UPD = 0.41 V. In cyclic voltammograms, the anodic oxidation of Cd_ad is recorded in the form of two peaks of anodic current that are displaced relative to one another in the potential scale (weakly and strongly bound adatoms). The cadmium UPD process on tellurium is accompanied by the diffusion of cadmium into the bulk of tellurium and a transition from a 2D structure Cd_ad/Te to 3D CdTe nanostructures, which are distributed in the tellurium matrix. In contrast with tellurium, the Te/CdTe_nano heterostructure exhibits photoelectrochemical activity, i.e. it generates a cathodic photocurrent.     

13C n.m.r. spectroscopy of diethyl alkyl- and benzyl-phosphonates. A study of phosphorus–carbon spin–spin coupling constants over one to seven bonds

¹³C chemical shifts and ³¹P? ¹³C spin–spin coupling constants are reported for 10 alkyl-, 20 benzyl- and 3 (naphthylmethyl)-phosphonates. While in saturated aliphatic chains P–C couplings over more than four bonds cannot be resolved, couplings over up to seven bonds are observed in the benzyl type systems. Conformational and substituent effects on J(PC) are studied and discussed. ⁿJ(PF) (n = 4, 5, 6) are reported for the isomeric (fluorobenzyl)phosphonates and ⁿJ(PP) (n = 5, 6, 7) were obtained from the ¹³C satellites in the ³¹P n.m.r. spectra of the isomeric diphosphonates, C₆H₄[CH₂P(O)(OEt)₂]₂. Comparison of those ¹³C absorptions of the latter, which represent the X parts of ABX or AA′X spin systems, with the spectra of the corresponding (methylbenzyl)phosphonates, CH₃C₆H₄CH₂P(O)(OEt)₂, yielded the relative signs of ⁿJ(PC) (n = 2–6).     

The ligational behaviour of thiosemicarbazones and semicarbazones with tellurium(IV)—reactions with TeCl4

The reactions of thiosemicarbazones and semicarbazones of benzaldehyde, salicylaldehyde, acetophenone and 2-hydroxyacetophenone with TeCl₄ give the complexes LTeCl₄, (LH)TeCl₃ or (LH)Te₂Cl₇ (L = semicarbazone or thiosemicarbazone). The structural features of these tellurium derivatives are explored by IR, ¹H and ¹³C NMR, and conductance (in acetonitrile) measurements, and structures based on an octahedral arrangement of ligands around tellurium are proposed. The presence of facial and meridian isomers in equilibrium is indicated in some cases. The complexation occurs through S/O, the nitrogen of the > CN group and O⁻ (if present on benzene ring). The (LH)Te₂Cl₇ species seem to have chlorine bridged and octahedrally coordinated tellurium.     

Characterization of isomeric [CH5P]+˙ and [C2H7P]+˙ radical cations and some [C2H6P]+ phosphonium ions in the gas phase by their collisional activation spectra

Collisional activation spectra were used to characterize isomeric ion structures for [CH₅P]^+˙ and [C₂H₇P]^+˙ radical cations and [C₂H₆P]⁺ even-electron ions. Apart from ionized methylphosphane, [CH₃PH₂]^+˙, ions of structure [CH₂PH₃]^+˙ appear to be stable in the gas phase. Among the isomeric [C₂H₇P]^+˙ ions stable ion structures [CH₂PH₂CH₃]^+˙ and [CH₂CH₂PH₃]^+˙/[CH₃CHPH₃]^+˙ are proposed as being generated by appropriate dissociative ionization reactions of alkyl phosphanes. At least three isomeric [C₂H₆]⁺ ions appear to exist, of which \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} - \mathop {\rm P}\limits^{\rm + } {\rm H = CH}_{\rm 2} $\end{document} could be identified positively.     

Tellurium(IV) Fluorides and Azides containing the Nitrogen Donor Substituent R = 2‐Me2NCH2C6H4; Crystal Structure of RTeF3 and of an Unusual Tellurium(VI) Fluoride Salt

The tellurenyl fluoride, 2‐Me₂NCH₂C₆H₄TeF, was obtained from reaction of the tellurenyl iodide RTeI with AgF. The compound was unambiguously identified by ¹⁹F and ¹²⁵Te NMR spectroscopy. The decomposition under disproportionation leads to the tellurium(IV) trifluoride, 2‐Me₂NCH₂C₆H₄TeF₃ and the ditelluride RTeTeR. The fluorination of the ditelluride, (2‐Me₂NCH₂C₆H₄Te)₂, with XeF₂ results in pure RTeF₃. The molecular structure of 2‐Me₂NCH₂C₆H₄TeF₃, the second structural characterized tellurium(IV) trifluoride, has been determined. Furthermore the syntheses of the new tellurium(IV) difluoride, (2‐Me₂NCH₂C₆H₄)₂TeF₂, and corresponding tellurium(IV) diazide, (2‐Me₂NCH₂C₆H₄)₂Te(N₃)₂ as well as the tellurium(IV) triazide, 2‐Me₂NCH₂C₆H₄Te(N₃)₃, and their characterization by spectroscopic methods were reported. During these investigations a rather interesting tellurium(VI) species was formed and the molecular structure of a subsequent product, [(2‐Me₂NHCH₂C₆H₄)₂TeF₃O]₂(SiF₆), was elucidated. Theoretical investigations for the compounds containing the stabilizing 2‐dimethylaminomethylphenyl substituent are illustrated.     

Synthesis and some reactions of a 2,2′-biphospholyl

1,1′-Diphenyl-3,3′,4,4′-tetramethyl-2,2′,5,5′-tetrahydro-2,2′-biphosphole obtained by reductive dimerization of the appropriate phosphole has been converted into the corresponding 2,2′-biphosphole by P-bromination followed by dehydrobromination of the resulting P,P′-tetrabromo compound with α-picoline. This 2,2′-biphosphole gives two isomeric P-sulfides upon reaction with sulfur, and a Mo(CO)₄ chelate upon reaction with Mo(CO)₆. Cleavage of the two P-phenyl bonds by lithium in THF yields the corresponding biphospholyl anion, which is converted into a mixture of two isomeric bis(η⁵,η⁵-2,2′-diphosphafulvalene)diirons by treatment with FeCl₂. The reaction of Mn₂(CO)₁₀ in boiling xylene affords a mixture of three complexes, including a (η⁵,η⁵-2,2′-diphosphafulvalene)hexacarbonyldimanganese produced by thermal cleavage of the two PPh bonds. Under CO pressure there is a [1,5] P → C shift of the two phenyl groups, leading to formation of (η⁵,η⁵-3,3′-diphenyl-2,2′-diphosphafulvalene)hexacarbonyldimanganese.     

(O,O′)-Diorganodithiophosphatophenyltellur(II)- und Tris[(O,O′)-diorganodithiophosphato]phenyltellur(IV)-Verbindungen; Kristallstruktur von Tris[(O,O′)-diphenyldithiophosphato]phenyltellur(IV)

(O,O′)-Diorganodithiophosphatophenyltellurium(II)- and Tris[(O,O′)-diorganodithiophosphato]phenyltellurium(IV) Compounds; Crystal Structure of Tris[(O,O′)-diphenyldithiophosphato]phenyltellur(IV) The title compounds are available by reaction of trichlorophenyltellurium(IV) respectively iodophenyltellurium(II) with the sodium or ammonium salts of (O,O′)-diorganodithiophosphorus acids in various solvents. The resulting tellurium(IV) compounds have a pronounced tendency towards reductive elimination of bis[(O,O′)-diorganothiophosphoryl]disulfanes [S₂P(OR)₂]₂ in solution. In contrast, the tellurium(II) compounds are stable, although they are disintegrated to diphenylditellane and [S₂P(OR)₂]₂ on prolonged standing in chlorinated hydrocarbons. Crystals of tris[(O,O′)-diphenyldithiophosphato]phenyltellurium(IV) are monoclinic (space group P2₁/c) with the cell constants: a = 1 039.2(1), b = 1 037.9(3), c = 4 205.0(1) pm, β = 95.273(1)°, V = 4 516.42(9)X10⁶ pm³, Z = 4. The compound appears to be monomeric in the solid state forming a distorted pentagonal bipyramid. The stereochemical influence of the lone pair of electrons causes the axial (i. e. C1? Te? S4) angle to be 156.6(1)° rather than the theoretical 180°.     

The Unique Ambiphilicity of Tellurium in the [MesitylTe(I)(I2)(I3)]− Anion

A first example of an aryltellurium(II) compound with three different bonding modes to iodine featuring covalent and non-covalent bonds such as two orthogonal, ambiphilic σ-hole interactions is introduced: [MesTe(I)(I₂)(I₃)]⁻. It is a member of a series of mesityltellurenyl anions, which are formed during reactions of (MesTe)₂ with ZnI₂, phenanthroline (phen) and iodine. [Zn(phen)₃][MesTe(I)₂] ( 1 ), [Zn(phen)₃][{MesTe(I)-(I)…Te(I)Mes}{MesTeI₂}] ( 2 ) and [Zn(phen)₃][MesTe(I)(I₂)(I₃)][MesTeI₂] ( 3 ) are isolated depending on the amount of iodine used. The products contain tellurium atoms bonded to a variety of iodine species (I⁻, μ₂-I⁻, I₂ and I₃⁻) and are, thus, perfectly suitable to explore the amphiphilic behavior of tellurium(II) and its relevance for the formation of non-covalent bonds, where tellurium acts as both donor and acceptor simultaneously. The character of chalcogen and halogen bonds are evaluated by the combination of crystallographic data and computational methods.     

The chemical states of tellurium produced by spontaneous fission of252Cf

The distribution of the chemical states of tellurium isotopes produced by²⁵²Cf spontaneous fission, collected separately in the matrixes of NaCl, Kl, NaF, CH₃COONa·3H₂O, Na₂SO₄ and NaNO₃ crystals have been investigated. Two chemical states of tellurium isotopes maintained in these matrixes are Te(IV) and Te(VI). The relationships between the distribution of the chemical states of tellurium isotopes and the produced mode of tellurium, the chemical properties of collection matrixes, the time for collecting fission fragments are studied and the possible mechanism of the interactions of the fission products and the matrixes is discussed. The results show that the distribution of chemical states of tellurium isotopes depends on the chemical properties of the collection matrixes mainly.     

Eigenschaften von Chalkogen-Chalkogen-Bindungen. XII. Reversible Tellurierung von Tetraisopropyldiphosphan; Stabilisierung von Tellurobis(diisopropylphosphan) als Tetracarbonylchromkomplex

Properties of Chalcogene-Chalcogene Bonds. XII. Reversible Telluration of Tetraisopropyldiphosphane, Stabilisation of Tellurobis(diisopropylphosphane) as Tetracarbonylchromium Complex Tetraisopropyldiphosphane 1 reacts with elemental tellurium by tellurium atom insertion to give tellurobis(diisopropylphosphane) 2. 2 is also available from sodium telluride with chlorodiisopropyl phosphane. ^lH, ^l3C, ^3lP and ^l25Te n.m.r. spectra confirm that in solution 2 is in an equilibrium with the educt 1 and elemental tellurium. Reaction of this equilibrium mixture with tetracarbonyl(norbornadiene)chromium(0) provides tetracarbonyl[tellurobis(diisopropylphosphane)]-chromium(0) 3. 3 was isolated in pure state as stable compound; different from 2,3 does not suffer from loss of tellurium at room temperature.     

Darstellung und Kristallstruktur von CsTe4

Preparation and Crystal Structure of CsTe₄ CsTe₄ results from a melting reaction at 570°C in sealed quartztubes. The starting materials Cs and Te in the molar ratio 1:4 are produced in a first step by controlled decomposition of the CsN₃ from mixtures of CsN₃ and Te (1:4) at 350°C. CsTe₄ is monoclinic, space group P2₁/c, with a = 7.857(1) Å, b = 7.286(1) Å, c = 14.155(2) Å, β = 93.83(1)°, and Z = 4. The tellurium atoms form a two-dimensional puckered layer built of from pseudo-trigonal-bipyramidal, T-shaped units Te₄^?. The central tellurium atom of this unit may be considered as a pseudo iodine. The compound is compared with other tellurides MTe_n having some like that unexpected principles of connection.     

Syntheses, crystal structures and optical properties of the first strontium selenium(IV) and tellurium(IV) oxychlorides: Sr3(SeO3)(Se2O5)Cl2 and Sr4(Te3O8)Cl4

Two new quaternary strontium selenium(IV) and tellurium(IV) oxychlorides, namely, Sr₃(SeO₃)(Se₂O₅)Cl₂ and Sr₄(Te₃O₈)Cl₄, have been prepared by solid-state reaction. Sr₃(SeO₃)(Se₂O₅)Cl₂ features a three-dimensional (3D) network structure constructed from strontium(II) interconnected by Cl⁻, SeO₃²⁻ as well as Se₂O₅²⁻ anions. The structure of Sr₄(Te₃O₈)Cl₄ features a 3D network in which the strontium tellurium oxide slabs are interconnected by bridging Cl⁻ anions. The diffuse reflectance spectrum measurements and results of the electronic band structure calculations indicate that both compounds are wide band-gap semiconductors.     

Determination of bismuth, selenium and tellurium in nickel-based alloys and pure copper by flow-injection hydride generation atomic absorption spectrometry—with ascorbic acid prereduction and cupferron chelation-extraction

Diverse matrix effects on the determination of bismuth, selenium and tellurium (μg g⁻¹) in nickel-based alloys and pure copper by flow-injection hydride generation atomic absorption spectrometry (FIAS-HGAAS) were investigated. Sodium tetrahydroborate was used as the reductant. The separation of analytes from copper matrix was mandatory while the analytes were successfully determined without being separated from the alloy matrix. Hydrochloric acid was effective in the prereduction of bismuth and selenium, however, it did not give any satisfactory result for tellurium in nickel-based alloys. In this work, 5% (w/v) ascorbic acid was proved effective for the prereduction of tellurium.Successful determination of tellurium in copper was achieved when N-nitroso-N-phenylhydroxylamine (cupferron) chelation-extraction was employed for the separation of tellurium from copper matrix. Cupferron chelation-extraction was performed in phosphate buffer (a mixture of 0.2 mol l⁻¹ sodium phosphate and 0.1 mol l⁻¹ citric acid). Lanthanum hydroxide coprecipitation at pH 10.0±0.5 was effective for bismuth and selenium. Standard reference materials of nickel-based alloys and pure copper were analyzed using the proposed methods. The linear range for the calibration curves were 0.30-15 and 0.20-10 ng ml⁻¹ for BiH₃ and H₂Se, respectively, with a correlation coefficient of 0.9995. For H₂Te, the linear range for the calibration curves was 0.50-12 ng ml⁻¹ with the correlation coefficient of 0.9994. Good agreement was obtained between experimental values and certified values. Satisfactory recovery ranged from 91±1 to 106±2% was obtained from five replicate determinations.     

Über Chalkogenidhalogenide des Kupfers

Nine ternary chalcogenidehalides of copper could be synthesized under hydrothermal conditions from the resp. hydrogen halide solutions. They belong to the pseudobinary systems, formed between selenium and tellurium and the resp. Cu^I halide. In the selenium systems exist: CuISe₃, rhombohedral; CuBrSe₃, orthorhombic, and CuClSe₂, monoclinic. Two homologous series of tellurium compounds exist: CuXTe, tetragonal, and CuXTe₂, monoclinic (X ? Cl, Br, I). Thermodynamic data could be obtained for the selenium compounds using the Knudsen effusion method. The samples exhibit a temperature independant diamagnetism. All compounds can also be synthesized by reaction of stoichiometric amounts of Cu^I halide and selenium (300°C) or tellurium (350°C). The corresponding thiohalides could not be observed.     

Electrochemistry of tellurium(IV) in KCl−AlCl3 melts

The reduction of Te(IV) at tungsten electrodes in basic and neutral KCl?AlCl₃ melts has been studied in the temperature range from 300 to 400°C using cyclic voltammetry and differential pulse polarography. In basic melts Te(IV), present as TeCl₆^2? and TeCl₅^?, is reduced to soluble Te(II) species, which can be further reduced to elementary tellurium insoluble in tungsten. The divalent species are stabilized by increasing the temperature. From the pCl^? dependence of the reduction process, Te(II) in basic melts is suggested to be present as TeCl₃^? and TeCl₂. In neutral melts a third oxidation state (possibly monovalent tellurium) is formed when Te(II) is reduced.     

Reuse of decayed tellurium dioxide target for production of iodine-131

Iodine-131 was generated by irradiation of natural tellurium dioxide in a nuclear reactor. After irradiation the tellurium dioxide was transferred to hot cell and heated in a quartz furnace at ~700 °C. The Iodine-131 was distilled and collected in carbonate/bicarbonate buffer and used for thyroid cancer patients. The tellurium dioxide used was >99 % pure. During nuclear reaction nanogram tellurium was consumed to produce ¹³¹I, although significant loss of target material may occur in heating process. In dry distillation technique no chemical was added to irradiated target material. After ¹³¹I separation tellurium dioxide was decayed for 8 years in radioactive waste management facility. The decayed TeO₂ was recovered, melted and crushed for desired mesh size. The TeO₂ was sealed in Al capsule for re-irradiation purposes. The separation of ¹³¹I was carried out via dry distillation. The purity and yield of ¹³¹I separated from both of the irradiated new and irradiated re-used tellurium dioxide targets were comparable.