Lanthanoid and yttrium tellurates

Preparation in aqueous medium of all the lanthanoid (except Ce and Pm) and yttrium tellurates is described. Chemical analyses, solubilities at 25°C in water and thermograms of all the products prepared were determined. X-ray diffractograms and DTA and DTG curves of La, Gd and Yb tellurates were obtained and commented. Partial volatilization of lanthanoid is observed in the thermal analysis of tellurates.     

A systematic study of insoluble substances. III

The tungstales of Ni, Co, Cr, Zr. Zn and Cu and the tellurates and vanadates of Cr and Zr, when heated at 800° were found to become sufficiently resistant to the standard acid treatement to be considered insoluble, The tungstates, te tellurates and vanadates of other nietals were not affected by heating.     

Synthesis and crystal structure of new alkali metal hydrogen tellurates

New alkali metal hydrogen tellurates have been synthesized, and their structures have been determined by X-ray crystallography. Hydrogen tellurates I–VI contain centrosymmetric binuclear anions [Te₂O₁₀H_4+x ]^(4?x)?, where x=0, 1, 2. Hydrogen tellurates II and VI contain, in addition to the binuclear anion, mononuclear species [TeO₆H₄]^2? and Te(OH)₆, respectively. The CNs of alkali metals vary from 8 to 12. In all structures, the hydrogen atoms (of both the hydroxy groups and water molecules) are involved in hydrogen bonding.     

Preparation and crystal data for two trimetaphosphate tellurates: Te(OH)6 · 2Na3P3O9 · 6H2O and Te(OH)6 · K3P3O9 · 2H2O

Te(OH)₆ · 2Na₃P₃O₉ · 6H₂O, is hexagonal (P6₃/m) with a = 11,67(1), c = 12,12(1) Å, Z = 2 and D_x = 2,225 g/cm³. Te(OH)₆ · K₃P₃O₉ · 2H₂O, is monoklin (P2₁/c) with a = 19,61(5), b = 7,456(1), c = 14,84(6) Å, = 108,01(4), Z = 4 and D_x = 2,506 g/cm³. Both compounds are the first examples of phosphate tellurates in which the anion phosphate is condensed to the ring anion P₃O₉. As in phosphate tellurates already described the phosphate groups are independent of the TeO₆ octahedra.     

Thermochemical study of gaseous salts of oxygen-containing acids: XXII.<Superscript>1</Superscript> Lead salts

Reactions of gas-phase synthesis of lead phosphates and tellurates have been studied. Standard enthalpies of formation and atomization of gaseous PbPO₂, PbPO₃, PbP₂O₆, PbTeO₃, and Pb₂TeO₄ salts have been determined.     

Reactions of tellurates(IV) of some 2nd group metals with basic oxides

Calcium, strontium and barium tellurates(IV) were heated, in N₂ atmosphere, with stoichiometric amounts of CaO, SrO and BaO, respectively. The products of reactions, proceeding at 380–620°C, contained orthotellurate and telluride anions formed in disproportionation.     

Mechanochemical reactions of telluric acid with alkaline fluorides

The mechanochemical reactions of telluric acid, Te(OH)₆ with alkaline fluorides (Na and K) have been studied using IR and XRD techniques. The reactions lead to the formation of hydrogen-bonding complexes, NaF.Te(OH)₆ and 2KF.Te(OH)₆. The reactions are free from side products such as alkali tellurates, alkali fluorotellurates or HF₂⁻ salts.     

Structural studies and electrical properties of Cs/Al/Te/O phases with the pyrochlore structure

A series of polycrystalline and single crystal cesium aluminum tellurates with the pyrochlore structure have been prepared and characterized. The variations in cell edge for the Cs/Al/Te/O phases range from 10.06 ? for the Al rich limit to 10.14 ? for the Te rich limit. Rietveld structural analyses based on both X-ray and neutron diffraction data were performed on 5 different compositions. Single crystals of 3 compositions were prepared and studied by X-ray diffraction. The anharmonic component of the thermal motion for Cs was small but became significant on replacing Cs with Rb. A maximum in the electrical conductivity of about 0.1 S/cm is found in the middle of this range close to the ideal composition of CsAl(1/3)Te(5/3)O(6). The conductivity is attributed to filled Te 5s states associated with Te(4+) lying just below the conduction band based on empty Te 5s states associated with Te(6+). The relatively large Te(4+) ion is compressed by the lattice, and as this compression increases the filled 5s states approach the conduction band and thereby increases conductivity.     

Lanthanoidtellurate Ln2TeO6

Lanthanoid Tellurates Ln₂TeO₆ The crystal structure of La₂TeO₆, orthorhombic, a = 551.0, b = 944.1, c = 1038.7 pm, and crystallographic data of other isostructural lanthanoid tellurates (up to Yb₂TeO₆) formerly described as hexagonal, have been determined. For a second modification of the Yb compound, the Na₂SiF₆ structure has been confirmed.     

Structural behaviour of alkaline sulfides under compression: high-pressure experimental study on Cs2S

The high-pressure behaviour of cesium sulphide Cs(2)S has been studied up to 19 GPa at room temperature using angle-dispersive x-ray powder diffraction in a diamond-anvil cell. X-ray results show that the initial anticotunnite-type structure (S.G. Pnma) seems to undertake a continuous transformation to a distorted Ni(2)In-type structure (also with S.G. Pnma), starting below 1 GPa and being almost completed at 5 GPa. The profile of the x-ray diffraction patterns did not change noticeably from this pressure to 17 GPa. The observed structural changes in Cs(2)S are discussed in relation to the high-pressure behaviour of the rest of alkaline sulfides and their systematic trends are pointed out. Finally, we discuss the analogies between the structures of alkaline-metal chalcogenides and those of the cationic arrays of their corresponding oxides (sulfates, selenates, and tellurates) comparing the insertion of oxygen and the application of pressure.     

A linear bridging angle in the pyrovanadate group within the crystal structure of Hg2V2Te2O11

The title compound, dimercury(II) divanadium(V) ditellurium(IV) undecaoxide, Hg₂V₂Te₂O₁₁, is a new representative within the family of divalent oxovanadato(V)tellurates(IV). The anionic framework is made up of disphenoidal [TeO₄] polyhedra that are linked by corner‐sharing to two neighbouring pyrovanadate units, resulting in chains of six‐membered rings propagating parallel to [10]. The bridging O atom of the pyrovanadate unit is located on an inversion centre, leading to a staggered conformation and a linear V—O—V angle between the two [VO₄] tetrahedra. The anionic chains are connected by interjacent six‐coordinate Hg²⁺ cations into a three‐dimensional framework. The 5s² lone electron pair of the Te^IV atom is stereochemically active and protrudes into the free space of the chain links.     

Barium-orthotellurat,BaH4TeO6

Zusammenfassung Bei der Umsetzung von Kaliumtellurat mit BaCl₂ fällt primär BaH₄TeO₆, welches bei 250°C 1 1/2 Mole Wasser abgibt und erst bei über 375°C in das wasserfreie BaTeO₄ übergeht. Vergleiche der Pulverdiagramme dieser Bariumtellurate untereinander und mit denen von BaSeO₄ und BaSO₄ werden angestellt.

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BaH₄TeO₆ is precipitated when barium chloride is added to a solution of potassium tellurate. This compound looses 1 1/2 moles water when heated to 250°C, and forms BaTeO₄ above 375°C. TheDebye-Scherrer powder diagrams of these barium tellurates are compared with each other, and with those of BaSeO₄ and BaSO₄.

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Mit 3 Abbildungen

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Frau Professor Dr.Erika Cremer anläßlich ihres Geburtstages 1965 in Verehrung gewidmet.     

Perfluoroalkyl(dithiocarbamato) tellurium(II) compounds

[NMe(4)][R(f)Te(SC(S)NR(2))(2)] derivatives are selectively formed by the oxidation of [NMe(4)]TeR(f) (R(f) = CF(3), C(2)F(5)) with [R(2)NC(S)S](2) (NR(2) = NEt(2), NBz(2), N(CH(2))(4)) in almost quantitative yields. An alternative route to obtain the dithiocarbamato complex anions offer reactions of Te[SC(S)NR(2)](2) (NR(2) = NEt(2), NBz(2)) with equimolar amounts of Me(3)SiR(f) and [NMe(4)]F. Some of the derivatives were recrystallized with bulky cations in order to determine the crystal structures. Structural elucidation by diffraction methods exhibit the structural feature of a distorted pentagonal planar environment (resembling "butterflies") around the tellurium centres. The carbamato tellurates can be transferred easily into the neutral derivatives, R(f)TeSC(S)NR(2), upon treatment with Ag[BF(4)]. In solution they equilibrate with Te(2)(R(f))(2) and [R(2)NC(S)S](2) and finally are transformed into Te(R(f))(2), Te[SC(S)NR(2)](2), and Te[SC(S)NR(2)](4), respectively. All compounds are fully characterized by NMR spectroscopic methods ((1)H, (13)C, (19)F, (125)Te). Additionally, synthesis and characterization of the hitherto unknown derivative [NMe(4)]TeC(2)F(5) are described.     

Perfluoralkyltellur-Verbindungen: Untersuchungen zur Bildung von [(CF3)2TeX]+-Kationen und [(CF3)2TeX2+n]n−-Anionen (X = F,Cl, Br)

Perfluoroalkyl Tellurium Compounds: Investigations of the Preparation of [(CF₃)₂TeX]⁺ Cations and [(CF₃)₂TeX_2+n]^n? Anions (X = F, Cl, Br) The reactions of (CF₃)₂TeF₂ with BF₃, AsF₅ and SbF₅ yield the new complex compounds [(CF₃)₂TeF][BF₄] and [(CF₃)₂TeF][EF₆], respectively, while during the reactions of (CF₃)₂TeX₂ (X = Cl, Br) with halide acceptors only decompositions take place. (CF₃)₂TeX₂ form with MX (X = F, Cl; M = K, Rb, Cs, Me₄N, Ag) the isolable salts of the composition M[(CF₃)₂TeX₃]. M[(CF₃)₂TeBr₃] is only detected in solution besides decomposition products. No evidence for the formation of hexa-coordinated tellurates(IV) M₂[(CF₃)₂TeX₄] is found.     

Vibrational spectra of tellurates with the garnet structure

The IR and Raman spectra of tellurates Ln₃Te₂Li₃O₁₂ (Ln=Pr…Lu, Y), Ca₃Te₂Zn₃O₁₂ and Na₃Te₂M³⁺₃O₁₂ (M³⁺ = Al, Ga, Fe) with the garnet structure are presented and discussed on the basis of a group theoretical analysis, and of ⁶Li—⁷Li isotopic frequency shifts. The assignment of the high-frequency bands to stretching vibrations of the TeO₆ octahedra is only an approximation whose validity depends on the nature of the tetrahedral cation (Li, Zn or M³⁺) and of the symmetry properties of the vibrations: cationic mass effects play an important role in the antisymmetric, IR-active vibrations, whereas the bonding forces are the determining factor in the totally symmetric, Raman active vibrations. For the Na₃Te₂M³⁺₃O₁₂ garnets, the (TeO₆) internal modes approximation is unacceptable since the stretching frequencies of the TeO₆ and M³⁺O₄ groups are of the same order of magnitude. No detailed assignments are available for the medium-frequency bands: they are due in part to the bending vibrations of the TeO₆ octahedra, but the contribution of the tetrahedral cation Zn²⁺ or M³⁺ to this region of the spectrum remains largely unknown. The translational frequencies of the dodecahedral Ln³⁺ cations have been identified in the low frequency region (below 250 cm⁻¹) by comparison of the frequencies of the Ln and Y garnets.     

Thermal Dehydration and Decomposition of Oxygen-tellurium(VI) Compounds with Alkali Metals and Ammonium

In the framework of a systematic study of compounds with hydrogen bonds, thermoanalitycal methods were employed to study four groups of hydrogen tellurates: a) Li₂H₄TeO₆·3H₂O, Na₂H₄TeO₆, K₂H₄TeO₆; b) LiH₅TeO₆, NaH₅TeO₆·2H₂O, KH₅TeO₆·2H₂O; c) NH₄HTeO₄; d) K₄H₄Te₂O₁₀·7.3H₂O. The individual steps in the thermal degradation were described and the intermediates formed were characterized by analytical, infrared spectrometry, powder X-ray and, for NH₄HTeO₄, also mass spectrometry methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Prokaryotic Expression, Purification, Antibody Production of a NH2 -Terminal Fragment of mCLCA3 Protein and Analysis of mClCA3 Protein Expression in Asthmatic Mouse Lung

mCLCA3 is a member of calcium activated chloride channel(CACC)family that may play an important role in mucin packaging and secretion in asthmatic and cystic fibrosis lung.To study the protein structure and expression of mCLCA3 in asthmatic mouse lung,an N-terminal 269 amino acid peptide of mCLCA3 was expressed in E.coli,purified to homogeneity and rabbit polyclonal antibodies against this peptide were generated.Immunohistochemistry of asthmatic mouse lung using the antibody indicated exclusive mCLCA3 expression in mucin granules of goblet cells in airway surface and lumen.Immunoblot analysis of lavage fluid from asthmatic mouse lung revealed a single 90 kDa protein form of mClCA3.The results demonstrate that the 90 kDa N-terminal peptide,neither the full-length protein nor the reported N-terminal 35 kDa cleaved form of mClCA3 is the major functional form involved in the packaging and exocytosis of mucin granules in asthmatic goblet cells.     

Evaluation of 3H-paroxetine as a radioligand for in vivo study of 5-hydroxytryptamine uptake sites in mouse brain

The distribution of radioactivity in the mouse brain after intravenous administration of 3H-paroxetine was in the order (highest to lowest) hypothalamus greater than cerebral cortex greater than cerebellum. The radioactivity in the hypothalamus and cerebral cortex after injection of 3H-paroxetine was significantly decreased by treatment with 6-nitroquipazine or paroxetine. HPLC and TLC analyses show that no radioactive metabolites were found in the mouse brain 3 h after intravenous administration of 3H-paroxetine. The present results indicate that 3H-paroxetine would be a suitable radioligand for in vivo study of 5-HT uptake sites in mouse brain.     

From esoteric theory to therapeutic antibodies

Theoretical analyses of amino acid and nucleotide sequences of immunoglobulins have provided a unique approach to the understanding of structure and function of antibodies. Variability plots unambiguously identified that the antibody-combining site is formed by six short complementarity determining regions (CDRs), three each from light and heavy chains. Since three-dimensional (3-D) foldings of framework regions (FRs) are similar among different antibodies, the 3-D configurations of CDRs from a specific antibody can be predicted based on their amino acid sequences. The resulting structure forms a compact surface that fits the antigen molecule tightly. The third CDR of the heavy chain (CDRH3), which is coded by the D-minigene together with the N- and/or P-segments, appears to play a unique role in fine fitting between antibody and antigen molecules. In order to maintain biological activities, the grafting of mouse CDRs onto human FRs should closely match the human FR amino acid sequences with the original mouse antibody. Similarities between human and mouse FR sequences that have been preserved for over 20 million years of evolution can be a useful tool in humanizing mouse antibodies.     

Studies on thermophile products. V. Immunosuppressive profile in vitro of Bacillus stearothermophilus component, Fr.5-B.

The immunosuppressive profile of Bacillus stearothermophilus UK563 component, Fr.5-B, is presented in in vitro studies. Fr.5-B (0.1-1000 ng/ml), provided it was added at the initiation of mixed leukocyte reaction (MLR), inhibited dose-dependently the incorporation of tritiated thymidine ([3H]TdR) into mouse spleen cells and human peripheral blood lymphocytes. Even the addition of Fr.5-B 48 h after the onset of culture suppressed mouse MLR, unlike cyclosporin A (CYA). Fr.5-B significantly inhibited cytotoxic T lymphocyte generation determined by [3H]TdR-release micro-cytotoxicity assay by using mouse mastocytoma P815 as targets. Moreover, this component decreased dose-dependently the expression of class II major histocompatibility molecules (Ia) on mouse peritoneal macrophages induced by concanavalin A supernatant. The present results revealed the unique immunosuppressive property of Fr.5-B which was different from that of CYA.