Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270105028210/sq1228sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270105028210/sq1228Isup2.hkl |
Stoichiometric amounts of AgNO3 (Fluka, p·A.), Hg2(NO3)2·2H2O (Merck, p·A.) and H6TeO6 (Aldrich, 99%) were mixed in the molar ratio 6:2:1 and put into a Teflon inlay with 10 ml capacity. The inlay was filled to two-thirds with demineralized water, sealed and placed in a steel autoclave, which was heated at 523 K for three weeks. After the reaction time, a few red single crystals of Ag2Hg2(TeO4)3 (approximate yield 2%) with a needle-like habit were obtained. Besides the main phase consisting of dark-red crystals of Ag2TeO4 (Klein et al., 2005), minor amounts (ca 5% yield) of colourless crystals of a yet unknown composition were also present in the reaction mixture. Multiphase formation of crystalline products has been observed for several systems Ag–Hg–X–O (X = P, As, Se and V; Weil, 2003; Weil et al. 2005). This behavior is caused by complex interplays of different redox, protolysis and precipitation equilibria taking place under hydrothermal conditions.
Refinement of the occupation factors for the individual metal atoms did not reveal any statistical disorder of Ag and Hg over the two metal sites. The highest peak in the final Fourier map is located 0.84 Å from Hg and the deepest hole 0.55 Å from Ag.
Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 2004); software used to prepare material for publication: SHELXL97.
Ag2Hg2(TeO4)3 | F(000) = 1012 |
Mr = 1191.72 | Dx = 7.614 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 2690 reflections |
a = 6.4664 (6) Å | θ = 3.1–30.5° |
b = 6.1623 (5) Å | µ = 41.48 mm−1 |
c = 13.0851 (11) Å | T = 295 K |
β = 94.548 (2)° | Needle, red |
V = 519.77 (8) Å3 | 0.15 × 0.03 × 0.02 mm |
Z = 2 |
Bruker SMART APEX CCD diffractometer | 1573 independent reflections |
Radiation source: fine-focus sealed tube | 1366 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.044 |
ω scans | θmax = 30.5°, θmin = 3.1° |
Absorption correction: numerical (HABITUS; Herrendorf, 1997) | h = −9→9 |
Tmin = 0.078, Tmax = 0.683 | k = −8→8 |
5772 measured reflections | l = −18→18 |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.024 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.052 | w = 1/[σ2(Fo2) + (0.0208P)2 + 0.7394P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
1573 reflections | Δρmax = 1.97 e Å−3 |
88 parameters | Δρmin = −1.44 e Å−3 |
Ag2Hg2(TeO4)3 | V = 519.77 (8) Å3 |
Mr = 1191.72 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.4664 (6) Å | µ = 41.48 mm−1 |
b = 6.1623 (5) Å | T = 295 K |
c = 13.0851 (11) Å | 0.15 × 0.03 × 0.02 mm |
β = 94.548 (2)° |
Bruker SMART APEX CCD diffractometer | 1573 independent reflections |
Absorption correction: numerical (HABITUS; Herrendorf, 1997) | 1366 reflections with I > 2σ(I) |
Tmin = 0.078, Tmax = 0.683 | Rint = 0.044 |
5772 measured reflections |
R[F2 > 2σ(F2)] = 0.024 | 88 parameters |
wR(F2) = 0.052 | 0 restraints |
S = 1.03 | Δρmax = 1.97 e Å−3 |
1573 reflections | Δρmin = −1.44 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | ||
Hg | 0.30593 (4) | 0.45775 (5) | 0.59921 (2) | 0.01283 (7) | |
Te1 | 0.5000 | 1.0000 | 0.5000 | 0.00739 (12) | |
Te2 | 0.01778 (6) | 0.90610 (7) | 0.60759 (3) | 0.00733 (9) | |
Ag | 0.68372 (9) | 0.86909 (10) | 0.79023 (5) | 0.02104 (14) | |
O1 | 0.0017 (7) | 1.0316 (8) | 0.7343 (3) | 0.0112 (9) | |
O2 | 0.7139 (7) | 0.8722 (8) | 0.5941 (4) | 0.0090 (9) | |
O3 | 0.0116 (7) | 0.8125 (8) | 0.4626 (3) | 0.0098 (9) | |
O4 | 0.5569 (7) | 1.2823 (8) | 0.5555 (4) | 0.0135 (10) | |
O5 | 0.3191 (7) | 0.9398 (8) | 0.6091 (3) | 0.0111 (9) | |
O6 | 0.0506 (8) | 0.6147 (8) | 0.6481 (4) | 0.0149 (11) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Hg | 0.01085 (12) | 0.01191 (13) | 0.01595 (13) | 0.00265 (10) | 0.00236 (9) | −0.00216 (10) |
Te1 | 0.0057 (2) | 0.0077 (3) | 0.0089 (3) | 0.0002 (2) | 0.0017 (2) | −0.0002 (2) |
Te2 | 0.00623 (18) | 0.0082 (2) | 0.00771 (19) | 0.00059 (14) | 0.00166 (14) | 0.00049 (14) |
Ag | 0.0206 (3) | 0.0204 (3) | 0.0236 (3) | −0.0023 (2) | 0.0113 (2) | −0.0011 (2) |
O1 | 0.010 (2) | 0.017 (3) | 0.006 (2) | 0.0006 (19) | 0.0003 (17) | 0.0011 (19) |
O2 | 0.003 (2) | 0.011 (2) | 0.012 (2) | −0.0006 (17) | −0.0014 (17) | 0.0064 (18) |
O3 | 0.017 (2) | 0.006 (2) | 0.007 (2) | 0.0012 (18) | −0.0004 (18) | −0.0021 (17) |
O4 | 0.008 (2) | 0.011 (2) | 0.021 (3) | 0.0003 (18) | −0.0018 (19) | −0.004 (2) |
O5 | 0.007 (2) | 0.017 (3) | 0.010 (2) | −0.0032 (19) | 0.0023 (17) | 0.0010 (19) |
O6 | 0.017 (2) | 0.010 (2) | 0.019 (3) | 0.0044 (19) | 0.007 (2) | 0.006 (2) |
Hg—O6 | 2.059 (5) | Ag—O6ix | 2.330 (5) |
Hg—O4i | 2.068 (5) | Ag—O1ii | 2.410 (5) |
Hg—O1ii | 2.464 (4) | Ag—O1x | 2.450 (5) |
Hg—O3iii | 2.717 (5) | Ag—O4xi | 2.576 (5) |
Hg—O4iv | 2.782 (5) | Ag—O2 | 2.589 (5) |
Hg—O5 | 2.975 (5) | Ag—O3xii | 2.824 (5) |
Hg—O5i | 3.195 (5) | Ag—O5 | 3.237 (5) |
Hg—O2v | 3.240 (5) | Ag—Te2x | 3.3538 (7) |
Te1—O4iv | 1.910 (5) | O1—Agix | 2.410 (5) |
Te1—O4 | 1.910 (5) | O1—Agviii | 2.450 (5) |
Te1—O2iv | 1.945 (4) | O1—Hgix | 2.464 (4) |
Te1—O2 | 1.945 (4) | O1—Hgvi | 3.801 (5) |
Te1—O5iv | 1.952 (5) | O1—Agii | 4.260 (5) |
Te1—O5 | 1.952 (5) | O2—Te2x | 1.970 (4) |
Te1—Hgv | 3.3875 (3) | O2—Hgv | 3.240 (5) |
Te1—Hgvi | 3.3875 (3) | O2—Agxiii | 3.456 (5) |
Te1—Hgiv | 3.8320 (4) | O2—Agxi | 3.490 (5) |
Te1—Agiv | 3.9710 (7) | O3—Te2vii | 1.964 (5) |
Te1—Ag | 3.9710 (7) | O3—Hgiii | 2.717 (5) |
Te2—O1 | 1.840 (5) | O3—Agxiv | 2.824 (5) |
Te2—O6 | 1.880 (5) | O4—Hgvi | 2.068 (5) |
Te2—O5 | 1.958 (4) | O4—Agxiii | 2.576 (5) |
Te2—O3vii | 1.964 (5) | O4—Hgiv | 2.782 (5) |
Te2—O2viii | 1.970 (4) | O5—Hgvi | 3.195 (5) |
Te2—O3 | 1.981 (4) | O5—Hgix | 3.965 (5) |
Te2—Te2vii | 3.0360 (9) | O5—Agxiii | 4.289 (5) |
Te2—Agviii | 3.3538 (7) | O6—Agii | 2.330 (5) |
Te2—Agix | 3.4499 (8) | O6—Agviii | 3.499 (5) |
Te2—Agii | 3.8357 (8) | O6—Hgiii | 3.848 (5) |
Te2—Hgvi | 3.8823 (6) | O6—Hgix | 3.971 (5) |
O6—Hg—O4i | 176.2 (2) | Agix—O1—Hgvi | 67.17 (11) |
O6—Hg—O1ii | 89.97 (18) | Agviii—O1—Hgvi | 154.00 (18) |
O4i—Hg—O1ii | 89.35 (17) | Hgix—O1—Hgvi | 107.17 (14) |
O6—Hg—O3iii | 76.98 (18) | Te2—O1—Agii | 64.22 (14) |
O4i—Hg—O3iii | 100.86 (16) | Agix—O1—Agii | 133.09 (15) |
O1ii—Hg—O3iii | 133.86 (15) | Agviii—O1—Agii | 52.64 (10) |
O6—Hg—O4iv | 105.41 (16) | Hgix—O1—Agii | 90.52 (14) |
O4i—Hg—O4iv | 78.30 (19) | Hgvi—O1—Agii | 141.28 (13) |
O1ii—Hg—O4iv | 111.69 (15) | Te1—O2—Te2x | 131.9 (2) |
O3iii—Hg—O4iv | 114.43 (14) | Te1—O2—Ag | 121.7 (2) |
O6—Hg—O5 | 62.49 (16) | Te2x—O2—Ag | 93.74 (17) |
O4i—Hg—O5 | 120.92 (16) | Te1—O2—Hgv | 77.14 (15) |
O1ii—Hg—O5 | 76.49 (15) | Te2x—O2—Hgv | 96.55 (17) |
O3iii—Hg—O5 | 130.06 (13) | Ag—O2—Hgv | 140.16 (17) |
O4iv—Hg—O5 | 56.43 (14) | Te1—O2—Agxiii | 91.16 (16) |
O6—Hg—O5i | 118.43 (16) | Te2x—O2—Agxiii | 73.25 (14) |
O4i—Hg—O5i | 58.00 (16) | Ag—O2—Agxiii | 66.38 (11) |
O1ii—Hg—O5i | 97.96 (14) | Hgv—O2—Agxiii | 153.14 (15) |
O3iii—Hg—O5i | 54.33 (13) | Te1—O2—Agxi | 137.3 (2) |
O4iv—Hg—O5i | 126.57 (13) | Te2x—O2—Agxi | 84.38 (14) |
O5—Hg—O5i | 174.43 (17) | Ag—O2—Agxi | 65.82 (10) |
O6—Hg—O2v | 123.67 (16) | Hgv—O2—Agxi | 77.03 (10) |
O4i—Hg—O2v | 55.91 (15) | Agxiii—O2—Agxi | 125.03 (13) |
O1ii—Hg—O2v | 142.39 (14) | Te1—O2—Hg | 79.47 (14) |
O3iii—Hg—O2v | 53.19 (13) | Te2x—O2—Hg | 141.7 (2) |
O4iv—Hg—O2v | 77.77 (13) | Ag—O2—Hg | 82.32 (12) |
O5—Hg—O2v | 131.30 (12) | Hgv—O2—Hg | 66.06 (9) |
O5i—Hg—O2v | 53.44 (12) | Agxiii—O2—Hg | 136.08 (14) |
O4iv—Te1—O4 | 180.0 (3) | Agxi—O2—Hg | 59.12 (7) |
O4iv—Te1—O2iv | 91.3 (2) | Te2vii—O3—Te2 | 100.6 (2) |
O4—Te1—O2iv | 88.7 (2) | Te2vii—O3—Hgiii | 111.05 (18) |
O4iv—Te1—O2 | 88.7 (2) | Te2—O3—Hgiii | 114.9 (2) |
O4—Te1—O2 | 91.3 (2) | Te2vii—O3—Agxiv | 90.37 (16) |
O2iv—Te1—O2 | 180.000 (1) | Te2—O3—Agxiv | 154.3 (2) |
O4iv—Te1—O5iv | 90.2 (2) | Hgiii—O3—Agxiv | 81.71 (12) |
O4—Te1—O5iv | 89.8 (2) | Te2vii—O3—Hg | 149.5 (2) |
O2iv—Te1—O5iv | 84.10 (19) | Te2—O3—Hg | 73.09 (13) |
O2—Te1—O5iv | 95.90 (19) | Hgiii—O3—Hg | 98.27 (14) |
O4iv—Te1—O5 | 89.8 (2) | Agxiv—O3—Hg | 85.64 (12) |
O4—Te1—O5 | 90.2 (2) | Te1—O4—Hgvi | 116.7 (2) |
O2iv—Te1—O5 | 95.90 (19) | Te1—O4—Agxiii | 125.5 (2) |
O2—Te1—O5 | 84.10 (19) | Hgvi—O4—Agxiii | 98.71 (19) |
O5iv—Te1—O5 | 180.000 (1) | Te1—O4—Hgiv | 108.1 (2) |
O1—Te2—O6 | 99.2 (2) | Hgvi—O4—Hgiv | 101.70 (19) |
O1—Te2—O5 | 94.2 (2) | Agxiii—O4—Hgiv | 103.02 (16) |
O6—Te2—O5 | 90.5 (2) | Te1—O4—Ag | 74.65 (15) |
O1—Te2—O3vii | 92.3 (2) | Hgvi—O4—Ag | 103.70 (18) |
O6—Te2—O3vii | 168.5 (2) | Agxiii—O4—Ag | 56.82 (10) |
O5—Te2—O3vii | 88.3 (2) | Hgiv—O4—Ag | 149.61 (15) |
O1—Te2—O2viii | 89.9 (2) | Te1—O5—Te2 | 131.8 (2) |
O6—Te2—O2viii | 90.8 (2) | Te1—O5—Hg | 100.05 (19) |
O5—Te2—O2viii | 175.48 (19) | Te2—O5—Hg | 82.44 (16) |
O3vii—Te2—O2viii | 89.60 (19) | Te1—O5—Hgvi | 78.24 (16) |
O1—Te2—O3 | 170.9 (2) | Te2—O5—Hgvi | 94.73 (18) |
O6—Te2—O3 | 89.2 (2) | Hg—O5—Hgvi | 174.43 (17) |
O5—Te2—O3 | 89.15 (19) | Te1—O5—Ag | 96.73 (16) |
O3vii—Te2—O3 | 79.4 (2) | Te2—O5—Ag | 131.3 (2) |
O2viii—Te2—O3 | 86.52 (19) | Hg—O5—Ag | 85.07 (12) |
O6ix—Ag—O1ii | 106.04 (16) | Hgvi—O5—Ag | 100.36 (13) |
O6ix—Ag—O1x | 114.97 (17) | Te1—O5—Hgix | 151.49 (19) |
O1ii—Ag—O1x | 137.17 (15) | Te2—O5—Hgix | 74.59 (13) |
O6ix—Ag—O4xi | 105.34 (17) | Hg—O5—Hgix | 93.58 (12) |
O1ii—Ag—O4xi | 102.20 (16) | Hgvi—O5—Hgix | 90.26 (11) |
O1x—Ag—O4xi | 79.00 (15) | Ag—O5—Hgix | 59.43 (7) |
O6ix—Ag—O2 | 116.14 (16) | Te1—O5—Agxiii | 68.25 (13) |
O1ii—Ag—O2 | 87.14 (15) | Te2—O5—Agxiii | 142.2 (2) |
O1x—Ag—O2 | 64.53 (14) | Hg—O5—Agxiii | 130.36 (13) |
O4xi—Ag—O2 | 133.03 (15) | Hgvi—O5—Agxiii | 54.08 (7) |
O6ix—Ag—O3xii | 70.90 (16) | Ag—O5—Agxiii | 51.21 (6) |
O1ii—Ag—O3xii | 62.66 (14) | Hgix—O5—Agxiii | 83.82 (9) |
O1x—Ag—O3xii | 142.52 (14) | Te2—O6—Hg | 115.9 (2) |
O4xi—Ag—O3xii | 64.24 (14) | Te2—O6—Agii | 131.0 (2) |
O2—Ag—O3xii | 149.31 (14) | Hg—O6—Agii | 111.2 (2) |
O6ix—Ag—O5 | 73.14 (15) | Te2—O6—Agviii | 69.86 (14) |
O1ii—Ag—O5 | 72.12 (14) | Hg—O6—Agviii | 165.9 (2) |
O1x—Ag—O5 | 107.82 (13) | Agii—O6—Agviii | 67.68 (12) |
O4xi—Ag—O5 | 173.08 (14) | Te2—O6—Hgiii | 80.02 (16) |
O2—Ag—O5 | 51.78 (13) | Hg—O6—Hgiii | 97.22 (17) |
O3xii—Ag—O5 | 109.13 (12) | Agii—O6—Hgiii | 81.55 (14) |
Te2—O1—Agix | 107.8 (2) | Agviii—O6—Hgiii | 96.47 (11) |
Te2—O1—Agviii | 101.9 (2) | Te2—O6—Hgix | 74.94 (16) |
Agix—O1—Agviii | 88.40 (15) | Hg—O6—Hgix | 111.64 (18) |
Te2—O1—Hgix | 131.2 (2) | Agii—O6—Hgix | 99.96 (15) |
Agix—O1—Hgix | 119.2 (2) | Agviii—O6—Hgix | 56.13 (8) |
Agviii—O1—Hgix | 92.14 (16) | Hgiii—O6—Hgix | 147.86 (13) |
Te2—O1—Hgvi | 78.63 (15) |
Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, y−1/2, −z+3/2; (iii) −x, −y+1, −z+1; (iv) −x+1, −y+2, −z+1; (v) −x+1, −y+1, −z+1; (vi) x, y+1, z; (vii) −x, −y+2, −z+1; (viii) x−1, y, z; (ix) −x+1/2, y+1/2, −z+3/2; (x) x+1, y, z; (xi) −x+3/2, y−1/2, −z+3/2; (xii) x+1/2, −y+3/2, z+1/2; (xiii) −x+3/2, y+1/2, −z+3/2; (xiv) x−1/2, −y+3/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | Ag2Hg2(TeO4)3 |
Mr | 1191.72 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 295 |
a, b, c (Å) | 6.4664 (6), 6.1623 (5), 13.0851 (11) |
β (°) | 94.548 (2) |
V (Å3) | 519.77 (8) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 41.48 |
Crystal size (mm) | 0.15 × 0.03 × 0.02 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD diffractometer |
Absorption correction | Numerical (HABITUS; Herrendorf, 1997) |
Tmin, Tmax | 0.078, 0.683 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5772, 1573, 1366 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.714 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.024, 0.052, 1.03 |
No. of reflections | 1573 |
No. of parameters | 88 |
Δρmax, Δρmin (e Å−3) | 1.97, −1.44 |
Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ATOMS (Dowty, 2004), SHELXL97.
Hg—O6 | 2.059 (5) | Te2—O5 | 1.958 (4) |
Hg—O4i | 2.068 (5) | Te2—O3v | 1.964 (5) |
Hg—O1ii | 2.464 (4) | Te2—O2vi | 1.970 (4) |
Hg—O3iii | 2.717 (5) | Te2—O3 | 1.981 (4) |
Hg—O4iv | 2.782 (5) | Ag—O6vii | 2.330 (5) |
Hg—O5 | 2.975 (5) | Ag—O1ii | 2.410 (5) |
Te1—O4 | 1.910 (5) | Ag—O1viii | 2.450 (5) |
Te1—O2 | 1.945 (4) | Ag—O4ix | 2.576 (5) |
Te1—O5 | 1.952 (5) | Ag—O2 | 2.589 (5) |
Te2—O1 | 1.840 (5) | Ag—O3x | 2.824 (5) |
Te2—O6 | 1.880 (5) | ||
O6—Hg—O4i | 176.2 (2) | O5—Te2—O3 | 89.15 (19) |
O4—Te1—O2iv | 88.7 (2) | O3v—Te2—O3 | 79.4 (2) |
O4—Te1—O2 | 91.3 (2) | O2vi—Te2—O3 | 86.52 (19) |
O4—Te1—O5iv | 89.8 (2) | O6vii—Ag—O1ii | 106.04 (16) |
O2—Te1—O5iv | 95.90 (19) | O6vii—Ag—O1viii | 114.97 (17) |
O4—Te1—O5 | 90.2 (2) | O1ii—Ag—O1viii | 137.17 (15) |
O2—Te1—O5 | 84.10 (19) | O6vii—Ag—O4ix | 105.34 (17) |
O1—Te2—O6 | 99.2 (2) | O1ii—Ag—O4ix | 102.20 (16) |
O1—Te2—O5 | 94.2 (2) | O1viii—Ag—O4ix | 79.00 (15) |
O6—Te2—O5 | 90.5 (2) | O6vii—Ag—O2 | 116.14 (16) |
O1—Te2—O3v | 92.3 (2) | O1ii—Ag—O2 | 87.14 (15) |
O6—Te2—O3v | 168.5 (2) | O1viii—Ag—O2 | 64.53 (14) |
O5—Te2—O3v | 88.3 (2) | O4ix—Ag—O2 | 133.03 (15) |
O1—Te2—O2vi | 89.9 (2) | O6vii—Ag—O3x | 70.90 (16) |
O6—Te2—O2vi | 90.8 (2) | O1ii—Ag—O3x | 62.66 (14) |
O5—Te2—O2vi | 175.48 (19) | O1viii—Ag—O3x | 142.52 (14) |
O3v—Te2—O2vi | 89.60 (19) | O4ix—Ag—O3x | 64.24 (14) |
O1—Te2—O3 | 170.9 (2) | O2—Ag—O3x | 149.31 (14) |
O6—Te2—O3 | 89.2 (2) |
Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, y−1/2, −z+3/2; (iii) −x, −y+1, −z+1; (iv) −x+1, −y+2, −z+1; (v) −x, −y+2, −z+1; (vi) x−1, y, z; (vii) −x+1/2, y+1/2, −z+3/2; (viii) x+1, y, z; (ix) −x+3/2, y−1/2, −z+3/2; (x) x+1/2, −y+3/2, z+1/2. |
The recent interest in compounds that contain silver and mercury in the crystal structure arose from the discovery of the rare secondary alteration mineral tillmannsite with its empirical formula (Ag3Hg)(As,V)O4 (Sarp et al., 2003). Its crystal structure contains the heretofore unknown tetrahedral silver–mercury cluster cation [Ag3Hg]3+, with Ag and Hg atoms statistically distributed over one crystallographic site and a metal–metal distance of about 2.75 Å. This cluster is of particular interest because of its peculiar electronic situation, which might be described as two-electron–four-center (2 e4c) bonding. Other compounds with tetrahedral cluster cations formed by statistically distributed Ag and Hg atoms include the vanadates (Ag3Hg)(VO4), which is isotypic with tillmannsite, and (Ag2Hg2)3(VO4)4, as well as the mercurate arsenate (Ag2Hg2)2(HgO2)(AsO4)2 (Weil et al., 2005). The last two compounds comprise cluster cations with composition [Ag2Hg2]4+ but similar metal–metal distances of about 2.75 Å and likewise 2 e4c bonding. Other notable interactions between the metal centers Ag and Hg are realised in the isotypic compounds AgHg2(PO4) (Masse et al., 1978) and AgHg2(AsO4) (Weil, 2003). In these structures, double tetrahedra with composition [Ag2Hg4]6+ and Ag—Hg, Ag—Ag and Hg—Hg separations of about 2.85, 2.90 and 2.64 Å, respectively, are observed. Besides all these compounds with tetrahedral metal cluster cations, structures comprising triangular [AgHg2]3+ cluster cations are also known to exist. They are realised in the silver mercury nitrates (AgHg2)(NO3)3 and (AgHg2)Hg(NO3)5 (Nockemann et al., 2004), as well as in the trifluoromethanesulfonate [(AgHg2)(µ-dppm)3](O3SCF3)3 (dppm is diphenylphosphinomethane) (Knoepfler et al., 1995). The structural unit of the [AgHg2]3+ clusters observed in these compounds is roughly characterized by Hg–Hg distances between 2.54 and 2.66 Å, and two Ag–Hg distances between 2.74 and 2.90 Å. In search of other representatives that contain silver–mercury cluster cations, systematic investigations of crystal growth under hydrothermal conditions were undertaken in the systems Ag–Hg–X–O(–H) with X = P, As, Se and V (Weil, 2003; Weil et al., 2005). The crystal structure of the compound Ag2Hg2(TeO4)3, obtained during these experiments when X = Te, is reported in this article.
The structure of Ag2Hg2(TeO4)3 contains one Ag, one Hg, two Te and six O atoms in the asymmetric unit. Except atom Te1, which shows 1 symmetry (Wyckoff notation 2c), all other atoms occupy general positions. The main building blocks of the structure are [TeO6] octahedra, and considerably distorted [AgO6] and [HgO6] polyhedra. The [TeO6] octahedra are condensed to build chains with an overall composition of {TeO4}2− that extend parallel to the a axis. Adjacent tellurate chains are linked by 1∞[AgO4/1O2/2] chains that extend parallel to the b axis. The Hg atoms situated in between the two types of chains complete the three-dimensional setup (Fig. 1).
Both Te atoms display a distorted octahedral coordination by O atoms. Two [Te2O6] octahedra share a common edge to form [Te22O10] dimers. One dimer is connected to two neighboring [Te1O6] octahedra by sharing corner atoms, as displayed in Fig. 2. The scatter within the Te—O distances, ranging from 1.840 (5) to 1.981 (4) Å, mirrors the different types of O atoms present in the anionic entity. While the terminal atoms O4 (Te1), O1 and O6 (Te2) have the shortest Te—O contacts (mean Te–Oterminal = 1.885 Å), the bridging atoms O2 (Te1 and Te2), O5 (Te1 and Te2) and O3 (Te2 and Te2) show considerably longer Te—O bonds (mean Te—Obridging = 1.958 Å). The overall mean Te—O distances for both Te atoms, Te1—O = 1.936 Å and Te2–O = 1.932 Å, are nearly the same and are in very good agreement with the values observed for other structures containing [TeO6] units. For reviews of the crystal chemistry of oxotellurate(VI) compounds see, for example, Kratochvíl & Jenšovský (1986) and Levason (1997 or ?? 1991). The resulting 1∞[(Te(1)O2/1O4/2)({Te(2)O2/1O2/2}2O4/2)] chain has an identical arrangement to that of the tellurate chain recently observed in the structure of disilver(I) oxotellurate(VI), Ag2TeO4, (Klein et al., 2005). These authors have also discussed in detail the relationship between the 1∞[(TeO2/1O4/2)({TeO2/1O2/2}2O4/2)] chain and sections of the rutile structure type.
The metal atoms of the title compound are situated intermediate between the polyanionic chains and interconnect the tellurate units into a three-dimensional framework. Unlike the aforementioned silver–mercury compounds comprising the metal cluster cations, the Ag and Hg atoms in Ag2Hg2(TeO4)3 show no bonding interactions and are well separated [shortest distances of Ag···Ag = 3.3882 (5) Å, Hg···Ag = 3.5391 (7) Å and Hg···Hg = 3.7876 (5) Å].
Mercury(II) oxo compounds and their unique crystal chemistry have been discussed in detail in the past (Grdenić, 1965; Aurivillius, 1965; Müller-Buschbaum, 1995). The most peculiar structural unit of many of these compounds is the pronounced linear coordination of HgII, with two short Hg—O distances ranging from ca 2.02 to 2.20 Å. If all Hg—O distances less than 3.0 Å are being considered as bonding interactions, more remote O atoms are located at significantly longer distances and augment the coordination sphere under formation of distorted (2 + x)-coordination polyhedra (x can range from 2 to 8), x = 4 being the most frequently observed polyhedron (tetragonal flattened or elongated octahedron). A similar situation is observed for the Hg atom in Ag2Hg2(TeO4)3. The two closely bonded O atoms O6 and O4 have a mean distance of Hg—Oshort = 2.064 Å and a nearly linear O6—Hg—O4 angle of 176.2 (2)°. The next nearest O atom is located at a distance of 2.464 (4) Å, whereas three more distant O atoms have contacts greater than 2.7 Å (Fig. 3a). The overall mean Hg—O distance under consideration of coordination number 6 for the Hg atom is 2.511 Å, which is in good agreement with other oxocompounds containing (2 + 4)-coordinated Hg atoms.
A recent review on the peculiarities of the crystal chemistry of oxoargentates and silver oxometallates has been given by Müller-Buschbaum (2004). In various oxocompounds, the AgI cation shows no preference for a certain coordination figure. Therefore, very different [AgOx] coordination polyhedra with coordination numbers (CNS) ranging from 2, for linearly coordinated Ag, up to 12 are realised. The Ag atom in Ag2Hg2(TeO4)3 is surrounded by six O atoms (Fig. 3b) at distances ranging from 2.330 (5) to 2.824 (5) Å. The resulting [AgO6] polyhedron is considerably distorted and difficult to derive from the geometry of an octahedron. However, the mean Ag—O distance of 2.530 Å is comparable to that of other silver compounds that contain Ag in a distorted octahedral environment (Weil, 2003; Klein & Jansen, 2005) and is in excellent agreement with the value of 2.53 Å calculated from the sum of the radii for six-coordinated Ag+ and O2− given by Shannon (1976).
The coordination numbers of the O atoms are 3 (O2, O5 and O6) and 4 (O1, O3 and O4), with corresponding distorted trigonal and tetrahedral coordination polyhedra. Results from the bond valence sum calculations (Brown, 2002), using the parameters of Brese & O'Keeffe (1991), are in good agreement with the expected values for monovalent Ag, divalent Hg and hexavalent Te [Hg (including all distances < 3.0 Å) 2.14, Ag (including all distances < 3.0 Å) 1.02, Te1 5.72, Te2 5.82, O1 (CN = 4) 1.91, O2 (CN = 3) 1.93, O3 (CN = 4) 1.93, O4 (CN = 4) 2.04, O5 (CN = 3) 1.87 and O6 (CN = 3) 2.16].