- Solventless and mild procedure to prepare organotellurium(IV) compounds under microwave irradiation
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Tellurium(IV) tetrachloride, p-methoxyphenyltellurium trichloride and the corresponding products of its reaction with alkynes were prepared under very mild reaction conditions, in absence of organic solvents and in short reaction times all assisted by mic
- Princival, Cleverson,Dos Santos, Alcindo A.,Comasseto, Jo?o V.
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- Synthesis and crystal structure of Te6[MCl6] (M = Zr, Hf), containing a polymeric chalcogen cation (Te62+) n
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The reaction of tellurium, tellurium tetrachloride, and ZrCl4 or HfCl4, respectively, under the conditions of chemical vapour transport in a temperature gradient 220 → 200°C yields black crystals of Te6[ZrCl6] and Te6[HfCl6]. While Te6[ZrCl6] is formed almost quantitatively, Te 6[HfCl6] is always accompanied by neighbored phases such as Te4[HfCl6] and Te8[HfCl6]. The crystal structures of Te6[ZrCl6] (orthorhombic, Pbcm, a = 1095.4(1), b = 1085.2(1), c = 1324.5(1) pm) and Te6[HfCl6] (a = 1094.8(2), b = 1086.3(2), c = 1325.0(2) pm) are isotypic and consist of one-dimensional polymeric (Te62+)n cations and of discrete, only slightly distorted octahedral [MCl6]2- anions (M = Zr, Hf). The cations are build of five membered rings which are connected via single Te atoms to a polymer -Te-Te5-Te-Te 5-. Out of the six Te atoms of the asymmetric unit of the chain four atoms exhibit two bonds and two atoms exhibit three bonds. The connecting, threefold coordinated Te atoms of the five membered rings carry formally the positive charges. In consistence with the assumption of the presence of throughout localized bonds eH band structure calculations for Te 6[ZrCl6] show semiconducting behaviour with a band gap of 1.8 eV.
- Baumann, Alexander,Beck, Johannes
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- Modified tellurium subhalides in the new structure type [Te15X4]n[MOX4]2n (M = Mo, W; X = Cl, Br)
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The reactions of Te2Br with MoOBr3, TeCl4 with MoNCl2/MoOCl3, and Te with WBr5/WOBr3 yield black, needle-like crystals of [Te15X4][MOX4]2 (M = Mo, W; X = Cl, Br). The crystal structure determinations ([Te15Br4][MoOBr4]2: monoclinic, Z = 1, C2/m, a = 1595.9(4) pm, b = 403.6(1) pm, c = 1600.4(4) pm, β = 112.02(2)°; [Te15Cl4][MoOCl4]2: C2/m, a = 1535.3(5) pm, b = 402.8(2) pm, c = 1569.6(5) pm, β = 112.02(2)°; [Te15Br4][WOBr4]2: C2, a = 1592.4(4) pm, b = 397.5(1) pm, c = 1593.4(5) pm, β = 111.76(2)° show that all three compounds are isotypic and consist of one-dimensional ([Te15X4]2+)n and ([MOX4]-), strands. The structures of the cationic strands are closely related to the tellurium subhalides Te2X (X = Br, I). One of the two rows of halogen atoms that bridges the band of condensed Te6 rings is stripped off, and additionally one Te position has only 15% occupancy which leads to the formula ([Te15X4]2+)n (X = Cl, Br) for the cation. The anionic substructures consist of tetrahalogenooxometalate ions [MOX4]- that are linked by linear oxygen bridges to polymeric strands. The compounds are paramagnetic with one unpaired electron per metal atom indicating oxidation state Mv, and are weak semiconductors. Johann Ambrosius Barth 1996.
- Beck, Johannes,Pell, Michael A.,Richter, Juergen,Ibers, James A.
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- Study of the temperature effect on the process of rubidium hexachlorotellurite decomposition
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Thermal dissociation of rubidium hexachlorotellurite in inert atmosphere (argon) and in atmosphere with air access was studied. The DTG and DTA curves for the process of rubidium hexachlorotellurite thermal dissociation in the argon atmosphere are given. Their character is defined by the behavior of TeCl4, which is liberated on the decomposition of samples.
- Lyakh,Sizyakov,Zaitsev,Pigova,Ugolkov
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- Synthesis of the titanium phosphide telluride Ti2PTe2: A thermochemical approach
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The phosphide telluride Ti2PTe2 can be synthesised from the elements or from oxides in a thermite type reaction. Both ways have been optimised by consideration of the thermodynamic behaviour of the compound. Hence, the investigation of phase equilibria in the ternary system Ti/P/Te and of the thermal decomposition of Ti2PTe2 was necessary. This investigation was performed by using different experimental approaches as total pressure measurements, thermal analysis and mass spectrometry. The results were supported and further analysed by thermodynamic modelling of the ternary system. It was shown that Ti2PTe2(s) decomposes to Ti2P(s) and Te2(g) in six consecutive steps. The growth of single crystals of Ti2PTe2 is thermodynamically described as a chemical vapour transport with TiCl4(g) acting as the transport agent.
- Philipp, Frauke,Schmidt, Peer,Milke, Edgar,Binnewies, Michael,Hoffmann, Stefan
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- Fabrication of arsenic selenide optical fiber with low hydrogen impurities
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Arsenic selenide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of 0.1 wtpercent tellurium tetrachloride (TeCl4) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to give very low H-Se impurity content. Consequently, the H-Se absorption band centered at 4.57 μm has been reduced from tens of dB/m to 0.2 dB/m.
- Nguyen, Vinh Q.,Sanghera, Jas S.,Pureza, Pablo,Kung, Frederic H.,Aggarwal, Ishwar D.
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- 2-Thiophenyltellurium derivatives: Alternative synthetic routes and structural characterization
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Grignard reagent prepared from 2-thiophenyl bromide in THF consumes elemental tellurium readily at room temperature and provides a route to obtain bis(2-thiophenyl)ditelluride, Tpn2Te2 (1, Tpn = 2-C 4H3S) in goo
- Chauhan, Ashok K.S.,Singh, Poornima,Srivastava, Ramesh C.,Butcher, Ray J.,Duthie, Andrew
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- Heavy atom analogues of 1,2,3-dithiazolylium salts: Preparation, structures and redox chemistry
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Synthetic routes to salts of the benzo[1,2,3]thiatellurazolylium cation [2c]+ and its selenium analogue [2b]+ are described. Access to the cation frameworks involves the intermediacy of N,N,S-trisilylated 2-aminobenzenethiol. The latter reacts smoothly with selenium and tellurium halides ECl4 (E = Se, Te) to afford the desired heterocyclic benzo cations [2b]+ and [2c]+ as their chloride salts. Anion exchange provides the corresponding GaCl4-, OTf - and TeCl5- salts of [2c]+, all of which have been characterized by X-ray crystallography. While the gallate salts of the sulfur and selenium cations [2a]+ and [2b]+ crystallize as ion-paired cations and anions, salts of [2c]+ adopt solid-state structures that display strong association of the cations via short intermolecular Te-N′ bonds. However, crystallization of [2c]+ salts in dichloroethane in the presence of GaCl3 leads to cleavage of the dimers and the formation of a Lewis acid adduct at nitrogen. Reduction of the benzo cations [2a,b]+ affords the respective radicals 2a,b, both of which have been characterized by electron paramagnetic resonance (EPR) spectroscopy. Attempts to generate the corresponding radical 2c have been unsuccessful, although a material of nominally correct elemental composition can be generated by chemical reduction. The energetics of association of [2a,b,c]+ in solution has been probed by means of density functional theory calculations using the polarized continuum model. The results suggest that the dimeric nature of the Te-centered cation is retained in solution. The strength of the interaction is, however, less than in N-alkylated tellurodiazolylium salts.
- Risto, Maarit,Assoud, Abdeljalil,Winter, Stephen M.,Oilunkaniemi, Raija,Laitinen, Risto S.,Oakley, Richard T.
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p. 10100 - 10109
(2009/05/15)
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- Thermal transformations of gold(III) complexes with chalcogen tetrachlorides
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Thermal transformations of chalcogen chloride complexes of gold(III) of the AuCl3L type (L = SCl4, SeCl4, TeCl 4) have been investigated in the temperature range of 20-500°C. The melting points are found to be 108°C for AuCl3SCl 4, 153°C for AuCl3TeCl4, and 201°C for AuCl3SeCl4. For decomposition according to the scheme AuCl3L → AuCl3 + L, the thermal stability sequence of the complexes is AuCl3SCl4 3SeCl 4 3TeCl4 (133, 260, and 340°C, respectively). The role of gold trichloride → gold monochloride thermolysis and its dependence on the presence of chlorine vapor are demonstrated. The presence of chlorine vapor widens the temperature region of existence of AuCl3 and raises the gold monochloride → metallic gold thermolysis end temperature. The general scheme of thermal transformations of chalcogen chloride complexes of gold(III) is given: AuCl3L (s) →T1 AuCl3L(l) →-LT2 AuCl3(s) →-Cl2 T3 AuCl(s) →-Cl2T4 Au (s). Therefore, the thermal decomposition of AuCl3L complexes proceeds with the sequential reduction of gold: Au(III) → Au(I) → Au(0).
- Volkov,Fokina,Pekhn'o,Yanko
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p. 121 - 124
(2008/10/08)
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- Chemical transport of solid solutions: Mixed spinels
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Chemical vapor transport is a suitable pathway to controllable syntheses of mixed spinel systems. Solid solutions of spinels on the basis of 3d transition metal oxides and gallium oxide can be prepared using various transport agents (TeCl4, Cl2, HCl). Transport processes observed are consistent with theoretical predictions.
- Patzke, Greta R.,Binnewies, Michael
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- Trans-PdBr2(SeBr2)2 and cis-PdBr2(TeBr2)2 - New complexes of palladium with chalcogenodibromides as ligands
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Dark red crystals of the air-stable compound PdSe2Br6 are formed by reaction of the elements in CCl4 at 180°C in sealed silica ampoules. They show triclinic symmetry with space group P1 and lattice constants a = 4.536(1) A, b = 7.238(1) A, c = 8.856(2) A, α = 105.40(3)°, β = 97.86(3)°, γ = 94.50(3)°. The crystal structure is composed of isolated trans-PdBr2(SeBr2)2 molecules which occupy inversion centres. Black crystals of the air-stable compound PdTe2Br6 are formed by reaction of Pd, Te, and TeBr4 in CCl4 at 200°C in sealed silica ampoules. They show monoclinic symmetry with space group P 21/c and the lattice constants a = 15.513(3) A, b = 8.855(2) A, c = 18.092(4) A, β = 114.72(3)°. The crystal structure is composed of cis-PdBr2(TeBr2)2 molecules piled up in the shape of a hexagonal rod packing. Within the piles centrosymmetric dimers are built up with unusual short intermolecular distances Pd-Pd and Te-Br. The structure relations of the hitherto known compounds PdX2(EX2)2 with E = S, Se, Te and X = Cl, Br are discussed.
- Neininger, Klaus,Rotter, Heinz Wilhelm,Thiele, Gerhard
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p. 710 - 718
(2008/10/09)
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- Synthesis, Structures and Properties of CF3S-Substituted Tellurium Compounds
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New preparations for the following compounds are described: Te(SCF3)2, Te(NSO)2, and Cl2Te(NSO)2.The catalytic or thermal SO2 elimination from Cl2Te(NSO)2 affords a coordinated or non-coordinated thiachalcogenadiazole.Conversions of these compounds are reported.Evidence for the proposed mechanism for the reaction between Te(NSO)2 and SbCl5 is provided.Cl4Te2N2(SCF3)2, prepared from TeCl4 and CF3SN(SiMe3)2, reacts with LiN(SiMe3)2 to form 4Te2N2(SCF3)2.An X-ray structural analysis of Cl4Te2N2(SCF3)2 is presented. - Key Words: Tellurium, bis(sulfinylamido)-, bis(trifluoromethylthio)- / Thiachalcogenadiazole / Ditelluradiazetidine
- Boese, Roland,Dworak, Juergen,Haas, Alois,Pryka, Michael
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p. 477 - 480
(2007/10/02)
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- Some investigations of the chemistry of tellurium chloride pentafluoride, its reaction with caesium fluoride, and the preparation of cis and trans methoxytellurium(VI)chloride tetrafluoride, (CH3O)TeClF4
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The reaction of TeClF5 with CH3OH, and CH3OSiMe3, leads to a mixture of cis- and trans-(CH3O)TeClF4 in a ratio of 1:6, as well as some unidentified Te(IV) product.The vibrational spectrum of the 1:6 mixture of cis- and trans-(CH3O)TeClF4 was accounted for on the basis of the predominant pseudo-C4v trans isomer.TeClF5 is unreactive towards anhydrous HF, SbF5, AlCl3, SO2, F2, and ClF at room temperature.Over the temperature range 70-250 deg C it thermally decomposes to TeF6, TeF4, and Cl2.It slowly reacts with CsF to form CsTeF5, TeF6, Cl2, and small amounts of ClF, and with HNMe2 it is also reduced to form TeF4*HNMe2.
- Lawlor, Lawrence J.,Passmore, Jack
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p. 1477 - 1482
(2007/10/02)
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- Te6O11Cl2(s) +.
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The thermal decomposition products from Te//6O//1//1Cl//2(s) were identified and studied by mass spectrometric methods. The appearance potentials for several of the ion species observed were determined from these studies and TeOCl** plus was found to be a fragment of TeOCl//2. The temperature dependences of several of these ions were studied and gave support to the identification of TeOCl** plus as a fragment since the slopes of the TeOCl//2** plus and TeOCl** plus intensities versus temperature were parallel. The slopes of the TeCl//2** plus and TeCl** plus intensities versus temperature were also parallel, as were the slopes for TeCl//4** plus , TeCl//3** plus , and HgCl//2** plus , which suggest that the ions in each group may arise from a common molecule.
- Cunningham,Ames
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p. 163 - 186
(2008/10/08)
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