Die Kristallstruktur von Li2TeO3

Crystal Structure of Li₂TeO₃ Crystals of Li₂TeO₃ were prepared from melts. Li₂TeO₃ crystallizes in the monoclinic system, space group C2/c. The lattice parameters are a = 5.06₉, b = 9.56₆, c = 13.72₇ Å, β = 95.4°. The formular unit is 8. The crystal structure has been determined by Patterson and threedimensional differential Fourier synthesis refined by least squares using isotropic temperature corrections. The final R-value of 772 observed reflections is 0.101. Li₂TeO₃ forms a layer lattice consisting of trigonal TeO₃ pyramids and deformed LiO₄ tetrahedrons. The TeO₃ pyramids are only connected with the corners of LiO₄ groups, which are linked one with another by common corners and edges.     

Ein Oxotellurat (VI) neuen Typs: Rb6[TeO5] [TeO4]

A New Type of Oxotellurates (VI): Rb₆[TeO₅] [TeO₄] For the first time single crystals of Rb₆Te₂O₉ was obtained by annealing intimate mixtures of the binary oxides (closed Ag-cylinder in supremax-glass ampoule, 680°C, 45 d). The structure elucidation (four-circle diffractometer, AgKα, 2083 I₀(hkl); R = 9.5%, R_w = 6.6%) confirms the space group C2/c with a = 1207.5(7), b = 1266.3(5), c = 1105.3(6) pm, β = 123.1(1)⁰, Z = 4 (Guinier-Simon photographs). Characteristic for this structure are ?isolated”? trigonal bipyramidal groups of [TeO₅] and ?isolated”? tetrahedral groups of [TeO₄], so we prefere to name the new compound Rb₆[TeO₅][TeO₄]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, the latter derived from Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

Preparation,Thermal Behaviour and Crystal Structure of the Basic Mercury(II) Tetraoxotellurate(VI), Hg2TeO5, and Redetermination of the Crystal Structure of Mercury(II) Orthotellurate(VI), Hg3TeO6

Single crystals of Hg₂TeO₅ were obtained as dark‐red parallelepipeds by reacting stoichiometric amounts of Hg(NO₃)₂ · H₂O and H₆TeO₆ under hydrothermal conditions (250 °C, 10d). The crystal structure (space group Pna2₁, Z = 4, a = 7.3462(16), b = 5.8635(12), c = 9.969(2)Å, 1261 structure factors, 50 parameters, R[F² > 2σ(F²)] = 0.0295) is characterized by corner‐sharing [TeO₆] octahedra forming isolated chains [TeO_4/1O_2/2] which extend parallel to [100]. The two crystallographically independent Hg atoms are located in‐between the chains and interconnect the chains via common oxygen atoms. Amber coloured single crystals of Hg₃TeO₆ were prepared by heating a mixture of Hg, HgO and TeO₃ together with small amounts of HgCl₂ as mineralizer in an evacuated and sealed silica glass tube (520 °C). The previously reported crystal structure has been re‐investigated by means of single crystal X‐ray data which reveal a symmetry reduction from Ia3¯d to Ia3¯ (Z = 16, a = 13.3808(6) Å, 609 structure factors, 33 parameters, R[F² > 2σ(F²)] = 0.0221). The crystal structure is made up of a body‐centred packing of [TeO₆] octahedra with the Hg atoms situated in the interstices of this arrangement. Upon heating, both title compounds decompose in a one‐step mechanism under formation of TeO₂ and loss of the appropriate amounts of elementary mercury and oxygen.     

Disilberoxotellurat(VI), Ag2TeO4

Disilver Oxotellurate(VI), Ag₂TeO₄ Ag₂TeO₄ was synthesised by reaction of Ag₂O and TeO₂ applying an elevated oxygen pressure. According to a single crystal structure determination (C2/c, a = 9.0588(9), b = 9.2456(8), c = 13.623(1) Å, β = 91.758(8)°, Z = 12, 1289 independent reflections, R1 = 2.32 %, wR2 = 5.51 %), Ag₂TeO₄ contains a novel chain‐like polyanion with tellurium in an octahedral coordination. The TeO₆ octahedra are connected via common edges and vertices in a way that the resulting polyanion represents a section of the rutile structure type. Ag₂TeO₄ shows diamagnetic and insulating behaviour, it decomposes at 560 °C into Ag₂TeO₃ and oxygen.     

Crystal structure of a new gallium tellurite: Ga2Te4O11

Ga₂Te₄O₁₁ crystallises with triclinic symmetry (space group P1) and unit cell parameters: a = 5.125(1) Å, b = 6.559(1) Å, c = 8.173(2) Å, α = 75.06(2), β = 89.25(2), γ = 69.62(2), Z = 1. Its crystal structure has been refined by a full matrix least-squares process to R₁ = 0.023 and wR₂ = 0.060 values, on the basis of 2931 independent single crystal X-ray reflections. It can be described as a three-dimensional polyhedral network of independent Te₂O₆ groups of TeO₃ trigonal pyramids and TeO₄ disphenoids sharing corners, and infinite (Te₂O₅)_∞ quasi-linear chains of the same corner-sharing TeO₃ and TeO₄ units, linked one to the other via common corner or common edge by GaO₄ and GaO₅ polyhedra. The stereochemical activity of the lone pair of each Te atom has been analysed and a comparison is made with all the known other M₂Te₄O₁₁ crystal structures.     

CoTeMoO6, Co4TeMo3O16: Two new cobalt molybdotellurates

It has been found that a solid-state reaction of CoMoO₄ with TeO₂ at 500°C yields a new compound of the formula CoTeMoO₆. This compound is also formed in the course of annealing of CoMoO₄H₆TeO₆ mixtures. Another new compound, the cobalt molybdotellurate containing Te⁶⁺, was prepared by a solid-state reaction of Co₅TeO₈ with MoO₃. It has the formula Co₄TeMo₃O₁₆. Both CoTeMoO₆ and Co₄TeMo₃O₁₆ have been characterized by X-ray method. The latter has the structure of a wolframite type with the unit cell dimensions a = 4.66, b = 5.67, c = 4.96 Å, β ? 90°.     

Solid state reactions to CdTeMoO6 and its structural characterization

CdTeMoO₆ has been obtained by solid state reactions of CdMoO₄ with orth. TeO₂ at 425°C, with tetr. TeO₂ at 470°C, and with H₆TeO₆ at 490°C. Its crystal structure belongs to the tetragonal system (space group $\text{P4}\text{n}$ or $\text{P4}\text{nmm}$ with unit cell dimensions a = 5.279(2) Å, c = 9.056(2) Å. The specificity of this compound in the allylic oxidation reactions should be strictly related to its structural features, among which the presence of cis MoO₂ groups could be very important.     

Cristallochimie de TlIII6TeVIO12 et TlI6TeVIO6E6: un exemple original de l'activite´ste´re´ochimique de la pairee´lectronique 6s2(E) du thallium(I)

Both crystal structures of Tl₆TeO₁₂ and Tl₆TeO₆E₆ compounds have been determined, the former by X-ray single crystal techniques, the latter by powder neutron diffraction techniques. They crystallize in the trigonal system, space groupR3¯ the corresponding hexagonal cell parameters area = 9.645(2) Å,c = 9.421(2) Å, anda = 9.5722(3) Å,c = 9.3494(4) Å, respectively, withZ = 3. In both compounds tellurium(VI) is octahedrally coordinated to oxygen atoms with TeO distances of 1.936Åfor the Tl(III)-containing compound, i.e., Tl₆TeO₁₂, and 1.946Åfor Tl₆TeO₆ (Tl(I)). Tl(III) is surrounded by seven oxygen atoms sitting at the summits of a distorted monocapped trigonal prism. Tl(I) is linked to three oxygen atoms, forming a distorted TlO₃ pyramid. The lone pairs brought by Tl(I) are in the positions precedingly occupied by oxygen atoms in the crystal structure of Tl₆TeO₁₂. This is an outstanding example of the crystallochemical role of the lone pairsE which act like oxygen atoms, making Tl^I₆Te^VIO₆E₆ isostructural with Tl^IIITe^VIO₁₂. Structural relationships with fluorite type network are discussed.     

Compositionally controlled metal-insulator transition in Tl2−xInxTeO6

Tl₂TeO₆ and In₂TeO₆ are both known to crystallize in the Na₂SiF₆-type structure. We find Tl₂TeO₆ is metallic, whereas In₂TeO₆ is an insulator. We have prepared a complete Tl_2−xIn_xTeO₆ series in a search for a compositionally controlled metal-insulator transition that might be expected if a complete solid solution can be obtained. Unit cell edges and volume vary monotonically with no indication of a miscibility gap. The metal-insulator transition occurs at an x value of about 1.4, which can be rationalized on a percolation model. No superconductivity could be detected down to 5 K.     

Crystal Structure of the Ordered Double Perovskite,Sr2NiTeO6

The crystal structure of the ordered double perovskite Sr₂MnTeO₆ has been refined at ambient temperature from high resolution neutron and X‐ray powder diffraction data in the monoclinic space group I 1 2/m 1 with a = 5.6166(1) Å, b = 5.5807(1) Å, c = 7.8797(1) Å and β = 90.048(2)°. The structure is the result of out‐of‐phase (–) rotations of virtually undistorted NiO₆ and TeO₆ octahedra in the (0 – –) sense about two of the axes of the ideal cubic perovskite. Electron diffraction measurements have been used to confirm the proposed space group and structure.     

Iron-57 Mössbauer spectroscopy of Cr2TeO6 and Fe2TeO6

Iron-57 Mössbauer spectroscopy has been used to determine the hyperfine field at a chromium site in Cr₂TeO₆ which is found to be 525 kOe. The Néel temperature for Cr₂TeO₆ containing 0.4% ⁵⁷Fe is found to be 90%K; the angle θ between V_zz and the magnetic axis is 42 ± 4°. These data are compared with those for Fe₂TeO₆ where H_eff (T = 0) = 530 kOe T_N = 203°K and θ = 90°.     

Etude structurale de Li2TeO4. Coordination du tellure VI et du lithium par les atomes d'oxygéne

A single crystal of Li₂TeO₄ has been prepared by hydrothermal synthesis and its structure has been determined from three-dimensional X-ray analysis. The crystals are tetragonal, space group P4₁22 with a = b = 6.045(3) Å, c = 8.290(2) Å, and Z = 4. The structure is a distorted inverse spinel with helicoidal chains of Te(VI) octahedra parallel to the [001] axis which can be formulated as [TeO₄]^2n?_n.     

Synthesis,Crystal Structure,and Properties of Mixed Salt Cs2SO4 · H6TeO6

Mixed salt Cs₂SO₄ · H₆TeO₆ (I) is synthesized and its structure and properties are studied by X-ray diffraction analysis, IR and Raman spectroscopies, impedance measurements, and differential thermal analysis. Compound I crystallizes in hexagonal system with unit cell parameters a = 7.455(1) Å, c = 33.303(7) Å, space group R3c, Z = 6. Its crystal structure consists of the H₆TeO₆ molecules and SO₄ ^2- anions united by network of hydrogen bonds and Cs⁺ cations.     

Synthese und Kristallstruktur von KTeOF3

Synthesis and Crystal Structure of KTeOF₃ KTeOF₃ has been synthesized by solid state reaction of KF, TeO₂ and KTeF₅ in equimolar amounts. Its crystal structure has been solved by single crystal structure analysis (P4₂/n, a = 1007.96(3), c = 789.58(3) pm, Z = 8, R₁ = 0.0311). As a characteristic feature, the compound contains unprecedented dimeric anions Te₂O₂F₆^2– formed by two edge‐sharing pseudo‐octahedral units. IR and Raman data are given.     

X‐Ray Crystal Structures of Hexa‐oxotellurate Complexes of Ruthenium(VI) and Silver(III): Na6[RuO2{TeO4(OH)2}2]·16H2O and Na5[Ag{TeO4(OH)2}2]·16H2O

X‐ray crystal structures are reported for Na₆[RuO₂{TeO₄(OH)₂}₂]·16H₂O and Na₅[Ag{TeO₄(OH)₂}₂]·16H₂O which contain respectively Ru^VI and Ag^III coordinated to chelating bidentate tellurate ([TeO₄(OH)₂]⁴⁻) groups. Na₆[RuO₂{TeO₄(OH)₂}₂]·16H₂O: Space group P1¯, Z = 2, lattice dimensions at 120 K; a = 6.9865(1), b = 8.7196(2), c = 11.7395(2)Å, α = 74.008(1), β = 79.954(1), γ = 88.514(1)°; R1 = 0.025. Na₅[Ag{TeO₄(OH)₂}₂]·16H₂O: Space group P1¯, Z = 2, lattice dimensions at 120 K; a = 5.888(1), b = 8.932(1), c = 12.561(2)Å, α = 98.219(6), β = 97.964(9), γ = 93.238(14)°; R1 = 0.047.     

Sc2Te5O13 und Sc2TeO6: Die ersten Oxotellurate des Scandiums

Sc₂Te₅O₁₃ and Sc₂TeO₆: The First Oxotellurates of Scandium Sc₂Te₅O₁₃ and Sc₂TeO₆ are the first oxotellurates of scandium that could be structurally elucidated by X‐ray diffraction using single crystals. The scandium(III) oxotellurate(IV) Sc₂Te₅O₁₃ was synthesized by reacting Sc₂O₃ with TeO₂ at 850 °C and crystallizes in the triclinic system with space group (no. 2) and the lattice parameters a = 660.67(5), b = 855.28(7), c = 1041.10(9) pm, α = 86.732(8), β = 86.264(8), and γ = 74.021(8)° (Z = 2). The crystal structure contains chains respectively strands of alternatingly edge‐ and vertex‐sharing [ScO₆]^9? and [ScO₇]^11? polyhedra. These strands are connected by [TeO₃₊₁]^(2+2)? oxotellurate(IV) anions. The coordination spheres of Sc³⁺ appear markedly smaller than those of M³⁺ cations in the other known compounds of the formula type M₂Te₅O₁₃ (M = Y, Dy – Lu), therefore Sc₂Te₅O₁₃ is not really isotypic, but only isopuntal with these compounds. Single crystals of the scandium(III) oxotellurate(VI) Sc₂TeO₆ were obtained through the fusion of a mixture of Sc₂O₃ and TeO₃ at 850 °C. It crystallizes trigonally (a = 874.06(7), c = 479.85(4) pm and c/a = 0.549) with the Na₂SiF₆‐type structure in space group P321 (no. 150) and three formula units per unit cell. Its crystal structure is built up by a hexagonal closest packing (hcp) of oxide anions with the Sc³⁺ cations residing in ¹/₃ and the Te⁶⁺ cations in ¹/₆ of the octahedral interstices in a well‐ordered occupation pattern. Thus one can address the structural situation in Sc₂[TeO₆] as a stuffed β‐WCl₆‐type arrangement.     

Crystal Structure of a Silver Phosphate-Tellurate: Te(OH)6 · 2Ag2HPO4

Crystal structure of a new silver phosphate-tellurate: Te(OH)₆ · 2Ag₂HPO₄ has been solved using 2534 X-ray reflections with a final R value: 0.048. This salt is monoclinic, P2₁/n with a bimolecular unit cell:a = 5.950(3), b = 20.52(1), c = 5.829(3) Å, β = 119.89(5°). As in the already described phosphate-tellurates the main feature of this crystal structures is the coexistence in the same crystal of two different types of anions: TeO₆ octahedra and PO₄ tetrahedra.     

Etude structurale d'un nouveau tellurate alcalin: Na2TeO4. Evolution de la coordination du tellure(VI) et du cation quand on passe du cation lithium au sodium

Single crystal Na₂TeO₄ has been prepared by hydrothermal synthesis and its structure determined from three dimensional X-ray analysis. The crystal is monoclinic, space group $\text{P}\text{P2}{}_1\text{c}$ with a = 10.632(5)Å, b = 5.161(2)Å; c = 13.837(11)Å, and β = 103.27(4)°. The crystal structure is built up of chains of Te(VI)O₆ octahedra parallel to the [010] axis which can be formulated as [TeO₄]_n^2n?. All sodium cations are in very distorted octahedral coordination.     

Thermodynamic investigation on M–Te–O (M = Sc, Y) system

The standard Gibbs energy of formation of M₂TeO₆ and M₆TeO₁₂ (where M = Sc, Y), was determined from its vapor pressure measurements by employing thermogravimetry-based transpiration technique. This technique was validated by measuring the vapor pressure of well-studied substances such as TeO₂(s) and CdCl₂(s). The temperature dependence of the vapor pressure of TeO₂(g) over the mixtures M₆TeO₁₂ + M₂O₃ (where M = Sc, Y), generated by the incongruent vaporization reaction, M₆TeO₁₂(s) → 3M₂O₃(s) + TeO₂(g) + ½O₂(g) were measured in the temperature range 1,413–1,473 K and 1,623–1,743 K for Sc₆TeO₁₂(s) and Y₆TeO₁₂(s), respectively. Similarly, the vapor pressure of TeO₂(g) over the mixtures M₂TeO₆(s) + M₆TeO₁₂(s) generated by the vaporization reaction, 3M₂TeO₆(s) → M₆TeO₁₂(s) + 2TeO₂(g) + O₂(g) was measured in the temperature range (1,223–1,293 K) and (1,333–1,423 K) for Sc₂TeO₆(s) and Y₂TeO₆(s), respectively. From the vapor pressure measurements, the standard Gibbs energy of formation of M₆TeO₁₂ and M₂TeO₆ were derived.     

Crystal structure of the new compound Co6(TeO3)2(TeO6)Cl2

The new compound Co₆(TeO₃)₂(TeO₆)Cl₂ has been isolated during an investigation of the system CoO:CoCl₂:TeO₂. The new compound is deep purple in color and crystallizes in the tetragonal system, space group P4₂/mbc, a=8.3871(7) Å, c=18.5634(19) Å, Z=4. The Co(II) ions have octahedral [Co1O₆] and tetrahedral [Co2O₃Cl] coordinations. Tellurium is present both as Te(IV) with a tetrahedral [Te1O₃E] coordination, where E is the 5s² lone-pair and as Te(VI) with an octahedral [Te2O₆] coordination. The structure is made up of intersecting layers of tetrahedra forming channels comprising octahedra chains that run along the c-axis. The new compound is the first cobalt tellurium oxochloride described.