Zharchikhite, AlF(OH)2: a novel structure type related to α-PbO2 (original) (raw)
The crystal structure of zharchikhite, AlF(OH)2, from the Zharchikhinskoe deposit (Buryatia, Russia) is solved here using single-crystal X-ray diffraction. The mineral is monoclinic, space group P_21/c_, a = 5.1788 (4), b = 7.8386 (4), c = 5.1624 (4) Å, β = 116.276 (10)°, V = 187.91 (3) Å3 and Z = 4. Zharchikhite demonstrates a novel structure type roughly related to the α-PbO2 structure type and different from other compounds of the Al–F–OH system. The crystal structure of zharchikhite is based on the octahedral pseudoframework built from zigzag chains of edge-sharing AlF2(OH)4 octahedra; adjacent chains are linked via F vertices and the pseudoframework contains wide channels.
Supporting information
CCDC reference: 2312527
Crystal data
| AlFH2O2 | F(000) = 160 |
|---|---|
| M r = 80.00 | _D_x = 2.828 Mg m−3 |
| Monoclinic, _P_21/c | Mo _K_α radiation, λ = 0.71073 Å |
| a = 5.1788 (4) Å | Cell parameters from 1113 reflections |
| b = 7.8386 (4) Å | θ = 4.4–30.6° |
| c = 5.1624 (4) Å | µ = 0.74 mm−1 |
| β = 116.276 (10)° | T = 293 K |
| V = 187.91 (3) Å3 | Irregular, colorless |
| Z = 4 | 0.26 × 0.26 × 0.14 mm |
Data collection
| Xcalibur, Sapphire3 diffractometer | 463 independent reflections |
|---|---|
| Radiation source: fine-focus sealed X-ray tube | 445 reflections with I > 2σ(I) |
| Detector resolution: 16.0630 pixels mm-1 | _R_int = 0.016 |
| ω scans | θmax = 28.3°, θmin = 4.4° |
| Absorption correction: multi-scan | h = −6→6 |
| _T_min = 0.762, _T_max = 1.000 | k = −9→10 |
| 1342 measured reflections | l = −5→6 |
Refinement
| Refinement on _F_2 | 2 restraints |
|---|---|
| Least-squares matrix: full | Hydrogen site location: difference Fourier map |
| _R_[_F_2 > 2σ(_F_2)] = 0.025 | All H-atom parameters refined |
| wR(_F_2) = 0.063 | w = 1/[σ2(F_o2) + (0.0363_P)2 + 0.0333_P_] where P = (_F_o2 + 2_F_c2)/3 |
| S = 1.19 | (Δ/σ)max = 0.001 |
| 463 reflections | Δρmax = 0.37 e Å−3 |
| 45 parameters | Δρmin = −0.60 e Å−3 |
Special details
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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
| | x | y | z | _U_iso*/_U_eq | | | ----- | ------------ | ------------- | -------------- | ------------ | | Al | 0.74234 (6) | 0.08386 (4) | 0.98407 (7) | 0.00435 (18) | | O1 | 0.34054 (18) | 0.06447 (10) | 0.77768 (18) | 0.0064 (2) | | H1 | 0.275 (3) | 0.054 (2) | 0.598 (2) | 0.023 (4)* | | O2 | 0.85510 (19) | −0.09266 (10) | 0.80783 (19) | 0.0062 (2) | | H2 | 0.781 (3) | −0.1920 (14) | 0.782 (4) | 0.023 (4)* | | F | 0.72572 (14) | 0.26973 (9) | 0.19524 (15) | 0.0084 (2) |
Atomic displacement parameters (Å2)
| | _U_11 | _U_22 | _U_33 | _U_12 | _U_13 | _U_23 | | | ------- | ---------- | ---------- | ---------- | ------------ | ------------ | ------------- | | Al | 0.0041 (3) | 0.0048 (2) | 0.0043 (3) | 0.00009 (10) | 0.00200 (18) | −0.00002 (11) | | O1 | 0.0058 (4) | 0.0086 (4) | 0.0040 (4) | −0.0006 (3) | 0.0015 (3) | 0.0007 (3) | | O2 | 0.0052 (4) | 0.0057 (4) | 0.0072 (4) | −0.0010 (3) | 0.0022 (4) | −0.0013 (3) | | F | 0.0097 (4) | 0.0080 (4) | 0.0082 (4) | −0.0001 (2) | 0.0046 (3) | −0.0031 (2) |
Geometric parameters (Å, º)
| Al—Fi | 1.8443 (7) | Al—O2 | 1.8852 (9) |
|---|---|---|---|
| Al—Fii | 1.8531 (7) | Al—Aliii | 2.9020 (6) |
| Al—O1iii | 1.8752 (9) | Al—Aliv | 2.9136 (6) |
| Al—O2iv | 1.8767 (9) | O1—H1 | 0.838 (9) |
| Al—O1 | 1.8776 (9) | O2—H2 | 0.852 (9) |
| Fi—Al—Fii | 89.352 (16) | O2iv—Al—Aliii | 138.91 (3) |
| Fi—Al—O1iii | 91.03 (3) | O1—Al—Aliii | 39.32 (3) |
| Fii—Al—O1iii | 165.73 (4) | O2—Al—Aliii | 98.94 (3) |
| Fi—Al—O2iv | 87.90 (3) | Fi—Al—Aliv | 127.18 (3) |
| Fii—Al—O2iv | 94.70 (4) | Fii—Al—Aliv | 92.29 (2) |
| O1iii—Al—O2iv | 99.56 (4) | O1iii—Al—Aliv | 98.81 (3) |
| Fi—Al—O1 | 93.98 (4) | O2iv—Al—Aliv | 39.34 (3) |
| Fii—Al—O1 | 87.05 (4) | O1—Al—Aliv | 138.83 (3) |
| O1iii—Al—O1 | 78.70 (4) | O2—Al—Aliv | 39.13 (3) |
| O2iv—Al—O1 | 177.45 (4) | Aliii—Al—Aliv | 125.87 (2) |
| Fi—Al—O2 | 166.07 (4) | Aliii—O1—Al | 101.30 (4) |
| Fii—Al—O2 | 88.86 (4) | Aliii—O1—H1 | 124.8 (12) |
| O1iii—Al—O2 | 94.08 (4) | Al—O1—H1 | 115.9 (10) |
| O2iv—Al—O2 | 78.48 (4) | Aliv—O2—Al | 101.52 (4) |
| O1—Al—O2 | 99.73 (4) | Aliv—O2—H2 | 115.5 (11) |
| Fi—Al—Aliii | 93.24 (2) | Al—O2—H2 | 122.1 (10) |
| Fii—Al—Aliii | 126.36 (3) | Alv—F—Alvi | 165.26 (5) |
| O1iii—Al—Aliii | 39.38 (3) |
Symmetry codes: (i) x, y, z+1; (ii) x, −y+1/2, z+1/2; (iii) −x+1, −y, −z+2; (iv) −x+2, −y, −z+2; (v) x, y, z_−1; (vi) x, −_y+1/2, _z_−1/2.
Hydrogen-bond geometry (Å, º)
| D_—H···_A | _D_—H | H···A | D_···_A | D_—H···_A |
|---|---|---|---|---|
| O1—H1···O2vii | 0.84 (1) | 1.92 (1) | 2.7386 (14) | 165 (2) |
| O2—H2···O1viii | 0.85 (1) | 1.99 (1) | 2.8370 (12) | 172 (1) |
Symmetry codes: (vii) −x+1, −y, −z+1; (viii) −x+1, y_−1/2, −_z+3/2.