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Crystals of K2[SiF6] 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 Fm\bar{3}m) 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

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520615007507/xk5019sup1.cif
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2052520615007507/xk5019Isup2.hkl
Contains datablock I

CCDC reference: 1059988

Computing details top

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).

(I) top
Crystal data top
F6K2SiMo Kα radiation, λ = 0.71073 Å
Mr = 220.29Cell parameters from 2659 reflections
Cubic, Fm3mθ = 5.0–40.0°
a = 8.1345 (8) ŵ = 2.02 mm1
V = 538.26 (9) Å3T = 298 K
Z = 4Cube, colourless
F(000) = 4240.26 × 0.26 × 0.26 mm
Dx = 2.718 Mg m3
Data collection top
Bruker Kappa ApexII area detector
diffractometer
116 independent reflections
Radiation source: fine-focus sealed tube113 reflections with I > 2σ(I)
Triumph monochromatorRint = 0.014
ω scansθmax = 40.3°, θmin = 5.0°
Absorption correction: multi-scan
SADABS-2008/1 (Sheldrick, 2008)
h = 1412
Tmin = 0.706, Tmax = 0.748k = 1314
3622 measured reflectionsl = 1412
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.016Secondary 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 reflectionsΔρmax = 0.28 e Å3
6 parametersΔρmin = 0.30 e Å3
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
xyzUiso*/Ueq
F0.20675 (11)0.00000.00000.0292 (2)
Si0.00000.00000.00000.01660 (16)
K0.25000.25000.25000.02396 (14)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F0.0163 (3)0.0356 (3)0.0356 (3)0.0000.0000.000
Si0.01660 (16)0.01660 (16)0.01660 (16)0.0000.0000.000
K0.02396 (14)0.02396 (14)0.02396 (14)0.0000.0000.000
Geometric parameters (Å, º) top
F—Si1.6818 (9)Si—Kx3.5223 (3)
F—K2.8974 (3)Si—Ki3.5223 (3)
F—Ki2.8974 (3)K—Fv2.8974 (3)
F—Kii2.8974 (3)K—Fviii2.8974 (3)
F—Kiii2.8974 (3)K—Fxi2.8974 (3)
Si—Fiv1.6818 (9)K—Fxii2.8974 (3)
Si—Fv1.6818 (9)K—Fxiii2.8974 (3)
Si—Fvi1.6818 (9)K—Fxiv2.8974 (3)
Si—Fvii1.6818 (9)K—Fii2.8974 (3)
Si—Fviii1.6818 (9)K—Fxv2.8974 (3)
Si—Kvii3.5223 (3)K—Fxvi2.8974 (3)
Si—K3.5223 (3)K—Fxvii2.8974 (3)
Si—Kii3.5223 (3)K—Fiii2.8974 (3)
Si—Kix3.5223 (3)
Si—F—K96.974 (18)Kvii—Si—Ki70.5
Si—F—Ki96.974 (18)K—Si—Ki109.5
K—F—Ki166.05 (4)Kii—Si—Ki70.5
Si—F—Kii96.974 (18)Kix—Si—Ki109.5
K—F—Kii89.155 (4)Kx—Si—Ki109.5
Ki—F—Kii89.155 (4)F—K—Fv48.47 (3)
Si—F—Kiii96.974 (18)F—K—Fviii48.47 (3)
K—F—Kiii89.155 (4)Fv—K—Fviii48.46 (3)
Ki—F—Kiii89.155 (4)F—K—Fxi119.513 (2)
Kii—F—Kiii166.05 (4)Fv—K—Fxi166.05 (4)
Fiv—Si—Fv180.0Fviii—K—Fxi119.513 (2)
Fiv—Si—Fvi90.0F—K—Fxii119.513 (2)
Fv—Si—Fvi90.0Fv—K—Fxii119.513 (2)
Fiv—Si—Fvii90.0Fviii—K—Fxii166.05 (4)
Fv—Si—Fvii90.0Fxi—K—Fxii71.21 (3)
Fvi—Si—Fvii90.0F—K—Fxiii166.05 (4)
Fiv—Si—Fviii90.0Fv—K—Fxiii119.513 (2)
Fv—Si—Fviii90.0Fviii—K—Fxiii119.513 (2)
Fvi—Si—Fviii180.0Fxi—K—Fxiii71.21 (3)
Fvii—Si—Fviii90.0Fxii—K—Fxiii71.21 (3)
Fiv—Si—F90.0F—K—Fxiv71.21 (3)
Fv—Si—F90.0Fv—K—Fxiv90.845 (4)
Fvi—Si—F90.0Fviii—K—Fxiv119.513 (2)
Fvii—Si—F180.0Fxi—K—Fxiv90.845 (4)
Fviii—Si—F90.0Fxii—K—Fxiv48.46 (3)
Fiv—Si—Kvii54.740 (10)Fxiii—K—Fxiv119.513 (2)
Fv—Si—Kvii125.3F—K—Fii90.845 (4)
Fvi—Si—Kvii54.740 (10)Fv—K—Fii119.513 (2)
Fvii—Si—Kvii54.740 (10)Fviii—K—Fii71.21 (3)
Fviii—Si—Kvii125.3Fxi—K—Fii48.46 (3)
F—Si—Kvii125.3Fxii—K—Fii119.513 (2)
Fiv—Si—K125.3Fxiii—K—Fii90.845 (4)
Fv—Si—K54.740 (10)Fxiv—K—Fii119.513 (2)
Fvi—Si—K125.3F—K—Fxv119.514 (2)
Fvii—Si—K125.3Fv—K—Fxv71.21 (3)
Fviii—Si—K54.740 (10)Fviii—K—Fxv90.845 (4)
F—Si—K54.740 (10)Fxi—K—Fxv119.513 (2)
Kvii—Si—K180.0Fxii—K—Fxv90.845 (4)
Fiv—Si—Kii54.740 (10)Fxiii—K—Fxv48.46 (3)
Fv—Si—Kii125.3Fxiv—K—Fxv119.513 (2)
Fvi—Si—Kii125.3Fii—K—Fxv119.513 (2)
Fvii—Si—Kii125.3F—K—Fxvi71.21 (3)
Fviii—Si—Kii54.740 (10)Fv—K—Fxvi119.513 (2)
F—Si—Kii54.740 (10)Fviii—K—Fxvi90.845 (4)
Kvii—Si—Kii109.5Fxi—K—Fxvi48.46 (3)
K—Si—Kii70.5Fxii—K—Fxvi90.845 (4)
Fiv—Si—Kix54.740 (10)Fxiii—K—Fxvi119.513 (2)
Fv—Si—Kix125.3Fxiv—K—Fxvi71.21 (3)
Fvi—Si—Kix125.3Fii—K—Fxvi48.46 (3)
Fvii—Si—Kix54.740 (10)Fxv—K—Fxvi166.05 (4)
Fviii—Si—Kix54.740 (10)F—K—Fxvii119.514 (2)
F—Si—Kix125.3Fv—K—Fxvii90.845 (4)
Kvii—Si—Kix70.5Fviii—K—Fxvii71.21 (3)
K—Si—Kix109.5Fxi—K—Fxvii90.845 (4)
Kii—Si—Kix70.5Fxii—K—Fxvii119.513 (2)
Fiv—Si—Kx125.3Fxiii—K—Fxvii48.46 (3)
Fv—Si—Kx54.740 (10)Fxiv—K—Fxvii166.05 (4)
Fvi—Si—Kx54.740 (10)Fii—K—Fxvii71.21 (3)
Fvii—Si—Kx54.740 (10)Fxv—K—Fxvii48.46 (3)
Fviii—Si—Kx125.3Fxvi—K—Fxvii119.513 (2)
F—Si—Kx125.3F—K—Fiii90.845 (4)
Kvii—Si—Kx70.5Fv—K—Fiii71.21 (3)
K—Si—Kx109.5Fviii—K—Fiii119.513 (2)
Kii—Si—Kx180.0Fxi—K—Fiii119.513 (2)
Kix—Si—Kx109.5Fxii—K—Fiii48.46 (3)
Fiv—Si—Ki54.740 (10)Fxiii—K—Fiii90.845 (4)
Fv—Si—Ki125.3Fxiv—K—Fiii48.46 (3)
Fvi—Si—Ki54.740 (10)Fii—K—Fiii166.05 (4)
Fvii—Si—Ki125.3Fxv—K—Fiii71.21 (3)
Fviii—Si—Ki125.3Fxvi—K—Fiii119.513 (2)
F—Si—Ki54.740 (10)Fxvii—K—Fiii119.513 (2)
Symmetry codes: (i) x, y1/2, z1/2; (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) x1/2, y, z1/2; (x) x1/2, y1/2, 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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