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Crystals of K
2[SiF
6] were grown in agar gel, silica gel and jelly. Crystals grown in agar gel or jelly exhibit birefringence and consist of six double refracting growth sectors, each having the shape of a tetragonal pyramid. Nevertheless, the structure of the crystals from agar gel could be refined as cubic (space group
) with a weighted
R factor of 0.043. The amount of birefringence was estimated by the Senarmont compensation method and the rotating polarizer method.
Supporting information
CCDC reference: 1059988
Data collection: Apex2 (Bruker, 2010); cell refinement: SAINT V7.68A (Bruker, 2010); data reduction: SAINT V7.68A (Bruker, 2010), SADABS2008/1 (Sheldrick, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).
Crystal data top
F6K2Si | Mo Kα radiation, λ = 0.71073 Å |
Mr = 220.29 | Cell parameters from 2659 reflections |
Cubic, Fm3m | θ = 5.0–40.0° |
a = 8.1345 (8) Å | µ = 2.02 mm−1 |
V = 538.26 (9) Å3 | T = 298 K |
Z = 4 | Cube, colourless |
F(000) = 424 | 0.26 × 0.26 × 0.26 mm |
Dx = 2.718 Mg m−3 | |
Data collection top
Bruker Kappa ApexII area detector diffractometer | 116 independent reflections |
Radiation source: fine-focus sealed tube | 113 reflections with I > 2σ(I) |
Triumph monochromator | Rint = 0.014 |
ω scans | θmax = 40.3°, θmin = 5.0° |
Absorption correction: multi-scan SADABS-2008/1 (Sheldrick, 2008) | h = −14→12 |
Tmin = 0.706, Tmax = 0.748 | k = −13→14 |
3622 measured reflections | l = −14→12 |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.016 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.043 | w = 1/[σ2(Fo2) + (0.0189P)2 + 0.3956P] where P = (Fo2 + 2Fc2)/3 |
S = 1.12 | (Δ/σ)max < 0.001 |
116 reflections | Δρmax = 0.28 e Å−3 |
6 parameters | Δρmin = −0.30 e Å−3 |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
F | 0.20675 (11) | 0.0000 | 0.0000 | 0.0292 (2) | |
Si | 0.0000 | 0.0000 | 0.0000 | 0.01660 (16) | |
K | 0.2500 | 0.2500 | 0.2500 | 0.02396 (14) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
F | 0.0163 (3) | 0.0356 (3) | 0.0356 (3) | 0.000 | 0.000 | 0.000 |
Si | 0.01660 (16) | 0.01660 (16) | 0.01660 (16) | 0.000 | 0.000 | 0.000 |
K | 0.02396 (14) | 0.02396 (14) | 0.02396 (14) | 0.000 | 0.000 | 0.000 |
Geometric parameters (Å, º) top
F—Si | 1.6818 (9) | Si—Kx | 3.5223 (3) |
F—K | 2.8974 (3) | Si—Ki | 3.5223 (3) |
F—Ki | 2.8974 (3) | K—Fv | 2.8974 (3) |
F—Kii | 2.8974 (3) | K—Fviii | 2.8974 (3) |
F—Kiii | 2.8974 (3) | K—Fxi | 2.8974 (3) |
Si—Fiv | 1.6818 (9) | K—Fxii | 2.8974 (3) |
Si—Fv | 1.6818 (9) | K—Fxiii | 2.8974 (3) |
Si—Fvi | 1.6818 (9) | K—Fxiv | 2.8974 (3) |
Si—Fvii | 1.6818 (9) | K—Fii | 2.8974 (3) |
Si—Fviii | 1.6818 (9) | K—Fxv | 2.8974 (3) |
Si—Kvii | 3.5223 (3) | K—Fxvi | 2.8974 (3) |
Si—K | 3.5223 (3) | K—Fxvii | 2.8974 (3) |
Si—Kii | 3.5223 (3) | K—Fiii | 2.8974 (3) |
Si—Kix | 3.5223 (3) | | |
| | | |
Si—F—K | 96.974 (18) | Kvii—Si—Ki | 70.5 |
Si—F—Ki | 96.974 (18) | K—Si—Ki | 109.5 |
K—F—Ki | 166.05 (4) | Kii—Si—Ki | 70.5 |
Si—F—Kii | 96.974 (18) | Kix—Si—Ki | 109.5 |
K—F—Kii | 89.155 (4) | Kx—Si—Ki | 109.5 |
Ki—F—Kii | 89.155 (4) | F—K—Fv | 48.47 (3) |
Si—F—Kiii | 96.974 (18) | F—K—Fviii | 48.47 (3) |
K—F—Kiii | 89.155 (4) | Fv—K—Fviii | 48.46 (3) |
Ki—F—Kiii | 89.155 (4) | F—K—Fxi | 119.513 (2) |
Kii—F—Kiii | 166.05 (4) | Fv—K—Fxi | 166.05 (4) |
Fiv—Si—Fv | 180.0 | Fviii—K—Fxi | 119.513 (2) |
Fiv—Si—Fvi | 90.0 | F—K—Fxii | 119.513 (2) |
Fv—Si—Fvi | 90.0 | Fv—K—Fxii | 119.513 (2) |
Fiv—Si—Fvii | 90.0 | Fviii—K—Fxii | 166.05 (4) |
Fv—Si—Fvii | 90.0 | Fxi—K—Fxii | 71.21 (3) |
Fvi—Si—Fvii | 90.0 | F—K—Fxiii | 166.05 (4) |
Fiv—Si—Fviii | 90.0 | Fv—K—Fxiii | 119.513 (2) |
Fv—Si—Fviii | 90.0 | Fviii—K—Fxiii | 119.513 (2) |
Fvi—Si—Fviii | 180.0 | Fxi—K—Fxiii | 71.21 (3) |
Fvii—Si—Fviii | 90.0 | Fxii—K—Fxiii | 71.21 (3) |
Fiv—Si—F | 90.0 | F—K—Fxiv | 71.21 (3) |
Fv—Si—F | 90.0 | Fv—K—Fxiv | 90.845 (4) |
Fvi—Si—F | 90.0 | Fviii—K—Fxiv | 119.513 (2) |
Fvii—Si—F | 180.0 | Fxi—K—Fxiv | 90.845 (4) |
Fviii—Si—F | 90.0 | Fxii—K—Fxiv | 48.46 (3) |
Fiv—Si—Kvii | 54.740 (10) | Fxiii—K—Fxiv | 119.513 (2) |
Fv—Si—Kvii | 125.3 | F—K—Fii | 90.845 (4) |
Fvi—Si—Kvii | 54.740 (10) | Fv—K—Fii | 119.513 (2) |
Fvii—Si—Kvii | 54.740 (10) | Fviii—K—Fii | 71.21 (3) |
Fviii—Si—Kvii | 125.3 | Fxi—K—Fii | 48.46 (3) |
F—Si—Kvii | 125.3 | Fxii—K—Fii | 119.513 (2) |
Fiv—Si—K | 125.3 | Fxiii—K—Fii | 90.845 (4) |
Fv—Si—K | 54.740 (10) | Fxiv—K—Fii | 119.513 (2) |
Fvi—Si—K | 125.3 | F—K—Fxv | 119.514 (2) |
Fvii—Si—K | 125.3 | Fv—K—Fxv | 71.21 (3) |
Fviii—Si—K | 54.740 (10) | Fviii—K—Fxv | 90.845 (4) |
F—Si—K | 54.740 (10) | Fxi—K—Fxv | 119.513 (2) |
Kvii—Si—K | 180.0 | Fxii—K—Fxv | 90.845 (4) |
Fiv—Si—Kii | 54.740 (10) | Fxiii—K—Fxv | 48.46 (3) |
Fv—Si—Kii | 125.3 | Fxiv—K—Fxv | 119.513 (2) |
Fvi—Si—Kii | 125.3 | Fii—K—Fxv | 119.513 (2) |
Fvii—Si—Kii | 125.3 | F—K—Fxvi | 71.21 (3) |
Fviii—Si—Kii | 54.740 (10) | Fv—K—Fxvi | 119.513 (2) |
F—Si—Kii | 54.740 (10) | Fviii—K—Fxvi | 90.845 (4) |
Kvii—Si—Kii | 109.5 | Fxi—K—Fxvi | 48.46 (3) |
K—Si—Kii | 70.5 | Fxii—K—Fxvi | 90.845 (4) |
Fiv—Si—Kix | 54.740 (10) | Fxiii—K—Fxvi | 119.513 (2) |
Fv—Si—Kix | 125.3 | Fxiv—K—Fxvi | 71.21 (3) |
Fvi—Si—Kix | 125.3 | Fii—K—Fxvi | 48.46 (3) |
Fvii—Si—Kix | 54.740 (10) | Fxv—K—Fxvi | 166.05 (4) |
Fviii—Si—Kix | 54.740 (10) | F—K—Fxvii | 119.514 (2) |
F—Si—Kix | 125.3 | Fv—K—Fxvii | 90.845 (4) |
Kvii—Si—Kix | 70.5 | Fviii—K—Fxvii | 71.21 (3) |
K—Si—Kix | 109.5 | Fxi—K—Fxvii | 90.845 (4) |
Kii—Si—Kix | 70.5 | Fxii—K—Fxvii | 119.513 (2) |
Fiv—Si—Kx | 125.3 | Fxiii—K—Fxvii | 48.46 (3) |
Fv—Si—Kx | 54.740 (10) | Fxiv—K—Fxvii | 166.05 (4) |
Fvi—Si—Kx | 54.740 (10) | Fii—K—Fxvii | 71.21 (3) |
Fvii—Si—Kx | 54.740 (10) | Fxv—K—Fxvii | 48.46 (3) |
Fviii—Si—Kx | 125.3 | Fxvi—K—Fxvii | 119.513 (2) |
F—Si—Kx | 125.3 | F—K—Fiii | 90.845 (4) |
Kvii—Si—Kx | 70.5 | Fv—K—Fiii | 71.21 (3) |
K—Si—Kx | 109.5 | Fviii—K—Fiii | 119.513 (2) |
Kii—Si—Kx | 180.0 | Fxi—K—Fiii | 119.513 (2) |
Kix—Si—Kx | 109.5 | Fxii—K—Fiii | 48.46 (3) |
Fiv—Si—Ki | 54.740 (10) | Fxiii—K—Fiii | 90.845 (4) |
Fv—Si—Ki | 125.3 | Fxiv—K—Fiii | 48.46 (3) |
Fvi—Si—Ki | 54.740 (10) | Fii—K—Fiii | 166.05 (4) |
Fvii—Si—Ki | 125.3 | Fxv—K—Fiii | 71.21 (3) |
Fviii—Si—Ki | 125.3 | Fxvi—K—Fiii | 119.513 (2) |
F—Si—Ki | 54.740 (10) | Fxvii—K—Fiii | 119.513 (2) |
Symmetry codes: (i) x, y−1/2, z−1/2; (ii) −x+1/2, −y+1/2, −z; (iii) −x+1/2, −y, −z+1/2; (iv) −y, −z, −x; (v) y, z, x; (vi) −z, −x, −y; (vii) −x, −y, −z; (viii) z, x, y; (ix) x−1/2, y, z−1/2; (x) x−1/2, y−1/2, z; (xi) y+1/2, z+1/2, x; (xii) z+1/2, x, y+1/2; (xiii) x, y+1/2, z+1/2; (xiv) −y+1/2, −z, −x+1/2; (xv) −z, −x+1/2, −y+1/2; (xvi) −z+1/2, −x+1/2, −y; (xvii) −y, −z+1/2, −x+1/2. |
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