Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199012184/br1259sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270199012184/br1259Isup2.hkl |
Potassium (156 mg; 4.0 mmol; Merck, 99%) was reacted with a powdered mixture of Al2O3 (204 mg, 2.0 mmol; Merck, p.a.??), Sb2O3 (292 mg, 1.0 mmol; Merck, p.a.) and Sb2O5 (323 mg, 1.0 mmol; ABCR, 99%) in a corundum crucible under an argon (99.99%) atmosphere. The mixture was heated up to 1050 K at a rate of 100 K h−1 and then cooled to 590 K at 5 K h−1 and from 590 K to room temperature at 15 K h−1. The title compound crystallizes in clear thin plates of hexagonal shape. The X-ray powder patterns of the samples can be indexed with the single-crystal data of the title compound and show only weak reflections of corundum, Sb2O3 and additional unknown compounds.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: HELENA (Spek, 1993); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP (Johnson, 1968) and DRAWxtl (Finger & Kroeker, 1997); software used to prepare material for publication: SHELXL97.
K2[Al2Sb2O7] | Dx = 3.664 Mg m−3 |
Mr = 487.66 | Mo Kα radiation, λ = 0.71070 Å |
Trigonal, P3m1 | Cell parameters from 25 reflections |
a = 5.6325 (8) Å | θ = 6.3–23.8° |
c = 8.045 (2) Å | µ = 7.25 mm−1 |
V = 221.04 (7) Å3 | T = 293 K |
Z = 1 | Hexagonal plate, colourless |
F(000) = 222 | 0.10 × 0.07 × 0.03 mm |
Enraf-Nonius CAD-4 diffractometer | 319 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.085 |
Graphite monochromator | θmax = 32.4°, θmin = 4.2° |
ω/2θ scans | h = −8→8 |
Absorption correction: ψ-scans (North et al., 1968) | k = −8→8 |
Tmin = 0.589, Tmax = 0.805 | l = −12→0 |
1691 measured reflections | 3 standard reflections every 7200 min |
342 independent reflections | intensity decay: none |
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)] = 0.018 | w = 1/[σ2(Fo2) + (0.0191P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.044 | (Δ/σ)max < 0.001 |
S = 1.14 | Δρmax = 1.28 e Å−3 |
342 reflections | Δρmin = −0.81 e Å−3 |
19 parameters | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.014 (3) |
K2[Al2Sb2O7] | Z = 1 |
Mr = 487.66 | Mo Kα radiation |
Trigonal, P3m1 | µ = 7.25 mm−1 |
a = 5.6325 (8) Å | T = 293 K |
c = 8.045 (2) Å | 0.10 × 0.07 × 0.03 mm |
V = 221.04 (7) Å3 |
Enraf-Nonius CAD-4 diffractometer | 319 reflections with I > 2σ(I) |
Absorption correction: ψ-scans (North et al., 1968) | Rint = 0.085 |
Tmin = 0.589, Tmax = 0.805 | 3 standard reflections every 7200 min |
1691 measured reflections | intensity decay: none |
342 independent reflections |
R[F2 > 2σ(F2)] = 0.018 | 19 parameters |
wR(F2) = 0.044 | 0 restraints |
S = 1.14 | Δρmax = 1.28 e Å−3 |
342 reflections | Δρmin = −0.81 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 | ||
K1 | 1/3 | 2/3 | 0.58969 (14) | 0.01743 (18) | |
Sb1 | 1/3 | 2/3 | 0.15516 (3) | 0.00913 (12) | |
Al1 | 0 | 0 | 0.21158 (14) | 0.0081 (2) | |
O1 | 0.16874 (17) | 0.83126 (17) | 0.2895 (2) | 0.0152 (3) | |
O2 | 0 | 0 | 0 | 0.0206 (9) |
U11 | U22 | U33 | U12 | U13 | U23 | |
K1 | 0.0176 (2) | 0.0176 (2) | 0.0172 (4) | 0.00879 (12) | 0 | 0 |
Sb1 | 0.00929 (13) | 0.00929 (13) | 0.00879 (15) | 0.00465 (6) | 0 | 0 |
Al1 | 0.0068 (3) | 0.0068 (3) | 0.0107 (5) | 0.00340 (14) | 0 | 0 |
O1 | 0.0194 (6) | 0.0194 (6) | 0.0153 (6) | 0.0159 (7) | −0.0001 (3) | 0.0001 (3) |
O2 | 0.0257 (14) | 0.0257 (14) | 0.0104 (17) | 0.0129 (7) | 0 | 0 |
K1—O1 | 2.900 (2) | Sb1—K1ix | 3.8456 (8) |
K1—O1i | 2.900 (2) | Sb1—K1iv | 3.8456 (8) |
K1—O1ii | 2.900 (2) | Sb1—K1vi | 3.8456 (9) |
K1—O1iii | 2.9792 (8) | Al1—O2 | 1.7022 (12) |
K1—O1iv | 2.9792 (8) | Al1—O1i | 1.7616 (18) |
K1—O1v | 2.9792 (9) | Al1—O1x | 1.7616 (18) |
K1—O1vi | 2.9792 (8) | Al1—O1xi | 1.7616 (18) |
K1—O1vii | 2.9792 (9) | Al1—K1ix | 3.6237 (10) |
K1—O1viii | 2.9792 (8) | Al1—K1xii | 3.6237 (10) |
K1—Sb1 | 3.4959 (14) | Al1—K1vi | 3.6237 (10) |
K1—K1ix | 3.5577 (10) | O1—Al1xiii | 1.7616 (18) |
K1—K1vi | 3.5578 (11) | O1—K1iv | 2.9792 (8) |
Sb1—O1ii | 1.9358 (17) | O1—K1vi | 2.9792 (8) |
Sb1—O1i | 1.9358 (17) | O2—Al1xiv | 1.7022 (12) |
Sb1—O1 | 1.9358 (17) | ||
O1—K1—O1i | 57.31 (6) | O1v—K1—K1vi | 51.75 (3) |
O1—K1—O1ii | 57.31 (6) | O1vi—K1—K1vi | 51.75 (3) |
O1i—K1—O1ii | 57.31 (6) | O1vii—K1—K1vi | 151.34 (3) |
O1—K1—O1iii | 79.64 (6) | O1viii—K1—K1vi | 97.96 (3) |
O1i—K1—O1iii | 136.62 (3) | Sb1—K1—K1vi | 66.07 (3) |
O1ii—K1—O1iii | 105.54 (4) | K1ix—K1—K1vi | 104.67 (4) |
O1—K1—O1iv | 105.54 (4) | O1ii—Sb1—O1i | 91.84 (7) |
O1i—K1—O1iv | 136.62 (3) | O1ii—Sb1—O1 | 91.84 (7) |
O1ii—K1—O1iv | 79.64 (6) | O1i—Sb1—O1 | 91.84 (7) |
O1iii—K1—O1iv | 55.65 (7) | O1ii—Sb1—K1 | 56.05 (5) |
O1—K1—O1v | 79.64 (6) | O1i—Sb1—K1 | 56.05 (5) |
O1i—K1—O1v | 105.54 (4) | O1—Sb1—K1 | 56.05 (5) |
O1ii—K1—O1v | 136.62 (3) | O1ii—Sb1—K1ix | 49.546 (15) |
O1iii—K1—O1v | 57.18 (7) | O1i—Sb1—K1ix | 49.546 (16) |
O1iv—K1—O1v | 109.90 (4) | O1—Sb1—K1ix | 113.79 (5) |
O1—K1—O1vi | 105.54 (4) | K1—Sb1—K1ix | 57.738 (16) |
O1i—K1—O1vi | 79.64 (6) | O1ii—Sb1—K1iv | 49.546 (15) |
O1ii—K1—O1vi | 136.62 (3) | O1i—Sb1—K1iv | 113.79 (5) |
O1iii—K1—O1vi | 109.90 (4) | O1—Sb1—K1iv | 49.546 (16) |
O1iv—K1—O1vi | 141.92 (8) | K1—Sb1—K1iv | 57.738 (16) |
O1v—K1—O1vi | 55.65 (7) | K1ix—Sb1—K1iv | 94.16 (2) |
O1—K1—O1vii | 136.62 (3) | O1ii—Sb1—K1vi | 113.79 (6) |
O1i—K1—O1vii | 105.54 (4) | O1i—Sb1—K1vi | 49.546 (15) |
O1ii—K1—O1vii | 79.64 (6) | O1—Sb1—K1vi | 49.546 (15) |
O1iii—K1—O1vii | 109.90 (4) | K1—Sb1—K1vi | 57.738 (17) |
O1iv—K1—O1vii | 57.18 (7) | K1ix—Sb1—K1vi | 94.16 (2) |
O1v—K1—O1vii | 141.92 (8) | K1iv—Sb1—K1vi | 94.16 (2) |
O1vi—K1—O1vii | 109.90 (4) | O2—Al1—O1i | 110.86 (7) |
O1—K1—O1viii | 136.62 (3) | O2—Al1—O1x | 110.85 (7) |
O1i—K1—O1viii | 79.64 (6) | O1i—Al1—O1x | 108.05 (7) |
O1ii—K1—O1viii | 105.54 (4) | O2—Al1—O1xi | 110.86 (7) |
O1iii—K1—O1viii | 141.92 (8) | O1i—Al1—O1xi | 108.05 (7) |
O1iv—K1—O1viii | 109.90 (4) | O1x—Al1—O1xi | 108.05 (7) |
O1v—K1—O1viii | 109.90 (4) | O2—Al1—K1ix | 116.18 (3) |
O1vi—K1—O1viii | 57.18 (7) | O1i—Al1—K1ix | 54.80 (2) |
O1vii—K1—O1viii | 55.65 (7) | O1x—Al1—K1ix | 132.96 (8) |
O1—K1—Sb1 | 33.62 (4) | O1xi—Al1—K1ix | 54.80 (2) |
O1i—K1—Sb1 | 33.62 (4) | O2—Al1—K1xii | 116.18 (3) |
O1ii—K1—Sb1 | 33.62 (4) | O1i—Al1—K1xii | 132.96 (8) |
O1iii—K1—Sb1 | 109.04 (4) | O1x—Al1—K1xii | 54.80 (2) |
O1iv—K1—Sb1 | 109.04 (4) | O1xi—Al1—K1xii | 54.80 (2) |
O1v—K1—Sb1 | 109.04 (4) | K1ix—Al1—K1xii | 102.01 (3) |
O1vi—K1—Sb1 | 109.04 (4) | O2—Al1—K1vi | 116.18 (3) |
O1vii—K1—Sb1 | 109.04 (4) | O1i—Al1—K1vi | 54.80 (2) |
O1viii—K1—Sb1 | 109.04 (4) | O1x—Al1—K1vi | 54.80 (2) |
O1—K1—K1ix | 99.69 (6) | O1xi—Al1—K1vi | 132.96 (8) |
O1i—K1—K1ix | 53.78 (3) | K1ix—Al1—K1vi | 102.01 (3) |
O1ii—K1—K1ix | 53.78 (3) | K1xii—Al1—K1vi | 102.01 (3) |
O1iii—K1—K1ix | 151.34 (3) | Al1xiii—O1—Sb1 | 125.19 (10) |
O1iv—K1—K1ix | 97.96 (3) | Al1xiii—O1—K1 | 144.48 (9) |
O1v—K1—K1ix | 151.34 (3) | Sb1—O1—K1 | 90.33 (6) |
O1vi—K1—K1ix | 97.96 (3) | Al1xiii—O1—K1iv | 96.30 (4) |
O1vii—K1—K1ix | 51.75 (3) | Sb1—O1—K1iv | 100.82 (4) |
O1viii—K1—K1ix | 51.75 (3) | K1—O1—K1iv | 74.47 (4) |
Sb1—K1—K1ix | 66.07 (3) | Al1xiii—O1—K1vi | 96.30 (4) |
O1—K1—K1vi | 53.78 (3) | Sb1—O1—K1vi | 100.82 (4) |
O1i—K1—K1vi | 53.78 (3) | K1—O1—K1vi | 74.47 (4) |
O1ii—K1—K1vi | 99.69 (6) | K1iv—O1—K1vi | 141.92 (8) |
O1iii—K1—K1vi | 97.96 (3) | Al1—O2—Al1xiv | 180.0 |
O1iv—K1—K1vi | 151.34 (3) |
Symmetry codes: (i) −y+1, x−y+1, z; (ii) −x+y, −x+1, z; (iii) x−y+1, x+1, −z+1; (iv) −x+1, −y+2, −z+1; (v) y−1, −x+y, −z+1; (vi) −x, −y+1, −z+1; (vii) y, −x+y, −z+1; (viii) x−y+1, x, −z+1; (ix) −x+1, −y+1, −z+1; (x) −x+y−1, −x, z; (xi) x, y−1, z; (xii) −x, −y, −z+1; (xiii) x, y+1, z; (xiv) −x, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | K2[Al2Sb2O7] |
Mr | 487.66 |
Crystal system, space group | Trigonal, P3m1 |
Temperature (K) | 293 |
a, c (Å) | 5.6325 (8), 8.045 (2) |
V (Å3) | 221.04 (7) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 7.25 |
Crystal size (mm) | 0.10 × 0.07 × 0.03 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | ψ-scans (North et al., 1968) |
Tmin, Tmax | 0.589, 0.805 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1691, 342, 319 |
Rint | 0.085 |
(sin θ/λ)max (Å−1) | 0.753 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.018, 0.044, 1.14 |
No. of reflections | 342 |
No. of parameters | 19 |
Δρmax, Δρmin (e Å−3) | 1.28, −0.81 |
Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, HELENA (Spek, 1993), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP (Johnson, 1968) and DRAWxtl (Finger & Kroeker, 1997), SHELXL97.
K1—O1 | 2.900 (2) | Al1—O2 | 1.7022 (12) |
K1—O1i | 2.9792 (8) | Al1—O1iii | 1.7616 (18) |
Sb1—O1ii | 1.9358 (17) | ||
O1ii—Sb1—O1iii | 91.84 (7) | Al1v—O1—Sb1 | 125.19 (10) |
O2—Al1—O1iii | 110.86 (7) | Al1—O2—Al1vi | 180.0 |
O1iii—Al1—O1iv | 108.05 (7) |
Symmetry codes: (i) x−y+1, x+1, −z+1; (ii) −x+y, −x+1, z; (iii) −y+1, x−y+1, z; (iv) −x+y−1, −x, z; (v) x, y+1, z; (vi) −x, −y, −z. |
The title compound (Fig. 1) is isotypic with the thallium vanadate Tl4V2O7 (= Tl2I[Tl2IV2VO7]; Jouanneaux et al., 1992), the structure of which was determined from powder diffraction data. K2Pb2Ge2O7 (Bassi & Lajzerowicz, 1965) is probably isotypic, but was first described as crystallizing in the subgroup P3. A symmetry check (Le Page, 1987) and transformation to the standard setting with the help of the program STRUCTURE TIDY (Gelato & Parthé, 1987) shows the isotypic nature of K2Pb2Ge2O7 and the title compound.
The Al atoms in K2Al2Sb2O7 are located on the edges of the unit cell (Fig. 2) and are coordinated by four O atoms in an approximately regular tetrahedral environment, with Al—O distances of 1.702 (1) (Al—O2, × 1) and 1.762 (2) Å (Al—O1, × 3) and O—Al—O angles ranging from 108.1 (1) to 110.9 (1)° (shown as tetrahedra in Fig. 2). Two AlO4 tetrahedra are connected by a common O2 atom to form linear [Al2O7] dimers with a staggered conformation of the six O1 ligands (Fig. 1). These dimers are connected by Sb3+ ions to form layers perpendicular to the threefold axis. The Sb atoms are coordinated by three O ligands in a Ψ-tetrahedral coordination, with an Sb—O distance of 1.936 (2) Å and an O—Sb—O angle of 91.8 (1)°. The corresponding distances and angles in CsSbO2 (Hirschle & Röhr, 1998), Cs4Sb2O5 (Hirschle & Röhr, 1999) and Na3SbO3 (Stöver & Hoppe, 1980) are comparable to these values. They clearly indicate the stereochemical activity of the antimony(III) lone pair, which in K2Al2Sb2O7 points towards the centre of the layered [Al2Sb2O7]2− anions running perpendicular to the (001) direction. The anions are bounded by oxygen kagome (3.6.3.6) nets stacked in the sequence A—B. The K+ cations are intercalated between the [Al2Sb2O7]2− layers, with a resulting coordination number of nine and K—O distances ranging from 2.900 (2) to 2.979 (1) Å.