inorganic compounds
Redetermination of the γ-form of tellurium dioxide
aInstitute for Chemical Technologies and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria
*Correspondence e-mail: matthias.weil@tuwien.ac.at
The γ-TeO2 was redetermined on the basis of single-crystal X-ray diffraction data. The previous of this modification was based on laboratory powder X-ray diffraction data [Champarnaud-Mesjard et al. (2000). J. Phys. Chem. Solids, 61, 1499–1507]. The current redetermination revealed all atoms with anisotropic displacement parameters, accompanied with a much higher accuracy and precision in terms of bond lengths and angles, and the determination of the The consists of TeO4 bisphenoids that combine through corner-sharing of all their oxygen atoms into a three-dimensional framework.
ofKeywords: crystal structure; redetermination; TeO2.
CCDC reference: 1589878
Structure description
In a continuation of hydrothermal phase formation studies to incorporate tetrahedral XO4 groups (X = S, Se) into framework structures of divalent metal oxotellurates(IV) (metal = Ca, Cd, Hg, Mg, Pb, Sr, Zn; Weil & Shirkhanlou, 2015, 2017a,b,c), the system Mn/Se/Te/O was investigated. In one of these experiments, single crystals of γ-TeO2 were obtained serendipitously as a minor by-product.
Tellurium dioxide is polymorphic, with three reported crystalline forms at ambient pressure: the α-form (Lindqvist, 1968), the β-form (Beyer, 1967) and the γ-form (Champarnaud-Mesjard et al., 2000). Whereas the α- and β-forms can be found in nature as the rare minerals paratellurite and tellurite, respectively, the γ-form is synthetic and can usually be obtained as a polycrystalline material by recrystallizing TeO2 glasses at low temperatures. This was also the procedure to prepare material for the previous of γ-TeO2 that was based on laboratory X-ray diffraction data and refined using the (Champarnaud-Mesjard et al., 2000). The results of the current rerefinement using modern CCD data are reported here. The previous structure model is confirmed, however, with higher accuracy and precision, as exemplified by a comparison of the bond lengths and angles (Table 1). Moreover, the of γ-TeO2 was determined (Table 2).
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In the 4 polyhedron is linked to four symmetry-related TeO4 polyhedra by sharing corners, which leads to the formation of a three-dimensional framework structure. Characteristic for the crystal chemistry of tellurium(IV) oxides or oxotellurates(IV) (Christy et al., 2016), the 5s2 electron lone pair situated at the TeIV atom is stereochemically active and points towards the open space of this arrangement (Fig. 1).
the tellurium atom is surrounded by four oxygen atoms in the shape of a bisphenoid, with a Te—O bond lengths range of 1.839 (3) – 2.241 (4) Å. Each TeOSynthesis and crystallization
100 mg TeO2, 350 mg MnSeO4·H2O and 70 mg KOH were mixed and placed in a 5 ml capacity Teflon container that was subsequently filled with 2 ml water. The container was closed with a Teflon lid and placed in a steel autoclave for ten days at 483 K under autogenous pressure. After cooling down to room temperature, the solid reaction product was filtered off and washed with water and ethanol. The obtained material consisted of a dark-brown to black powder as the main product besides few light-brown plate-like crystals and very few colourless needles. Powder X-ray diffraction of the dark-brown material revealed Mn2TeO6 (Hund, 1971), and single-crystal X-ray diffraction showed the plate-like crystals to be spiroffite-type Mn2Te3O8 (Cooper & Hawthorne, 1996); the colourless needles correspond to the title compound.
Refinement
Crystal data, data collection and structure . Coordinates and atom labels were taken from the previous (Champarnaud-Mesjard et al., 2000). The maximum and minimum electron density peaks are located 0.68 and 0.73 Å, respectively, from atom Te1.
details are summarized in Table 2Structural data
CCDC reference: 1589878
https://doi.org/10.1107/S2414314617017576/hb4189sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617017576/hb4189Isup2.hkl
Data collection: APEX2 (Bruker, 2015); cell
SAINT (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: coordinates from previous program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).O2Te | Dx = 5.837 Mg m−3 |
Mr = 159.60 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 2511 reflections |
a = 4.8809 (2) Å | θ = 4.8–32.2° |
b = 8.5668 (4) Å | µ = 15.91 mm−1 |
c = 4.3433 (2) Å | T = 296 K |
V = 181.61 (1) Å3 | Needle, colourless |
Z = 4 | 0.18 × 0.01 × 0.01 mm |
F(000) = 272 |
Bruker APEXII CCD diffractometer | 816 reflections with I > 2σ(I) |
ω–scans' | Rint = 0.056 |
Absorption correction: multi-scan (SADABS; Bruker, 2015) | θmax = 36.9°, θmin = 4.8° |
Tmin = 0.552, Tmax = 0.747 | h = −8→8 |
7370 measured reflections | k = −14→14 |
893 independent reflections | l = −7→7 |
Refinement on F2 | Primary atom site location: isomorphous structure methods |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.014P)2 + 0.0171P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.025 | (Δ/σ)max < 0.001 |
wR(F2) = 0.037 | Δρmax = 1.81 e Å−3 |
S = 1.02 | Δρmin = −1.28 e Å−3 |
893 reflections | Absolute structure: Flack x determined using 296 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
28 parameters | Absolute structure parameter: −0.03 (4) |
0 restraints |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
Te1 | 0.96976 (6) | 0.10122 (4) | 0.13698 (7) | 0.01056 (7) | |
O1 | 0.7704 (7) | 0.2822 (4) | 0.1778 (9) | 0.0147 (8) | |
O2 | 0.8602 (7) | 0.0379 (4) | 0.7347 (8) | 0.0140 (7) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Te1 | 0.01128 (12) | 0.00983 (11) | 0.01058 (11) | 0.00182 (11) | −0.00163 (11) | −0.00096 (13) |
O1 | 0.0143 (16) | 0.0114 (17) | 0.018 (2) | 0.0056 (12) | −0.0012 (14) | 0.0006 (15) |
O2 | 0.0144 (18) | 0.0200 (19) | 0.0075 (15) | −0.0067 (14) | 0.0006 (13) | −0.0036 (14) |
Te1—O1 | 1.839 (3) | O1—Te1iv | 2.241 (3) |
Te1—O2i | 1.906 (3) | O2—Te1v | 1.906 (3) |
Te1—O2ii | 2.048 (3) | O2—Te1vi | 2.048 (3) |
Te1—O1iii | 2.241 (4) | ||
O1—Te1—O2i | 100.36 (17) | O2i—Te1—O1iii | 75.60 (14) |
O1—Te1—O2ii | 93.14 (17) | O2ii—Te1—O1iii | 154.28 (13) |
O2i—Te1—O2ii | 78.68 (9) | Te1—O1—Te1iv | 131.6 (2) |
O1—Te1—O1iii | 91.69 (9) | Te1v—O2—Te1vi | 125.18 (18) |
Symmetry codes: (i) x, y, z−1; (ii) −x+3/2, −y, z−1/2; (iii) x+1/2, −y+1/2, −z; (iv) x−1/2, −y+1/2, −z; (v) x, y, z+1; (vi) −x+3/2, −y, z+1/2. |
Current refinement | Previous refinement a | |
Te1—O1 | 1.839 (3) | 1.86 (2) |
Te1—O2i | 1.906 (3) | 1.94 (2) |
Te1—O2ii | 2.048 (3) | 2.02 (2) |
Te1—O1iii | 2.241 (4) | 2.20 (2) |
O1—Te1—O2i | 100.36 (17) | 99.2 (4) |
O1—Te1—O2ii | 93.14 (17) | 91.8 (5) |
O1—Te1—O1iii | 91.69 (9) | 91.9 (5) |
O2i—Te1—O2ii | 78.68 (9) | 77.6 (5) |
O2i—Te1—O1iii | 75.60 (14) | 76.1 (4) |
O2ii—Te1—O1iii | 154.28 (13) | 153.6 (5) |
Te1—O1—Te1iv | 131.6 (2) | 133.1 (5) |
Te1v—O2—Te1vi | 125.18 (18) | 125.1 (5) |
Symmetry codes: (i) x, y, z - 1; (ii) -x + 3/2, -y, z - 1/2; (iii) x + 1/2, -y + 1/2, -z; (iv) x - 1/2, -y + 1/2, -z; (v) x, y, z + 1; (vi) -x + 3/2, -y, z + 1/2. Notes: (a) Champarnaud-Mesjard et al. (2000); lattice parameters a = 4.898 (3), b = 8.576 (4), c = 4.351 (2) Å at room temperature. |
Acknowledgements
The X-ray centre of TU Wien is acknowledged for financial support and for providing access to the single-crystal and powder X-ray diffractometers.
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