supporting information

Acta Cryst. (2013). E69, i18    [ doi:10.1107/S1600536813003875 ]

The Mg member of the isotypic series MTe6O13

M. Shirkhanlou and M. Weil

Abstract top

MgTe6O13, magnesium hexa­tellurate(IV), is isotypic with the structures of divalent first-row transition metal analogues MTe6O13 (M = Mn, Fe, Co, Ni and Zn). The asymmetric unit contains one Mg, two Te and five O atoms of which the Mg and one O atom lie on a threefold rotation axis. The structure is made up from slightly distorted [MgO6] octa­hedra (isolated from each other), distorted [TeO4] bis­phenoids and [TeO4 + 1] tetra­gonal pyramids sharing corners and edges. This arrangement leads to the formation of a dense three-dimensional structure.

Comment top

Single crystals of Mg2Te3O8 (Lin et al., 2013) and of the title compound, MgTe6O13, were obtained during hydrothermal phase formation studies in the system Mg–Se–Te–O. These two phases, along with MgTe2O5 have already been described as existing phases in the system Mg–Te–O and were characterized by their X-ray diffraction patterns at that time (Trömel & Ziethen-Reichnach, 1970). Whereas for MgTe2O5 (Weil, 2005) and Mg2Te3O8 (Lin et al., 2013) structure determinations from single-crystal data were reported, detailed structure data for MgTe6O13 were missing up to now.

MgTe6O13 is a member of the isotypic series MTe6O13 crystallizing in space group R3. Structure determinations were reported for the Co, Mn, Ni (Irvine et al., 2003), Fe (van der Lee & Astier, 2007) and Zn (Nawash et al., 2007) members. It should be mentioned that the given space group R3m for FeTe6O13 (van der Lee & Astier, 2007) is incorrect. The correct space group in fact is R3 (van der Lee, 2013). Lattice parameters and volumes of the several MTe6O13 phases are in a narrow range (Table 1), as one expects from the similar ionic radii of Mg and the first row transition metals.

The magnesium cation is located on a threefold rotation axis and is surrounded by six oxygen atoms in a slightly distored octahedral environment. Because of the high tellurium content in the structure, the [MgO6] octahedra are isolated from each other. The two distinct tellurium(IV) atoms exhibit different oxygen environments. Te1 is bonded to four oxygen atoms in form of a bisphenoid with distances ranging from 1.8524 (12) to 2.1842 (11) Å. Considering Te···O separations less than 3.1 Å, two remote O atoms (O3, O5) are also present, leading to a pentagonal pyramid [TeO4 + 2] as the resulting coordination polyhedron. Atom Te2 is bonded to four O atoms with distances ranging from 1.8489 (11) to 2.2118 (12) Å, with an additional O atom 2.5908 (12) Å away. The resulting [TeO4 + 1] polyhedron is a distorted tetragonal pyramid. It is augmented to a distorted octahedron if the remote O4 atom at a distance of 3.0387 (12) Å is also considered. For both [TeOx] polyhedra (Fig. 1, Table 2) the rules derived by Zemann for the crystal chemistry of oxotellurates(IV) are valid (Zemann, 1971).

The [MgO6], [Te1O4] and [Te2O4 + 1] building units share corners and edges, thereby forming a dense three-dimensional structure (Fig. 2). In a simpler view, the structure can be described as being built up from distorted hexagonal layers of the Mg and Te atoms extending parallel to (001) and stacked in an ABCA'B'C' sequence along [001]. The oxygen atoms are situated in the voids of this arrangement.

Related literature top

The title compound is isotypic with its Co, Mn, Ni (Irvine et al., 2003), Fe (van der Lee & Astier, 20075: van der Lee, 2013) and Zn (Nawash et al., 2007) analogues. For other phases in the system Mg–Te–O, see: Trömel & Ziethen-Reichnach (1970). For structure determinations of MgTe2O5 and Mg2Te3O8, see: Weil (2005) and Lin et al. (2013), respectively. The crystal chemistry of oxotellurates(IV) has been reviewed by Zemann (1971).

Experimental top

Magnesium oxide, tellurium dioxide and selenic acid (conc.; 96%wt) were loaded in the stoichiometric ratio 3:2:1 in a Teflon lined stainless steel autoclave (overall volume 10 ml) that was filled up to two-thirds of its volume with water. The autoclave was then heated at 503 K for one week. Few colourless single crystals of Mg2Te3O8 (Lin et al., 2013) and MgTe6O13, both with a platy habit, were isolated from the colourless solid reaction product. X-ray powder diffraction (XRPD) of the ground bulk material revealed Mg2Te3O8 and TeO2 as main products. Se-containing phases could not be identified by XRPD in the solid reaction product.

Refinement top

The atomic coordinates of isotypic ZnTe6O13 (Nawash et al., 2007) were used as starting parameters for the refinement. Reflection 003 was affected from the beamstop and was omitted from the refinement. The highest positive and negative residual electron densities are located 0.68 and 0.48 Å, respectively, from atom Te1.

Computing details top

Data collection: APEX2 (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS for Windows (Dowty, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The coordination spheres of the two tellurium(IV) atoms. Te—O bonds < 2.6 Å are given as solid lines, Te—O bonds between 2.6 and 3.1 Å as open lines; probability level of the displacement ellipsoids is 74%. [Symmetry codes: i) -y + 1, x-y+1, z; iii) -x + 2/3, -y + 1/3, -z + 1/3; iv) -x + 1, -y + 1, -z; vii) y, -x+y, -z; ix) x-y+2/3, x + 1/3, -z + 1/3.]
[Figure 2] Fig. 2. The crystal packing of the MgTe6O13 structure in a view along [100]. [MgO6] polyhedra are blue, [Te1O4] polyhedra are red and [Te2O4 + 1] polyhedra are orange. Probability level as in Fig. 1.
Magnesium hexatellurate(IV) top
Crystal data top
MgTe6O13Dx = 5.854 Mg m3
Mr = 997.91Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3Cell parameters from 9908 reflections
Hall symbol: -R 3θ = 3.2–43.5°
a = 10.1676 (2) ŵ = 15.38 mm1
c = 18.9701 (3) ÅT = 295 K
V = 1698.39 (5) Å3Plate, colourless
Z = 60.22 × 0.14 × 0.09 mm
F(000) = 2568
Data collection top
2875 independent reflections
Radiation source: fine-focus sealed tube2764 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.044
ω– and ϕ–scansθmax = 43.6°, θmin = 2.6°
Absorption correction: multi-scan
(SADABS; Bruker, 2012)
h = 1919
Tmin = 0.437, Tmax = 0.749k = 1919
50742 measured reflectionsl = 3636
Refinement top
Refinement on F2Primary atom site location: isomorphous structure methods
Least-squares matrix: full w = 1/[σ2(Fo2) + 7.6037P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.017(Δ/σ)max = 0.002
wR(F2) = 0.034Δρmax = 1.17 e Å3
S = 1.36Δρmin = 1.40 e Å3
2875 reflectionsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
62 parametersExtinction coefficient: 0.000970 (18)
0 restraints
Crystal data top
MgTe6O13Z = 6
Mr = 997.91Mo Kα radiation
Trigonal, R3µ = 15.38 mm1
a = 10.1676 (2) ÅT = 295 K
c = 18.9701 (3) Å0.22 × 0.14 × 0.09 mm
V = 1698.39 (5) Å3
Data collection top
2875 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2012)
2764 reflections with I > 2σ(I)
Tmin = 0.437, Tmax = 0.749Rint = 0.044
50742 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01762 parameters
wR(F2) = 0.0340 restraints
S = 1.36Δρmax = 1.17 e Å3
2875 reflectionsΔρmin = 1.40 e Å3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
Mg10.33330.66670.07728 (5)0.00655 (14)
Te10.237607 (11)0.082435 (11)0.095241 (5)0.00766 (2)
Te20.394752 (11)0.496265 (11)0.075896 (5)0.00633 (2)
O10.00000.00000.08633 (11)0.0085 (3)
O20.20309 (13)0.11297 (14)0.19252 (6)0.01008 (18)
O30.25075 (15)0.25178 (13)0.05181 (7)0.01187 (19)
O40.20451 (14)0.48320 (14)0.09819 (6)0.00998 (17)
O50.38463 (14)0.52546 (14)0.01971 (6)0.00969 (17)
Atomic displacement parameters (Å2) top
Mg10.0066 (2)0.0066 (2)0.0065 (3)0.00329 (11)0.0000.000
Te10.01113 (4)0.00635 (4)0.00675 (4)0.00530 (3)0.00084 (2)0.00065 (2)
Te20.00718 (4)0.00727 (4)0.00516 (3)0.00408 (3)0.00023 (2)0.00038 (2)
O10.0068 (4)0.0068 (4)0.0118 (7)0.0034 (2)0.0000.000
O20.0065 (4)0.0145 (5)0.0060 (4)0.0028 (4)0.0005 (3)0.0017 (3)
O30.0137 (5)0.0063 (4)0.0146 (5)0.0042 (4)0.0030 (4)0.0017 (3)
O40.0090 (4)0.0112 (4)0.0123 (4)0.0069 (4)0.0017 (3)0.0017 (3)
O50.0143 (5)0.0116 (4)0.0055 (4)0.0083 (4)0.0002 (3)0.0014 (3)
Geometric parameters (Å, º) top
Mg1—O5i2.0676 (12)Te1—O2vi2.1842 (11)
Mg1—O5ii2.0676 (12)Te1—O3vii2.9337 (13)
Mg1—O52.0676 (12)Te1—O5vii3.0387 (12)
Mg1—O2iii2.1596 (12)Te2—O51.8489 (11)
Mg1—O2iv2.1596 (12)Te2—O41.9186 (11)
Mg1—O2v2.1596 (12)Te2—O4i2.0286 (12)
Te1—O31.8524 (12)Te2—O32.2118 (12)
Te1—O21.9324 (11)Te2—O5viii2.5908 (12)
Te1—O12.1314 (2)Te2—O4ix3.0560 (12)
O5i—Mg1—O5ii94.67 (5)Te1x—O1—Te1xi119.377 (15)
O5i—Mg1—O594.67 (5)Te1—O2—Mg1xii130.51 (6)
O5ii—Mg1—O594.67 (5)Te1—O2—Te1vi105.30 (5)
O5i—Mg1—O2iii99.09 (5)Mg1xii—O2—Te1vi122.67 (6)
O5ii—Mg1—O2iii76.38 (5)Te1—O2—Te2vi94.79 (5)
O5—Mg1—O2iii164.10 (5)Mg1xii—O2—Te2vi84.08 (4)
O5i—Mg1—O2iv76.38 (5)Te1vi—O2—Te2vi78.72 (4)
O5ii—Mg1—O2iv164.10 (5)Te1—O2—Te1xi75.79 (4)
O5—Mg1—O2iv99.09 (5)Mg1xii—O2—Te1xi74.86 (4)
O2iii—Mg1—O2iv91.88 (5)Te1vi—O2—Te1xi140.31 (5)
O5i—Mg1—O2v164.10 (5)Te2vi—O2—Te1xi140.94 (4)
O5ii—Mg1—O2v99.09 (5)Te1—O2—Te2xiii124.64 (5)
O5—Mg1—O2v76.38 (5)Mg1xii—O2—Te2xiii77.64 (3)
O2iii—Mg1—O2v91.88 (5)Te1vi—O2—Te2xiii81.17 (4)
O2iv—Mg1—O2v91.88 (5)Te2vi—O2—Te2xiii139.31 (3)
O3—Te1—O2102.12 (6)Te1xi—O2—Te2xiii67.54 (2)
O3—Te1—O182.59 (5)Te1—O3—Te2130.72 (6)
O2—Te1—O182.98 (6)Te1—O3—Te1xiv120.60 (6)
O3—Te1—O2vi90.88 (5)Te2—O3—Te1xiv105.58 (4)
O2—Te1—O2vi74.70 (5)Te1—O3—Te1xi91.57 (5)
O1—Te1—O2vi154.89 (5)Te2—O3—Te1xi107.62 (5)
O3—Te1—O3vii81.28 (3)Te1xiv—O3—Te1xi87.42 (3)
O2—Te1—O3vii172.70 (4)Te2—O4—Te2ii136.27 (7)
O1—Te1—O3vii91.12 (6)Te2—O4—Te2xiii106.42 (5)
O2vi—Te1—O3vii111.91 (4)Te2ii—O4—Te2xiii103.43 (4)
O3—Te1—O5vii89.65 (5)Te2—O4—Te1xi115.96 (5)
O2—Te1—O5vii130.80 (4)Te2ii—O4—Te1xi98.97 (4)
O1—Te1—O5vii146.21 (6)Te2xiii—O4—Te1xi82.34 (3)
O2vi—Te1—O5vii57.32 (4)Te2—O4—Te2i71.27 (4)
O3vii—Te1—O5vii55.14 (3)Te2ii—O4—Te2i70.62 (3)
O5—Te2—O495.29 (5)Te2xiii—O4—Te2i104.98 (3)
O5—Te2—O4i94.31 (5)Te1xi—O4—Te2i168.27 (4)
O4—Te2—O4i93.39 (7)Te2—O5—Mg1133.10 (7)
O5—Te2—O385.36 (5)Te2—O5—Te2viii105.65 (5)
O4—Te2—O383.67 (5)Mg1—O5—Te2viii111.82 (5)
O4i—Te2—O3177.00 (5)Te2—O5—Te1xiv112.67 (5)
O5—Te2—O5viii74.35 (5)Mg1—O5—Te1xiv94.65 (4)
O4—Te2—O5viii166.09 (5)Te2viii—O5—Te1xiv90.25 (3)
O4i—Te2—O5viii96.57 (5)Te2—O5—Te2i71.20 (4)
O3—Te2—O5viii86.22 (5)Mg1—O5—Te2i68.01 (4)
O5—Te2—O4ix160.15 (4)Te2viii—O5—Te2i114.99 (4)
O4—Te2—O4ix72.54 (5)Te1xiv—O5—Te2i153.01 (4)
O4i—Te2—O4ix71.41 (4)Te2—O5—Te2ii71.12 (4)
O3—Te2—O4ix108.16 (4)Mg1—O5—Te2ii67.95 (4)
O5viii—Te2—O4ix119.92 (3)Te2viii—O5—Te2ii172.20 (5)
Te1—O1—Te1x119.377 (15)Te1xiv—O5—Te2ii97.55 (3)
Te1—O1—Te1xi119.377 (15)Te2i—O5—Te2ii57.381 (17)
Symmetry codes: (i) y+1, xy+1, z; (ii) x+y, x+1, z; (iii) y+1/3, xy+2/3, z1/3; (iv) x+1/3, y+2/3, z1/3; (v) x+y+1/3, x+2/3, z1/3; (vi) x+2/3, y+1/3, z+1/3; (vii) y, x+y, z; (viii) x+1, y+1, z; (ix) xy+2/3, x+1/3, z+1/3; (x) x+y, x, z; (xi) y, xy, z; (xii) x1/3, y2/3, z+1/3; (xiii) y1/3, x+y+1/3, z+1/3; (xiv) xy, x, z.

Experimental details

Crystal data
Chemical formulaMgTe6O13
Crystal system, space groupTrigonal, R3
Temperature (K)295
a, c (Å)10.1676 (2), 18.9701 (3)
V3)1698.39 (5)
Radiation typeMo Kα
µ (mm1)15.38
Crystal size (mm)0.22 × 0.14 × 0.09
Data collection
DiffractometerBruker APEXII CCD
Absorption correctionMulti-scan
(SADABS; Bruker, 2012)
Tmin, Tmax0.437, 0.749
No. of measured, independent and
observed [I > 2σ(I)] reflections
50742, 2875, 2764
(sin θ/λ)max1)0.970
R[F2 > 2σ(F2)], wR(F2), S 0.017, 0.034, 1.36
No. of reflections2875
No. of parameters62
Δρmax, Δρmin (e Å3)1.17, 1.40

Computer programs: APEX2 (Bruker, 2012), SAINT (Bruker, 2012), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ATOMS for Windows (Dowty, 2008), publCIF (Westrip, 2010).

Selected bond lengths (Å) top
Mg1—O52.0676 (12)Te2—O51.8489 (11)
Mg1—O2i2.1596 (12)Te2—O41.9186 (11)
Te1—O31.8524 (12)Te2—O4iii2.0286 (12)
Te1—O21.9324 (11)Te2—O32.2118 (12)
Te1—O12.1314 (2)Te2—O5iv2.5908 (12)
Te1—O2ii2.1842 (11)
Symmetry codes: (i) y+1/3, xy+2/3, z1/3; (ii) x+2/3, y+1/3, z+1/3; (iii) y+1, xy+1, z; (iv) x+1, y+1, z.
Structural data of isotypic MTe6O13 compounds (Å, Å3) in space group R3 top
Mga10.1676 (2)18.9701 (3)1698.39 (5)
Mnb10.2505 (5)19.2195 (9)1748.89 (14)
Fec10.16630 (10)18.9330 (3)1694.63 (4)
Cob10.1641 (5)18.9814 (9)1698.23 (14)
Nib10.1522 (5)18.8669 (9)1684.30 (14)
Znd10.1283 (9)18.948 (3)1683.3 (3)
Notes: (a) this work; (b) Irvine et al. (2003); (c) van der Lee & Astier (2007); (d) Nawash et al. (2007).
Acknowledgements top

The X-ray centre of the Vienna University of Technology is acknowledged for financial support and for providing access to the single-crystal diffractometer.