The two-dimensional network topology of the mixed alkali title compound, K1.33Na0.67Si2O5, is found to differ from that of the end-member compositions, Na2Si2O5 and K2Si2O5. The network of the silicate sheet consists of rings with four, six and eight SiO4 tetrahedra. The cations are sandwiched between the silicate sheets.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 150 K
- Mean (i-O) = 0.004 Å
- R factor = 0.043
- wR factor = 0.118
- Data-to-parameter ratio = 11.4
checkCIF/PLATON results
No syntax errors found
Alert level C
ABSTM02_ALERT_3_C The ratio of Tmax/Tmin expected RT(exp) is > 1.10
Absorption corrections should be applied.
Tmin and Tmax expected: 0.609 0.711
RT(exp) = 1.167
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings Differ .... ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............ 0.33 Ratio
PLAT057_ALERT_3_C Correction for Absorption Required RT(exp) ... 1.17
PLAT213_ALERT_2_C Atom O22 has ADP max/min Ratio ............. 3.10 prolat
PLAT213_ALERT_2_C Atom O23 has ADP max/min Ratio ............. 3.60 prolat
PLAT220_ALERT_2_C Large Non-Solvent O Ueq(max)/Ueq(min) ... 2.96 Ratio
PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Si2
PLAT396_ALERT_2_C Deviating Si-O-Si Angle from 150 Deg for O23 165.10 Deg.
Alert level G
CELLZ01_ALERT_1_G Difference between formula and atom_site contents detected.
CELLZ01_ALERT_1_G ALERT: check formula stoichiometry or atom site occupancies.
From the CIF: _cell_formula_units_Z 12
From the CIF: _chemical_formula_sum K1.33 Na0.67 O5 Si2
TEST: Compare cell contents of formula and atom_site data
atom Z*formula cif sites diff
K 15.96 16.00 -0.04
Na 8.04 8.00 0.04
O 60.00 60.00 0.00
Si 24.00 24.00 0.00
0 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
10 ALERT level C = Check and explain
2 ALERT level G = General alerts; check
5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
5 ALERT type 2 Indicator that the structure model may be wrong or deficient
2 ALERT type 3 Indicator that the structure quality may be low
0 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: locally modified CAD-4 Software (Enraf–Nonius, 1989); cell refinement: SET4 (de Boer & Duisenberg, 1984); data reduction: HELENA (Spek, 1997); program(s) used to solve structure: DIRDIF99 (Beurskens et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON.
Potassium sodium phyllosilicate
top
Crystal data top
K1.33Na0.67Si2O5 | F(000) = 1208 |
Mr = 203.64 | Least Squares Treatment of 25 SET4 setting angles. |
Monoclinic, C2/c | Dx = 2.552 Mg m−3 |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 19.6816 (15) Å | Cell parameters from 9 reflections |
b = 7.2656 (6) Å | θ = 10–14° |
c = 12.5710 (15) Å | µ = 1.71 mm−1 |
β = 117.82 (1)° | T = 150 K |
V = 1589.9 (3) Å3 | Block, colorless |
Z = 12 | 0.3 × 0.3 × 0.2 mm |
Data collection top
Enraf–Nonius TurboCAD-4 diffractometer | Rint = 0.068 |
Radiation source: Rotating Anode | θmax = 25°, θmin = 2.3° |
Graphite monochromator | h = −23→8 |
ω scans | k = −8→8 |
2841 measured reflections | l = −13→14 |
1406 independent reflections | 1 standard reflections every 60 min |
1094 reflections with I > 2σ(I) | intensity decay: none |
Refinement top
Refinement on F2 | 6 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.043 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.118 | w = 1/[σ2(Fo2) + (0.0465P)2 + 11.2001P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max = 0.001 |
1406 reflections | Δρmax = 0.65 e Å−3 |
123 parameters | Δρmin = −0.92 e Å−3 |
Special details top
Geometry. Bond distances, angles etc. have been calculated using the rounded
fractional coordinates. All su's are estimated from the variances of the
(full) variance-covariance matrix. The cell e.s.d.'s are taken into account in
the estimation of distances, angles and torsion angles |
Refinement. Refinement on F2 for ALL reflections except those flagged by the user
for potential systematic errors. Weighted R-factors wR and all
goodnesses of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The observed criterion of F2 > σ(F2)
is used only for calculating -R-factor-obs 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 | |
Si1 | 0.15093 (8) | 0.3950 (2) | 0.00188 (12) | 0.0083 (4) | |
Si2 | 0.06654 (8) | 0.7460 (2) | −0.11486 (12) | 0.0085 (4) | |
Si3 | 0.32560 (8) | 0.4508 (2) | 0.11444 (14) | 0.0131 (4) | |
O11 | 0.1430 (2) | 0.3936 (6) | 0.1196 (3) | 0.0219 (12) | |
O12 | 0.2340 (2) | 0.4647 (5) | 0.0170 (3) | 0.0162 (12) | |
O13 | 0.1349 (2) | 0.1899 (6) | −0.0584 (4) | 0.0181 (12) | |
O14 | 0.0870 (2) | 0.5250 (5) | −0.1061 (3) | 0.0114 (10) | |
O21 | 0.0425 (3) | 0.8137 (6) | −0.0203 (4) | 0.0303 (14) | |
O22 | 0.1441 (2) | 0.8450 (6) | −0.1007 (5) | 0.0338 (16) | |
O23 | 0.00000 | 0.7746 (8) | −0.25000 | 0.0305 (17) | |
O31 | 0.3418 (2) | 0.4068 (7) | 0.2448 (3) | 0.0311 (14) | |
K1 | 0.06258 (9) | 0.6274 (2) | 0.16520 (13) | 0.0293 (5) | |
K2 | 0.25138 (8) | 0.3240 (2) | 0.33695 (11) | 0.0246 (4) | |
Na1 | 0.08060 (13) | 0.0864 (3) | 0.09417 (19) | 0.0209 (7) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Si1 | 0.0097 (7) | 0.0067 (7) | 0.0070 (7) | −0.0008 (6) | 0.0027 (6) | 0.0011 (6) |
Si2 | 0.0094 (7) | 0.0073 (7) | 0.0051 (7) | −0.0010 (6) | 0.0003 (6) | 0.0002 (6) |
Si3 | 0.0097 (8) | 0.0075 (7) | 0.0180 (8) | −0.0008 (6) | 0.0030 (6) | −0.0026 (6) |
O11 | 0.026 (2) | 0.027 (2) | 0.015 (2) | 0.005 (2) | 0.0116 (18) | 0.0052 (18) |
O12 | 0.014 (2) | 0.012 (2) | 0.020 (2) | −0.0015 (17) | 0.0057 (17) | 0.0082 (17) |
O13 | 0.016 (2) | 0.011 (2) | 0.028 (2) | −0.0030 (17) | 0.0109 (18) | −0.0073 (18) |
O14 | 0.0137 (19) | 0.0085 (18) | 0.0078 (17) | −0.0016 (16) | 0.0014 (15) | 0.0005 (15) |
O21 | 0.060 (3) | 0.023 (2) | 0.022 (2) | 0.017 (2) | 0.031 (2) | 0.009 (2) |
O22 | 0.017 (2) | 0.010 (2) | 0.074 (4) | −0.0042 (18) | 0.021 (2) | −0.009 (2) |
O23 | 0.039 (3) | 0.012 (3) | 0.012 (3) | 0.0000 | −0.012 (2) | 0.0000 |
O31 | 0.018 (2) | 0.056 (3) | 0.011 (2) | −0.007 (2) | −0.0003 (18) | −0.008 (2) |
K1 | 0.0291 (8) | 0.0260 (8) | 0.0241 (8) | −0.0036 (6) | 0.0052 (6) | 0.0052 (6) |
K2 | 0.0325 (8) | 0.0325 (8) | 0.0125 (6) | 0.0087 (6) | 0.0136 (6) | 0.0084 (6) |
Na1 | 0.0224 (13) | 0.0163 (12) | 0.0138 (11) | −0.0039 (10) | 0.0000 (9) | 0.0042 (9) |
Geometric parameters (Å, º) top
Si1—O11 | 1.559 (4) | K1—O14iv | 2.904 (4) |
Si1—O12 | 1.636 (5) | K1—O13iv | 3.353 (5) |
Si1—O13 | 1.634 (5) | K1—O31v | 2.637 (5) |
Si1—O14 | 1.650 (4) | K2—O11 | 2.614 (4) |
Si2—O14 | 1.647 (4) | K2—O31 | 2.607 (5) |
Si2—O21 | 1.550 (6) | K2—O12iv | 2.884 (4) |
Si2—O22 | 1.620 (5) | K2—O22iv | 2.850 (5) |
Si2—O23 | 1.6024 (16) | K2—O22vi | 2.980 (6) |
Si3—O12 | 1.643 (4) | K2—O12vi | 3.127 (4) |
Si3—O31 | 1.550 (4) | Na1—O11 | 2.495 (5) |
Si3—O13i | 1.630 (5) | Na1—O13 | 2.702 (5) |
Si3—O22ii | 1.638 (5) | Na1—O21vii | 2.356 (5) |
K1—O11 | 2.563 (5) | Na1—O21iii | 2.271 (7) |
K1—O21 | 2.562 (5) | Na1—O31vi | 2.291 (5) |
K1—O14iii | 2.899 (5) | | |
| | | |
O11—Si1—O12 | 115.4 (2) | O12—Si3—O31 | 114.4 (2) |
O11—Si1—O13 | 110.6 (2) | O12—Si3—O13i | 107.2 (2) |
O11—Si1—O14 | 114.1 (2) | O12—Si3—O22ii | 101.1 (2) |
O12—Si1—O13 | 107.6 (2) | O13i—Si3—O31 | 115.1 (3) |
O12—Si1—O14 | 104.8 (2) | O22ii—Si3—O31 | 113.1 (3) |
O13—Si1—O14 | 103.4 (2) | O13i—Si3—O22ii | 104.6 (3) |
O14—Si2—O21 | 114.3 (2) | Si1—O12—Si3 | 139.2 (2) |
O14—Si2—O22 | 103.7 (2) | Si1—O13—Si3i | 138.1 (3) |
O14—Si2—O23 | 104.5 (2) | Si1—O14—Si2 | 133.0 (2) |
O21—Si2—O22 | 112.6 (3) | Si2—O22—Si3ii | 139.6 (3) |
O21—Si2—O23 | 112.4 (2) | Si2—O23—Si2viii | 165.1 (4) |
O22—Si2—O23 | 108.7 (2) | | |
Symmetry codes: (i) −x+1/2, −y+1/2, −z; (ii) −x+1/2, −y+3/2, −z; (iii) −x, −y+1, −z; (iv) x, −y+1, z+1/2; (v) −x+1/2, y+1/2, −z+1/2; (vi) −x+1/2, y−1/2, −z+1/2; (vii) x, y−1, z; (viii) −x, y, −z−1/2. |