Dipotassium hexaaquairon(II) bis(sulfate), K2[Fe(H2O)6](SO4)2, is a member of the isotypic series of Tutton salts with general formula MI2[MII(H2O)6](XO4)2, where X = S, Se or Cr. The structure contains centrosymmetric Fe(H2O)6 octahedra, with an average Fe-O distance of 2.14 (4) Å. Each octahedron is surrounded by isolated SO4 tetrahedra [average S-O distance = 1.483 (15) Å] and distorted KO6(H2O)2 polyhedra with an average K-O distance of 2.96 (15) Å. The polyhedra are linked via common O atoms and a system of medium-strength hydrogen bonds.
Supporting information
Key indicators
- Powder X-ray study
- T = 298 K
- Mean (S-O) = 0.014 Å
- R factor = 0.000
- wR factor = 0.000
- Data-to-parameter ratio = 0.0
checkCIF/PLATON results
No syntax errors found
Alert level C
REFI023_ALERT_1_C _refine_diff_density_max is missing
Maximum value of final difference map (e A-3).
The following tests will not be performed
DIFMN_01,DIFMX_01,DIFMX_02
REFI024_ALERT_1_C _refine_diff_density_min is missing
Minimum value of final difference map (e A-3).
The following tests will not be performed
DIFMN_01,DIFMN_02,DIFMN_03
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
PLAT128_ALERT_4_C Non-standard setting of Space group P21/c .... P21/a
PLAT702_ALERT_1_C Angle Calc 89.1(4), Rep 89.9(4), Dev.. 2.00 Sigma
O6 -FE -O7 3.555 1.555 3.555
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd. # 2
O4 S
0 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
6 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
0 ALERT type 2 Indicator that the structure model may be wrong or deficient
0 ALERT type 3 Indicator that the structure quality may be low
2 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: XRD COMMANDER (Bruker, 2004); cell refinement: TOPAS (Bruker, 2005); program(s) used to solve structure: coordinates taken from isotypic compound; program(s) used to refine structure: TOPAS; molecular graphics: ATOMS (Dowty, 2000); software used to prepare material for publication: TOPAS.
Dipotassium hexaaquairon(II) bis(sulfate)
top
Crystal data top
K2[Fe(H2O)6](SO4)2 | Z = 2 |
Mr = 434.29 | F(000) = 440 |
Monoclinic, P21/a | Non-standard setting of space group P 21/c to adhere to reference data
of other Tutton salts. |
Hall symbol: -P 2yab | Dx = 2.170 Mg m−3 |
a = 9.0766 (3) Å | CuKα radiation, λ = CuKα1a 1.540596
CuKα1b 1.541058
CuKα2a 1.544410
CuKα2b 1.544721
satellites 1.534753 Å |
b = 12.2646 (4) Å | µ = 18.36 mm−1 |
c = 6.1689 (2) Å | T = 298 K |
β = 104.5478 (16)° | Particle morphology: prism |
V = 664.71 (4) Å3 | pale green |
Data collection top
Bruker AXS D8Focus diffractometer | Scan method: step |
Radiation source: sealed X-ray tube | Absorption correction: for a cylinder mounted on the φ axis Sabine et al. (1998) |
Specimen mounting: borosilicate glass capillary | |
Data collection mode: transmission | 2θmin = 5.00°, 2θmax = 155.00°, 2θstep = 0.02° |
Refinement top
Least-squares matrix: full | 0 restraints |
Rp = 5.04 | 0 constraints |
Rwp = 6.40 | H-atom parameters not refined |
Rexp = 6.16 | 1/[Yi] |
R(F2) = 1.03 | (Δ/σ)max = 0.01 |
7501 data points | Background function: Chebychev polynomial |
Profile function: FPA (Cheary & Coelho, 1992) | Preferred orientation correction: Preferred Orientation Spherical Harmonics
Order 4
y00 1
y20 -0.077(12)
y22m -0.039(11)
y22p -0.023(12)
y40 -0.063(17)
y42m -0.018(11)
y42p -0.041(12)
y44m -0.014(12)
y44p -0.011(14) |
95 parameters | |
Special details top
Refinement. Fundamental Parameters Approach with simple axial approximation. Receiving slit
0.1 mm, divergence and antidivergence slit 0.6 mm, axial divergence 12 mm. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Fe | 0 | 0 | 0 | 0.016 (3) | |
K | 0.1325 (5) | 0.3470 (4) | 0.3443 (8) | 0.033 (3) | |
S | 0.4114 (7) | 0.1356 (5) | −0.2731 (10) | 0.022 (3) | |
O1 | 0.2832 (14) | 0.0612 (11) | −0.379 (2) | 0.026 (3) | |
O2 | 0.4111 (16) | 0.2300 (11) | −0.427 (2) | 0.026 (3) | |
O3 | 0.3916 (16) | 0.1690 (11) | −0.051 (2) | 0.026 (3) | |
O4 | 0.5533 (14) | 0.0746 (10) | −0.248 (2) | 0.026 (3) | |
O5 | 0.1769 (14) | 0.1134 (9) | 0.1698 (18) | 0.017 (4) | |
O6 | −0.1717 (13) | 0.1144 (10) | 0.0302 (18) | 0.017 (4) | |
O7 | 0.0021 (14) | 0.0695 (9) | −0.3069 (19) | 0.017 (4) | |
H11 | 0.25 | 0.109 | 0.077 | 0.05 | |
H12 | 0.234 | 0.096 | 0.319 | 0.05 | |
H21 | −0.132 | 0.185 | 0.073 | 0.05 | |
H22 | −0.281 | 0.114 | 0.001 | 0.05 | |
H31 | −0.032 | 0.141 | −0.273 | 0.05 | |
H32 | 0.113 | 0.071 | −0.262 | 0.05 | |
Geometric parameters (Å, º) top
Fe—O5 | 2.183 (11) | K—O3v | 2.844 (13) |
Fe—O5i | 2.183 (11) | K—O4ii | 3.238 (12) |
Fe—O6 | 2.140 (12) | K—O4iv | 2.946 (15) |
Fe—O6i | 2.140 (12) | K—O5 | 3.121 (12) |
Fe—O7 | 2.081 (12) | K—O6vi | 2.978 (13) |
Fe—O7i | 2.081 (12) | S—O1 | 1.493 (13) |
K—O1ii | 2.731 (13) | S—O2 | 1.496 (15) |
K—O2iii | 2.942 (13) | S—O3 | 1.482 (16) |
K—O2iv | 2.890 (15) | S—O4 | 1.464 (13) |
| | | |
O5—Fe—O5i | 180.0 | O6—Fe—O7i | 90.9 (4) |
O5—Fe—O6 | 90.2 (4) | O6i—Fe—O7 | 90.9 (5) |
O5—Fe—O6i | 89.8 (4) | O6i—Fe—O7i | 89.1 (5) |
O5—Fe—O7 | 89.9 (4) | O7—Fe—O7i | 180.0 |
O5—Fe—O7i | 90.1 (4) | O1—S—O2 | 108.6 (7) |
O5i—Fe—O6 | 89.8 (4) | O1—S—O3 | 108.4 (6) |
O5i—Fe—O6i | 90.2 (4) | O1—S—O4 | 107.6 (6) |
O5i—Fe—O7 | 90.1 (4) | O2—S—O3 | 112.9 (8) |
O6i—Fe—O7i | 89.9 (4) | O2—S—O4 | 108.9 (6) |
O6—Fe—O6i | 180.0 | O3—S—O4 | 110.5 (7) |
O6—Fe—O7 | 89.1 (4) | | |
Symmetry codes: (i) −x, −y, −z; (ii) −x+1/2, y+1/2, −z; (iii) x, y, z+1; (iv) x−1/2, −y+1/2, z+1; (v) x−1/2, −y+1/2, z; (vi) x+1/2, −y+1/2, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H11···O3 | 0.98 | 1.82 | 2.73 (2) | 152 |
O5—H12···O1iii | 0.96 | 1.86 | 2.78 (2) | 162 |
O6—H21···O3v | 0.95 | 1.98 | 2.79 (2) | 142 |
O6—H22···O4vii | 0.96 | 1.92 | 2.70 (1) | 136 |
O7—H31···O2v | 0.97 | 1.85 | 2.64 (1) | 137 |
O7—H32···O1 | 0.98 | 1.86 | 2.70 (1) | 142 |
Symmetry codes: (iii) x, y, z+1; (v) x−1/2, −y+1/2, z; (vii) x−1, y, z. |