Acta Cryst. (2007). E63, i146-i147 [ doi:10.1107/S1600536807024014 ]
Single crystals of the cobalt magnesium dichloride tetrakis[trioxotellurate(IV)] solid solution Co5-yMgy(TeO3)4Cl2 [y = 1.4] were obtained from solid-gas phase reactions in sealed evacuated silica tubes. The crystal symmetry is monoclinic and the compound is isostructural with Co5(TeO3)4X2 and Ni5(TeO3)4X2 (X = Cl, Br). The layered structure comprises distorted MO6 and MO5Cl octahedra (M = statistically occupied Co and Mg sites) and TeO3E tetrahedra (E = stereochemically active electron lone pair of TeIV). Five face-sharing MO6 octahedra make up claw-like [M5O16Cl2] units which form layers by corner-sharing with four other such units and by corner- and edge-sharing with TeO3E tetrahedra. The layers are held together only by weak van der Waals forces with a closest Te
Cl distance of 3.184 (2) Å between two layers.
Single crystals of compound (I) were synthesized from MgO (Merck, 99.99%), CoCl2 (Aldrich, +97%), CoO (Alfa Aesar, +99%), and TeO2 (ABCR, +99%) in the molar ratio 1:1:1:2. The components were mixed in a mortar and placed in a silica tube (length ~5 cm) which was then evacuated. The sample tube was heated at 920 K for 70 h in a muffle furnace to allow for solid-gas phase reactions. The final non-hygroscopic product consisted of a mixture of a purple powder, a brown powder, and blue transparent prismatic single crystals of (I). Analysis by energy dispersive spectrometry (EDS, LINK AN10000) of the crystal used for the diffraction experiment gave (at-%): 36.3% Te, 33.0% Co, 12.5% Mg, and 18.1% Cl. The Co:Mg ratio was thus found to be 73:27 = 2.7 which is in very good agreement with the composition determined from structure refinement (ratio 2.6).
The initial refinement presumed a structure without incorporation of magnesium and converged with good residuals, but the occupancy and the displacement parameters for the Co positions proved unsatisfactory. Refinement by assuming fully occupied metal sites and allowing for a statistical occupation of Co and Mg showed that the M(1) site is occupied by Mg with approximately 50%, the M(2) site with 13%, and the M(3) site with 32%. The highest peak and the deepest hole in the residual electron density map are 0.89 Å and 0.71 Å, respectively, from Te(1) and Te(2).
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: JANA2000 (Petříček et al., 2000); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: JANA2000.
| Co3.617Mg1.383Cl2(TeO3)4 | F(000) = 1809 |
| Mr = 1020.08 | Dx = 4.832 Mg m−3 |
| Monoclinic, C2/c | Mo Kα radiation, λ = 0.71069 Å |
| Hall symbol: -C 2yc | Cell parameters from 5897 reflections |
| a = 19.8551 (11) Å | θ = 3.9–36.8° |
| b = 5.2584 (2) Å | µ = 12.87 mm−1 |
| c = 16.4637 (10) Å | T = 292 K |
| β = 125.3607 (7)° | Prism, blue |
| V = 1401.81 (13) Å3 | 0.11 × 0.10 × 0.08 mm |
| Z = 4 |
| Oxford Diffraction Xcalibur3 diffractometer | 3246 independent reflections |
| Radiation source: fine-focus sealed tube | 2376 reflections with I > 3σ(I) |
| graphite | Rint = 0.056 |
| Detector resolution: 6.7 pixels mm-1 | θmax = 36.8°, θmin = 4.1° |
| φ–scan | h = −33→33 |
| Absorption correction: numerical [X-RED (Stoe & Cie, 1999) and X-SHAPE (Stoe & Cie, 2001)] | k = −6→8 |
| Tmin = 0.145, Tmax = 0.220 | l = −23→27 |
| 8065 measured reflections |
| Refinement on F | 108 parameters |
| R[F2 > 2σ(F2)] = 0.044 | Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0004F2) |
| wR(F2) = 0.064 | (Δ/σ)max = 0.018 |
| S = 1.48 | Δρmax = 3.82 e Å−3 |
| 3246 reflections | Δρmin = −3.94 e Å−3 |
| Co3.617Mg1.383Cl2(TeO3)4 | V = 1401.81 (13) Å3 |
| Mr = 1020.08 | Z = 4 |
| Monoclinic, C2/c | Mo Kα radiation |
| a = 19.8551 (11) Å | µ = 12.87 mm−1 |
| b = 5.2584 (2) Å | T = 292 K |
| c = 16.4637 (10) Å | 0.11 × 0.10 × 0.08 mm |
| β = 125.3607 (7)° |
| Oxford Diffraction Xcalibur3 diffractometer | 3246 independent reflections |
| Absorption correction: numerical [X-RED (Stoe & Cie, 1999) and X-SHAPE (Stoe & Cie, 2001)] | 2376 reflections with I > 3σ(I) |
| Tmin = 0.145, Tmax = 0.220 | Rint = 0.056 |
| 8065 measured reflections | θmax = 36.8° |
| R[F2 > 2σ(F2)] = 0.044 | Δρmax = 3.82 e Å−3 |
| wR(F2) = 0.064 | Δρmin = −3.94 e Å−3 |
| S = 1.48 | Absolute structure: ? |
| 3246 reflections | Flack parameter: ? |
| 108 parameters | Rogers parameter: ? |
| ? restraints |
Refinement. Single crystal X-ray data was collected on an Oxford Diffraction Xcalibur3 diffractometer using graphite-monochromated Mo Kα radiation, λ = 0.71073 Å. The intensities of the reflections were integrated using the supplied software CrysAlis (Oxford Diffraction, 2006) by the manufacturer. Numerical absorption correction was performed with the programs X-RED (Stoe & Cie, 1999) and X-SHAPE (Stoe & Cie, 2001). The structure was solved by direct methods: SHELXS97 (Sheldrick, 1997) and refined by full matrix least squares on F using the program JANA2000 (Petříček et al., 2000). All atoms including the mixed Co and Mg positions were refined with anisotropic temperature parameters. Molecular graphics were prepared with the program DIAMOND (Brandenburg, 1996). |
| x | y | z | Uiso*/Ueq | Occ. (<1) | |
| Te1 | 0.37266 (2) | 0.19170 (7) | 0.36070 (2) | 0.01174 (14) | |
| Te2 | 0.14654 (2) | 0.28795 (7) | 0.37921 (2) | 0.01156 (13) | |
| Co1 | 0 | −0.2441 (3) | 0.25 | 0.0193 (7) | 0.500 (10) |
| Mg1 | 0 | −0.244 (3) | 0.25 | 0.0193 (7) | 0.500 (10) |
| Co2 | 0.09308 (5) | −0.22203 (15) | 0.47692 (6) | 0.0126 (3) | 0.874 (7) |
| Mg2 | 0.09308 (5) | −0.22203 (15) | 0.47692 (6) | 0.0126 (3) | 0.126 (7) |
| Co3 | −0.01002 (6) | 0.22050 (18) | 0.38052 (6) | 0.0129 (4) | 0.685 (8) |
| Mg3 | −0.01002 (6) | 0.22050 (18) | 0.38052 (6) | 0.0129 (4) | 0.315 (8) |
| Cl1 | 0.25953 (10) | −0.1767 (3) | 0.40309 (12) | 0.0252 (6) | |
| O1 | 0.0661 (2) | 0.5050 (7) | 0.3715 (3) | 0.0140 (14) | |
| O2 | 0.1135 (3) | 0.3485 (8) | 0.2513 (3) | 0.0199 (17) | |
| O3 | −0.0733 (2) | 0.3903 (7) | 0.4283 (3) | 0.0144 (15) | |
| O4 | 0.0777 (2) | 0.0109 (7) | 0.3549 (3) | 0.0144 (15) | |
| O5 | −0.0432 (2) | −0.1600 (7) | 0.3564 (3) | 0.0142 (15) | |
| O6 | 0.0971 (2) | 0.1415 (8) | 0.5224 (3) | 0.0169 (16) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Te1 | 0.01354 (16) | 0.01096 (16) | 0.01182 (15) | 0.00027 (11) | 0.00798 (12) | 0.00053 (10) |
| Te2 | 0.01231 (15) | 0.01128 (16) | 0.01157 (14) | 0.00008 (11) | 0.00718 (12) | −0.00018 (10) |
| Co1 | 0.0244 (9) | 0.0110 (7) | 0.0117 (7) | 0 | 0.0041 (6) | 0 |
| Mg1 | 0.0244 (9) | 0.0110 (7) | 0.0117 (7) | 0 | 0.0041 (6) | 0 |
| Co2 | 0.0178 (4) | 0.0093 (4) | 0.0134 (4) | 0.0010 (3) | 0.0107 (3) | 0.0004 (3) |
| Mg2 | 0.0178 (4) | 0.0093 (4) | 0.0134 (4) | 0.0010 (3) | 0.0107 (3) | 0.0004 (3) |
| Co3 | 0.0161 (5) | 0.0106 (5) | 0.0149 (4) | 0.0008 (3) | 0.0107 (4) | 0.0006 (3) |
| Mg3 | 0.0161 (5) | 0.0106 (5) | 0.0149 (4) | 0.0008 (3) | 0.0107 (4) | 0.0006 (3) |
| Cl1 | 0.0197 (6) | 0.0307 (8) | 0.0244 (7) | 0.0018 (6) | 0.0122 (5) | −0.0025 (6) |
| O1 | 0.0169 (17) | 0.0094 (16) | 0.0149 (15) | 0.0027 (14) | 0.0088 (13) | 0.0015 (13) |
| O2 | 0.025 (2) | 0.0213 (19) | 0.0144 (16) | −0.0048 (17) | 0.0123 (15) | 0.0025 (15) |
| O3 | 0.0213 (18) | 0.0119 (16) | 0.0154 (15) | 0.0028 (15) | 0.0136 (14) | 0.0039 (13) |
| O4 | 0.0169 (17) | 0.0123 (16) | 0.0173 (16) | −0.0040 (14) | 0.0118 (14) | −0.0029 (13) |
| O5 | 0.0154 (17) | 0.0096 (16) | 0.0200 (17) | −0.0001 (14) | 0.0116 (14) | 0.0015 (13) |
| O6 | 0.0240 (19) | 0.0121 (16) | 0.0156 (16) | 0.0012 (16) | 0.0120 (15) | −0.0002 (14) |
| Te1—O2i | 2.706 (5) | M2—Mg3 | 2.8920 (7) |
| Te1—O3ii | 1.876 (4) | M2—Cl1viii | 2.4616 (16) |
| Te1—O5iii | 1.881 (5) | M2—O1v | 2.069 (4) |
| Te1—O6iv | 1.870 (4) | M2—O3ix | 2.020 (5) |
| Te2—O1 | 1.907 (5) | M2—O4 | 2.218 (5) |
| Te2—O2 | 1.834 (5) | M2—O5 | 2.270 (3) |
| Te2—O4 | 1.876 (4) | M2—O6 | 2.037 (4) |
| M1—O1v | 2.104 (4) | M3—O1 | 2.191 (5) |
| M1—O1vi | 2.104 (4) | M3—O2vii | 2.056 (3) |
| M1—O4 | 2.019 (3) | M3—O3 | 2.035 (5) |
| M1—O4vii | 2.019 (3) | M3—O4 | 2.296 (5) |
| M1—O5 | 2.397 (6) | M3—O5 | 2.072 (4) |
| M1—O5vii | 2.397 (6) | M3—O6 | 2.098 (3) |
| M2—M3 | 2.8920 (12) | ||
| O2i—Te1—O3ii | 65.95 (16) | Cl1viii—M2—O4 | 108.86 (13) |
| O2i—Te1—O5iii | 78.97 (17) | Cl1viii—M2—O5 | 174.24 (13) |
| O2i—Te1—O6iv | 156.31 (14) | Cl1viii—M2—O6 | 97.62 (11) |
| O3ii—Te1—O5iii | 99.06 (19) | O1v—M2—O3ix | 105.78 (17) |
| O3ii—Te1—O6iv | 93.00 (17) | O1v—M2—O4 | 77.91 (16) |
| O5iii—Te1—O6iv | 94.6 (2) | O1v—M2—O5 | 76.57 (16) |
| O1—Te2—O2 | 95.2 (2) | O1v—M2—O6 | 153.49 (16) |
| O1—Te2—O4 | 88.37 (19) | O3ix—M2—O4 | 162.76 (17) |
| O2—Te2—O4 | 99.07 (18) | O3ix—M2—O5 | 94.10 (17) |
| O1v—M1—O1vi | 102.34 (15) | O3ix—M2—O6 | 96.4 (2) |
| O1v—M1—O4 | 81.71 (14) | O4—M2—O5 | 70.09 (17) |
| O1v—M1—O4vii | 167.7 (2) | O4—M2—O6 | 76.70 (17) |
| O1v—M1—O5 | 73.18 (17) | O5—M2—O6 | 87.68 (14) |
| O1v—M1—O5vii | 121.38 (17) | O1—M3—O2vii | 90.70 (17) |
| O1vi—M1—O1v | 102.34 (15) | O1—M3—O3 | 109.33 (18) |
| O1vi—M1—O4 | 167.7 (2) | O1—M3—O4 | 71.91 (16) |
| O1vi—M1—O4vii | 81.71 (14) | O1—M3—O5 | 143.3 (2) |
| O1vi—M1—O5 | 121.38 (17) | O1—M3—O6 | 85.17 (16) |
| O1vi—M1—O5vii | 73.18 (17) | O2vii—M3—O3 | 78.53 (19) |
| O4—M1—O4vii | 96.75 (15) | O2vii—M3—O4 | 111.34 (19) |
| O4—M1—O5 | 70.82 (18) | O2vii—M3—O5 | 95.80 (15) |
| O4—M1—O5vii | 94.78 (18) | O2vii—M3—O6 | 172.04 (17) |
| O4vii—M1—O4 | 96.75 (15) | O3—M3—O4 | 170.13 (13) |
| O4vii—M1—O5 | 94.78 (18) | O3—M3—O5 | 107.4 (2) |
| O4vii—M1—O5vii | 70.82 (18) | O3—M3—O6 | 96.41 (18) |
| O5—M1—O5vii | 158.73 (15) | O4—M3—O5 | 72.10 (18) |
| O5vii—M1—O5 | 158.73 (15) | O4—M3—O6 | 73.83 (17) |
| Cl1viii—M2—O1v | 97.67 (12) | O5—M3—O6 | 91.56 (14) |
| Cl1viii—M2—O3ix | 87.56 (12) |
| Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2; (ii) x+1/2, y−1/2, z; (iii) x+1/2, y+1/2, z; (iv) −x+1/2, −y+1/2, −z+1; (v) x, y−1, z; (vi) −x, y−1, −z+1/2; (vii) −x, y, −z+1/2; (viii) −x+1/2, −y−1/2, −z+1; (ix) −x, −y, −z+1. |
| Te1—O3i | 1.876 (4) | M2—Cl1vii | 2.4616 (16) |
| Te1—O5ii | 1.881 (5) | M2—O1iv | 2.069 (4) |
| Te1—O6iii | 1.870 (4) | M2—O3viii | 2.020 (5) |
| Te2—O1 | 1.907 (5) | M2—O4 | 2.218 (5) |
| Te2—O2 | 1.834 (5) | M2—O5 | 2.270 (3) |
| Te2—O4 | 1.876 (4) | M2—O6 | 2.037 (4) |
| M1—O1iv | 2.104 (4) | M3—O1 | 2.191 (5) |
| M1—O1v | 2.104 (4) | M3—O2vi | 2.056 (3) |
| M1—O4 | 2.019 (3) | M3—O3 | 2.035 (5) |
| M1—O4vi | 2.019 (3) | M3—O4 | 2.296 (5) |
| M1—O5 | 2.397 (6) | M3—O5 | 2.072 (4) |
| M1—O5vi | 2.397 (6) | M3—O6 | 2.098 (3) |
| Symmetry codes: (i) x+1/2, y−1/2, z; (ii) x+1/2, y+1/2, z; (iii) −x+1/2, −y+1/2, −z+1; (iv) x, y−1, z; (v) −x, y−1, −z+1/2; (vi) −x, y, −z+1/2; (vii) −x+1/2, −y−1/2, −z+1; (viii) −x, −y, −z+1. |
This work has been carried out through financial support from the Swedish research council.
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![[Figure 1]](./wm2109fig1thm.gif)
The aim of this study was to introduce MgII into the CoII—TeIV—O—Cl system. Some few transition metal oxohalides comprising both TeIV and an alkaline earth element have been described before, e.g. Ba2Cu4Te4O11Cl4 (Feger & Kolis, 1998), Ca2CuTe4O10Cl2 (Takagi & Johnsson, 2005), Sr2Cu2TeO6Br2 (Takagi & Johnsson, 2006) and SrCu2(TeO3)2Cl2 (Takagi et al., 2006). In this communication we report the synthesis and crystal structure of the new compound Co3.6Mg1.4(TeO3)4Cl2 (I). The refinement proved (I) to be isostructural to Co5(TeO3)4X2 (X = Cl, Br) (Becker, Prester, Berger, Johnsson et al., 2007) and Ni5(TeO3)4X2 (Johnsson et al., 2003). The corresponding Se-compounds are, however, not isostructural and the four compounds Co5(SeO3)4X2 and Ni5(SeO3)4X2 (X=Cl, Br) are all triclinic and crystallize in two different structure types (Becker, Prester, Berger, Hui Lin et al., 2007; Jiang & Mao, 2006; Shen et al., 2005).
There are two crystallographic distinct Te positions that both have a TeO3E tetrahedral coordination (E = lone pair electrons of TeIV). The Te(1)O3E tetrahedron is quite regular while the Te(2)O3E tetrahedron is more distorted. Te(1) has a fourth neighbouring oxygen atom located at 2.706 (5) Å, however, a distance that is too long to be considered as belonging to the primary coordination sphere. Geometrically placing the lone pairs under assumption of a Te - E distance (radius) of 1.25 Å (Galy et al., 1975) gives the fractional coordinates for E(1) with x = 0.3149, y = 0.1870, z = 0.2989, and for E(2) with x = 0.2073, y = 0.2878, z = 0.4325, respectively. The metal positions, M, are statistically occupied by Co and Mg. The M(1) and M(3) sites have a distorted MO6 octahedral coordination with M—O distances ranging from 2.019 (3) Å to 2.397 (6) Å). The M(2) site has a MO5Cl distorted octahedral coordination with M—O distances ranging from 2.020 (5) to 2.270 (3) Å, while the M—Cl distance is 2.4616 (16) Å (Table 1).
The structural arrangement of (I) is layered, see Figure 1. The layers extend parallel to (100) and consist of TeO3E, MO6 and MO5Cl polyhedra. The M-polyhedra make up building blocks constituting five MO6 octahedra which, by face sharing, make up a claw-like [M5O16Cl2] unit. These units form layers by corner-sharing to four other such units and by corner- and edge-sharing to the TeO3E tetrahedra. The halides and the electron lone-pairs (E) of TeIV protrude from the layers to the empty space. The closest Te—Cl distance between two layers is 3.184 (2) Å. This distance is substantially shorter than the expected van der Waals distance of 3.81 Å (Bondi, 1964) indicating that there is a stronger interaction between two layers.
The highest fraction of Mg is present at the M(1) and M(3) sites that both coordinate solely to oxygen atoms. The shortest M—M distance between two layers is 5.832 (2) Å, which is slightly longer than in the structure of Co5(TeO3)4Cl2 (5.690 (7) Å).