Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010102087X/br1350sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010102087X/br1350Isup2.hkl |
To synthesize Pb2HgCrO6, a mixture of HgO, PbO2 and elemental Cr (molar ratio 1:2:1), under an elevated oxygen pressure of 11 MPa, was annealed for 120 h at 773 K in silver crucibles placed in stainless steel autoclaves (Linke & Jansen, 1997) using H2O (2 ml) as an accelerator. Single crystals of Pb2HgCrO6 were formed.
Refinement was also carried out in space group P1, but did not lead to better agreement factors and was therefore discarded.
Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-RED (Stoe & Cie, 2001); program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1998-2000).
Fig. 1. A projection onto ab of the structure of Pb2HgCrO6. The [CrO4]2- tetrahedra are shown. | |
Fig. 2. Views of the two environments of the Pb2+ ions in Pb2HgCrO6. |
Pb2HgCrO6 | Z = 2 |
Mr = 762.98 | F(000) = 632 |
Triclinic, P1 | Dx = 7.651 Mg m−3 |
a = 6.505 (2) Å | Mo Kα radiation, λ = 0.71069 Å |
b = 7.201 (3) Å | Cell parameters from 8070 reflections |
c = 7.605 (3) Å | θ = 2.6–24.5° |
α = 91.82 (3)° | µ = 75.35 mm−1 |
β = 92.17 (3)° | T = 293 K |
γ = 111.33 (3)° | Prismatic, red |
V = 331.2 (2) Å3 | 0.20 × 0.05 × 0.02 mm |
Stoe IPDS II diffractometer | 1838 independent reflections |
Radiation source: fine-focus sealed tube | 1583 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.070 |
image plate scans | θmax = 29.5°, θmin = 2.7° |
Absorption correction: numerical (Coppens, 1970) | h = −9→7 |
Tmin = 0.011, Tmax = 0.081 | k = −9→9 |
3475 measured reflections | l = −10→10 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.049 | w = 1/[σ2(Fo2) + (0.0857P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.127 | (Δ/σ)max < 0.001 |
S = 0.97 | Δρmax = 3.68 e Å−3 |
1838 reflections | Δρmin = −3.30 e Å−3 |
92 parameters | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0073 (7) |
Pb2HgCrO6 | γ = 111.33 (3)° |
Mr = 762.98 | V = 331.2 (2) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.505 (2) Å | Mo Kα radiation |
b = 7.201 (3) Å | µ = 75.35 mm−1 |
c = 7.605 (3) Å | T = 293 K |
α = 91.82 (3)° | 0.20 × 0.05 × 0.02 mm |
β = 92.17 (3)° |
Stoe IPDS II diffractometer | 1838 independent reflections |
Absorption correction: numerical (Coppens, 1970) | 1583 reflections with I > 2σ(I) |
Tmin = 0.011, Tmax = 0.081 | Rint = 0.070 |
3475 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | 92 parameters |
wR(F2) = 0.127 | 0 restraints |
S = 0.97 | Δρmax = 3.68 e Å−3 |
1838 reflections | Δρmin = −3.30 e Å−3 |
Experimental. measured with Stoe IPDS II; 1. run: phi=0; omega=0–180; delta omega=1; time=1 min 2. run: phi=90; omega=0–180; delta omega=1; time=1 min detector distance= 100 mm Integration: Coefficient A=12.0 Coefficient B=2.0 EMS=0.010 |
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 | ||
Hg1 | 0.68673 (8) | 0.70067 (9) | 0.63551 (7) | 0.03091 (19) | |
Pb1 | −0.21924 (9) | 0.25922 (8) | 0.13343 (8) | 0.0320 (2) | |
Pb2 | 0.17992 (9) | 0.74491 (8) | 0.39612 (7) | 0.0317 (2) | |
Cr1 | 0.7086 (4) | 0.7665 (4) | 0.1477 (3) | 0.0301 (5) | |
O1 | 0.463 (2) | 0.6478 (18) | 0.2086 (19) | 0.049 (3) | |
O2 | 0.0538 (16) | 0.3898 (15) | 0.3672 (14) | 0.031 (2) | |
O3 | 0.844 (2) | 0.9460 (17) | 0.2982 (15) | 0.039 (2) | |
O4 | 0.4134 (16) | 0.7651 (17) | 0.6257 (14) | 0.035 (2) | |
O5 | −0.1528 (19) | 0.6160 (18) | 0.1271 (16) | 0.042 (3) | |
O6 | 0.686 (2) | 0.8686 (18) | −0.0350 (15) | 0.042 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Hg1 | 0.0240 (3) | 0.0354 (3) | 0.0366 (3) | 0.0149 (2) | 0.0000 (2) | 0.0017 (2) |
Pb1 | 0.0300 (3) | 0.0332 (3) | 0.0344 (3) | 0.0134 (2) | 0.0011 (2) | 0.0004 (2) |
Pb2 | 0.0265 (3) | 0.0341 (3) | 0.0364 (3) | 0.0136 (2) | −0.0018 (2) | 0.0036 (2) |
Cr1 | 0.0287 (11) | 0.0302 (10) | 0.0339 (12) | 0.0138 (8) | −0.0007 (9) | 0.0015 (9) |
O1 | 0.037 (6) | 0.036 (5) | 0.068 (8) | 0.007 (5) | 0.009 (6) | 0.010 (5) |
O2 | 0.021 (4) | 0.034 (5) | 0.043 (5) | 0.018 (4) | −0.005 (4) | −0.002 (4) |
O3 | 0.044 (6) | 0.035 (5) | 0.043 (6) | 0.020 (5) | 0.000 (5) | 0.000 (4) |
O4 | 0.021 (5) | 0.054 (6) | 0.040 (5) | 0.026 (4) | −0.004 (4) | 0.002 (5) |
O5 | 0.028 (5) | 0.043 (6) | 0.049 (7) | 0.008 (4) | −0.009 (5) | −0.007 (5) |
O6 | 0.052 (7) | 0.043 (6) | 0.036 (6) | 0.024 (5) | 0.002 (5) | 0.007 (5) |
Hg1—O4 | 1.993 (9) | Pb2—O2 | 2.384 (10) |
Hg1—O2i | 2.019 (9) | Pb2—O2iv | 2.395 (11) |
Hg1—O1i | 2.673 (9) | Pb2—O1 | 2.642 (14) |
Hg1—O6ii | 2.749 (9) | Pb2—O5 | 2.795 (14) |
Hg1—O3 | 3.150 (9) | Pb2—O3vii | 3.109 (14) |
Hg1—O3iii | 3.193 (9) | Pb2—O3viii | 3.215 (14) |
Hg1—O1 | 3.459 (9) | Pb2—O4viii | 3.571 (14) |
Pb1—O4iv | 2.240 (11) | Pb2—Pb1iv | 3.5791 (16) |
Pb1—O2 | 2.375 (10) | Cr1—O1 | 1.609 (12) |
Pb1—O5 | 2.448 (12) | Cr1—O6 | 1.619 (11) |
Pb1—O3v | 2.765 (12) | Cr1—O5ix | 1.650 (13) |
Pb1—O6vi | 2.893 (12) | Cr1—O3 | 1.661 (12) |
Pb1—O6v | 2.895 (12) | O2—Hg1i | 2.019 (9) |
Pb1—O5vi | 3.080 (12) | O2—Pb2iv | 2.395 (11) |
Pb1—O1vi | 3.209 (12) | O4—Pb1iv | 2.240 (11) |
Pb1—Pb2iv | 3.5791 (16) | O5—Cr1vii | 1.650 (13) |
Pb2—O4 | 2.236 (9) | ||
O4—Hg1—O2i | 174.5 (4) | O6—Cr1—O3 | 108.5 (6) |
O4iv—Pb1—O2 | 75.7 (4) | O5ix—Cr1—O3 | 108.0 (5) |
O4iv—Pb1—O5 | 90.6 (4) | Cr1—O1—Pb2 | 134.6 (7) |
O2—Pb1—O5 | 78.9 (3) | Hg1i—O2—Pb1 | 116.2 (5) |
O4—Pb2—O2 | 93.6 (4) | Hg1i—O2—Pb2 | 110.3 (4) |
O4—Pb2—O2iv | 75.4 (4) | Pb1—O2—Pb2 | 111.8 (4) |
O2—Pb2—O2iv | 71.5 (4) | Hg1i—O2—Pb2iv | 112.1 (4) |
O4—Pb2—O1 | 85.2 (4) | Pb1—O2—Pb2iv | 97.2 (4) |
O2—Pb2—O1 | 72.0 (4) | Pb2—O2—Pb2iv | 108.5 (4) |
O2iv—Pb2—O1 | 137.1 (3) | Hg1—O4—Pb2 | 129.4 (5) |
O1—Cr1—O6 | 107.5 (7) | Hg1—O4—Pb1iv | 119.8 (5) |
O1—Cr1—O5ix | 111.0 (6) | Pb2—O4—Pb1iv | 106.2 (4) |
O6—Cr1—O5ix | 112.2 (6) | Cr1vii—O5—Pb1 | 138.9 (6) |
O1—Cr1—O3 | 109.5 (7) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, y, z+1; (iii) −x+2, −y+2, −z+1; (iv) −x, −y+1, −z+1; (v) x−1, y−1, z; (vi) −x, −y+1, −z; (vii) x−1, y, z; (viii) −x+1, −y+2, −z+1; (ix) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | Pb2HgCrO6 |
Mr | 762.98 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 6.505 (2), 7.201 (3), 7.605 (3) |
α, β, γ (°) | 91.82 (3), 92.17 (3), 111.33 (3) |
V (Å3) | 331.2 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 75.35 |
Crystal size (mm) | 0.20 × 0.05 × 0.02 |
Data collection | |
Diffractometer | Stoe IPDS II diffractometer |
Absorption correction | Numerical (Coppens, 1970) |
Tmin, Tmax | 0.011, 0.081 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3475, 1838, 1583 |
Rint | 0.070 |
(sin θ/λ)max (Å−1) | 0.694 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.127, 0.97 |
No. of reflections | 1838 |
No. of parameters | 92 |
Δρmax, Δρmin (e Å−3) | 3.68, −3.30 |
Computer programs: X-AREA (Stoe & Cie, 2001), X-AREA, X-RED (Stoe & Cie, 2001), SIR97 (Altomare et al., 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1998-2000).
Hg1—O4 | 1.993 (9) | Pb1—O1vi | 3.209 (12) |
Hg1—O2i | 2.019 (9) | Pb2—O4 | 2.236 (9) |
Hg1—O1i | 2.673 (9) | Pb2—O2 | 2.384 (10) |
Hg1—O6ii | 2.749 (9) | Pb2—O2iv | 2.395 (11) |
Hg1—O3 | 3.150 (9) | Pb2—O1 | 2.642 (14) |
Hg1—O3iii | 3.193 (9) | Pb2—O5 | 2.795 (14) |
Hg1—O1 | 3.459 (9) | Pb2—O3vii | 3.109 (14) |
Pb1—O4iv | 2.240 (11) | Pb2—O3viii | 3.215 (14) |
Pb1—O2 | 2.375 (10) | Pb2—O4viii | 3.571 (14) |
Pb1—O5 | 2.448 (12) | Cr1—O1 | 1.609 (12) |
Pb1—O3v | 2.765 (12) | Cr1—O6 | 1.619 (11) |
Pb1—O6vi | 2.893 (12) | Cr1—O5ix | 1.650 (13) |
Pb1—O6v | 2.895 (12) | Cr1—O3 | 1.661 (12) |
Pb1—O5vi | 3.080 (12) | ||
O4—Hg1—O2i | 174.5 (4) | O1—Cr1—O6 | 107.5 (7) |
O4iv—Pb1—O2 | 75.7 (4) | O1—Cr1—O5ix | 111.0 (6) |
O4iv—Pb1—O5 | 90.6 (4) | O6—Cr1—O5ix | 112.2 (6) |
O2—Pb1—O5 | 78.9 (3) | O1—Cr1—O3 | 109.5 (7) |
O4—Pb2—O2 | 93.6 (4) | O6—Cr1—O3 | 108.5 (6) |
O4—Pb2—O2iv | 75.4 (4) | O5ix—Cr1—O3 | 108.0 (5) |
O2—Pb2—O2iv | 71.5 (4) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, y, z+1; (iii) −x+2, −y+2, −z+1; (iv) −x, −y+1, −z+1; (v) x−1, y−1, z; (vi) −x, −y+1, −z; (vii) x−1, y, z; (viii) −x+1, −y+2, −z+1; (ix) x+1, y, z. |
Pb2HgCrO6 was first obtained as a by-product of different syntheses aiming to produce ternary silver oxides in steel autoclaves with perchloric acid as an accelerator (Curda et al., 2001). Subsequently, single crystals of Pb2HgCrO6 have been prepared by solid state reaction of a mixture of HgO, PbO2 and elemental Cr (molar ratio 1:2:1) under an elevated oxygen pressure.
The structure of Pb2HgCrO6 can be described as consisting of three basic building units: isolated [CrO4]2- tetrahedra and nearly linear [HgO2]2- dumbbells form layers of composition [HgCrO6]4- which are intercalated with corrugated pseudohexagonal Pb2+ layers perpendicular to the [110] direction (Fig. 1).
The Pb2+ is stereochemically active. Every Pb2+ has a first coordination sphere formed by three O atoms at distances ranging from 2.24 to 2.45 Å. The second coordination sphere is formed by five further O atoms at distances of 2.64–3.66 Å (Table 1; Fig. 2).
Bond valence sums for the cations calculated according to Brese & O'Keeffe (1991) are 6.16 for Cr, 1.98 for Hg, and 2.14 and 2.21 for Pb. While for the O atoms O1, O5 and O6 the bond valence sums are within the normal range (2.09, 2.11 and 1.96, respectively), for O2 (2.22), O3 (1.79) and O4 (2.30), higher deviations from the ideal value are observed.