- Stability limits and properties of Tl2TeBr6, Cs 2TeBr6, and Rb2TeBr6
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The composition stability limits of the compounds Tl2TeBr 6, Cs2TeBr6, and Rb2TeBr6 were determined from differential thermal analysis, microstructural, and microhardness data. The congruen
- Peresh,Zubaka,Kun,Galagovets,Barchii,Sabov
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- Synthesis, structure, and properties of the tantalum-rich suicide chalcogenides Ta15Si2QxTe10-x (Q = S, Se)
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The quaternary tantalum suicide chalcogenides Ta15Si2QxTe10-x (Q = S, Se) are accessible from proper, compacted mixtures of the respective dichalcogenides, silicon and elemental tantalum at 1770 K in sealed molybdenum tubes. The structures were determined from the strongest X-ray intensities of fibrous crystals with cross sections of about 3 μm and confirmed by fitting the profile of single phase X-ray diffractograms. The phases Ta15Si2S3.5Te6.5 and Ta15Si2. Se3.5Te6.5 crystallize in the monoclinic space group C2/m with two formula units per unit cell, a = 2393.7(1) pm, b = 350.08(2) pm, c = 1601.2(1) pm, β = 124.700(4)°, and a = 2461.3(2) pm, b = 351.70(2) pm, c= 1601.7(1) pm, β = 124.363(5)°, respectively. Tri-capped trigonal prismatic Ta9Si clusters stabilized by encapsulated Si atoms can be seen as the characteristic unit of the structure. The clusters are fused into twin columns which are connected by additional Ta atoms, thus forming corrugated layers. The remaining valences at the surfaces of the layered Ta-Si substructure are saturated by those of chalcogen atoms which are coordinated only from one side by three, four or five Ta atoms. Few bridging covalent Ta-S-Ta and Ta-Se-Ta bonds and, otherwise, dispersive interactions between the Q atoms hold these nearly one nanometer wide slabs together. The phases are moderate metallic conductors. There is no evidence for any electronic instability within 10-310 K in spite of the high anisotropy of the structures. Wiley-VCH Verlag GmbH, 2001.
- Debus, Stephan,Harbrecht, Bernd
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- Solvothermal synthesis and crystal structure of Te8[U2Br10], containing a polymeric chalcogen cation (Te82+)n
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Under solvothermal conditions, the reaction of Te, TeBr4 and UBr5 in SiBr4 at 200°C yields Te8[U2Br10] as silvery crystals. The crystal structure (triclinic, P1, a = 900.8(4), b = 1205.1(5), c = 1366.0(6) pm, α = 80.93(4)°, β = 76.83(3)°, γ = 78.84(3)°, Z = 2) is built of one-dimensional polymeric (Te82+)n cations consisting of boat-shaped Te6 rings, which are linked by Te2 bridges. The anions [U2Br102-]n are also polymeric, consisting of edge sharing UBr7 pentagonal bipyramids [UBr3Br4/22-]n and contain U(IV). Both chains are parallel to each other and run along the crystallographic a-axis. The cation represents a formerly unknown isomer of Te82+ ions. So far, Te82+ has been known as molecular clusters in Te8[MCl6] (M = Zr, Hf, Re) and (Te8)(Te6)[WCl6]4, or in form of linked bicyclic monomers that are present in Te8[WCl6]2. A polymeric chain-like form closely related to Te8[U2Br10] was found in Te8[Bi4Cl14].
- Beck,Fischer
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p. 369 - 372
(2008/10/08)
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- π-Complexes of Tellurium Tetrabromide with Aromatic Hydrocarbons in Extraction from Sulfate-Bromide Media
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Extraction and electron spectroscopy were used to establish that π complexes of tellurium tetrabromide with aromatic hydrocarbons (L) of composition TeLBr4 form in the organic phase. Concentration extraction constants for the extraction of TeBr
- Demidova,Tsikoza,Torgov
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p. 1140 - 1144
(2008/10/08)
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- Molybdenum Telluride Triangular Complexes Containing [Mo3(μ3-Te)(μ2-Te2) 3]4+ Cluster Fragments: Synthesis, Structure, and Properties
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The triangular clusters Mo3Te7I4 and Mo3Te7I4 are prepared by heating stoichiometric amounts of molybdenum, tellurium, and iodine. The clusters boiled with aqueous KCN form brown solutions
- Fedin,Fedorov,Imoto,Saito
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p. 1800 - 1810
(2008/10/08)
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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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p. 473 - 478
(2008/10/09)
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