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The complex phosphate tricaesium calcium iron bis(diphosphate), Cs3CaFe(P2O7)2, has been prepared by the flux method. Isolated [FeO5] and [CaO6] polyhedra are linked by two types of P2O7 groups into a three-dimensional framework. The latter is penetrated by hexagonal channels along the a axis where three Cs atoms are located. Calculations of caesium Voronoi-Dirichlet polyhedra give coordination schemes for the three Cs atoms as [8 + 3], [9 + 1] and [9 + 4]. The structure includes features of both two- and three-dimensional frameworks of caesium double pyrophosphates.
Supporting information
The triple pyrophosphate (I) was obtained from a high-temperature solution in
the system Cs2O–P2O5–Fe2O3–CaO. H3PO4 (0.3 ml contained 0.392 g H3PO4) was added dropwise to a grounded mixture of CsPO3 (2.000 g),
Fe2O3 (0.215 g), CaCO3 (0.268 g). The composition obtained corresponding
to a molar ratio Cs/P = 0.7, Fe/P = 1/5, Ca/P = 0.2 was slowly heated in a
platinum crucible up to 1223 K and kept at this temperature for 1 h.
Crystallization at 1023 K was performed for 5 h. The resulting melt contained
colourless prismatic crystals of (I) which were leached out with deionized
water to dissolve the superfluous flux.
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).
tricaesium calcium iron bis(diphosphate)
top
Crystal data top
Cs3CaFe(P2O7)2 | Z = 4 |
Mr = 842.54 | F(000) = 1532 |
Orthorhombic, P212121 | Dx = 3.545 Mg m−3 |
Hall symbol: P2ac2ab | Mo Kα radiation, λ = 0.71073 Å |
a = 9.3001 (4) Å | µ = 8.57 mm−1 |
b = 11.2399 (5) Å | T = 293 K |
c = 15.1010 (6) Å | 0.10 × 0.03 × 0.01 mm |
V = 1578.54 (12) Å3 | |
Data collection top
Radiation source: fine-focus sealed tube | Rint = 0.062 |
Graphite monochromator | θmax = 30.0°, θmin = 2.7° |
11400 measured reflections | h = −13→7 |
4578 independent reflections | k = −15→15 |
3632 reflections with I > 2σ(I) | l = −18→21 |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0283P)2 + 0.0723P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.036 | (Δ/σ)max < 0.001 |
wR(F2) = 0.069 | Δρmax = 1.24 e Å−3 |
S = 0.97 | Δρmin = −1.64 e Å−3 |
4578 reflections | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
209 parameters | Extinction coefficient: 0.0046 (2) |
0 restraints | Absolute structure: Flack (1983), 1966 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.01 (2) |
Crystal data top
Cs3CaFe(P2O7)2 | V = 1578.54 (12) Å3 |
Mr = 842.54 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 9.3001 (4) Å | µ = 8.57 mm−1 |
b = 11.2399 (5) Å | T = 293 K |
c = 15.1010 (6) Å | 0.10 × 0.03 × 0.01 mm |
Data collection top
11400 measured reflections | 3632 reflections with I > 2σ(I) |
4578 independent reflections | Rint = 0.062 |
Refinement top
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.069 | Δρmax = 1.24 e Å−3 |
S = 0.97 | Δρmin = −1.64 e Å−3 |
4578 reflections | Absolute structure: Flack (1983), 1966 Friedel pairs |
209 parameters | Absolute structure parameter: −0.01 (2) |
Special details top
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell esds are taken
into account individually in the estimation of esds in distances, angles
and torsion angles; correlations between esds in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell esds is used for estimating esds 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 > 2sigma(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 | |
O1 | 0.4282 (5) | 0.2320 (5) | 0.0313 (4) | 0.0246 (12) | |
O2 | 0.5297 (6) | 0.0036 (4) | −0.2228 (3) | 0.0230 (11) | |
O3 | 0.5821 (6) | 0.5308 (6) | 0.2700 (3) | 0.0299 (14) | |
O4 | 0.7117 (5) | 0.5868 (4) | 0.1288 (3) | 0.0223 (11) | |
O5 | 0.5002 (5) | 0.1869 (4) | −0.1250 (3) | 0.0175 (10) | |
O6 | 0.5560 (6) | 0.2124 (5) | −0.2824 (3) | 0.0264 (12) | |
O7 | 0.4511 (4) | 0.6336 (4) | 0.1490 (3) | 0.0133 (9) | |
O8 | 0.4710 (5) | 0.0191 (4) | −0.0126 (3) | 0.0166 (10) | |
O9 | 0.5315 (5) | 0.4205 (4) | 0.1303 (4) | 0.0239 (12) | |
O11 | 0.2440 (5) | 0.3707 (5) | 0.1814 (3) | 0.0210 (11) | |
O10 | 0.6776 (5) | 0.1649 (5) | −0.0007 (3) | 0.0200 (11) | |
O12 | 0.2038 (5) | 0.6809 (5) | 0.0998 (3) | 0.0215 (11) | |
O13 | 0.4137 (5) | 0.7433 (5) | 0.0040 (3) | 0.0223 (12) | |
O14 | 0.3494 (5) | 0.5282 (4) | 0.0149 (3) | 0.0206 (11) | |
P1 | 0.51962 (17) | 0.14486 (16) | −0.02141 (11) | 0.0115 (4) | |
P2 | 0.58407 (17) | 0.12858 (16) | −0.20814 (11) | 0.0124 (3) | |
P3 | 0.58060 (17) | 0.53843 (17) | 0.17165 (11) | 0.0120 (4) | |
P4 | 0.34851 (17) | 0.64994 (15) | 0.06195 (11) | 0.0100 (3) | |
Ca1 | 0.45553 (12) | −0.13533 (11) | −0.11675 (8) | 0.0071 (2) | |
Fe1 | 0.34997 (9) | 0.37596 (9) | 0.07286 (6) | 0.01095 (19) | |
Cs1 | 0.62755 (4) | −0.12957 (4) | 0.12997 (3) | 0.01818 (11) | |
Cs2 | 0.72190 (5) | 0.21268 (5) | 0.19591 (3) | 0.02610 (13) | |
Cs3 | 0.17569 (5) | −0.01048 (6) | 0.08968 (4) | 0.03815 (16) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
P1 | 0.0084 (7) | 0.0116 (9) | 0.0146 (8) | 0.0018 (6) | 0.0013 (6) | −0.0030 (7) |
O8 | 0.026 (3) | 0.008 (2) | 0.016 (2) | −0.001 (2) | 0.003 (2) | −0.003 (2) |
O10 | 0.010 (2) | 0.028 (3) | 0.023 (3) | 0.003 (2) | −0.002 (2) | −0.009 (2) |
O1 | 0.017 (3) | 0.021 (3) | 0.036 (3) | 0.007 (2) | 0.005 (2) | −0.006 (3) |
O5 | 0.020 (2) | 0.017 (3) | 0.015 (2) | 0.0110 (19) | 0.001 (2) | 0.002 (2) |
P2 | 0.0122 (7) | 0.0140 (8) | 0.0109 (8) | −0.0010 (7) | −0.0015 (6) | 0.0048 (8) |
O4 | 0.011 (2) | 0.026 (3) | 0.030 (3) | −0.0038 (19) | 0.005 (2) | 0.001 (2) |
O3 | 0.026 (3) | 0.053 (4) | 0.011 (2) | −0.004 (3) | −0.006 (2) | 0.011 (3) |
O9 | 0.011 (2) | 0.016 (3) | 0.045 (3) | 0.0053 (19) | −0.010 (2) | −0.005 (3) |
O7 | 0.012 (2) | 0.014 (2) | 0.014 (2) | 0.003 (2) | −0.0050 (17) | 0.000 (2) |
P3 | 0.0074 (7) | 0.0131 (9) | 0.0156 (9) | −0.0008 (6) | −0.0023 (6) | 0.0042 (7) |
O6 | 0.034 (3) | 0.027 (3) | 0.019 (3) | 0.005 (2) | −0.003 (2) | 0.016 (2) |
O2 | 0.036 (3) | 0.017 (3) | 0.016 (2) | −0.008 (2) | 0.000 (2) | 0.004 (2) |
O11 | 0.012 (2) | 0.037 (3) | 0.014 (2) | 0.001 (2) | 0.0026 (19) | 0.001 (2) |
P4 | 0.0080 (8) | 0.0103 (9) | 0.0117 (8) | −0.0015 (6) | −0.0018 (6) | 0.0028 (7) |
O13 | 0.024 (3) | 0.022 (3) | 0.021 (3) | −0.009 (2) | −0.002 (2) | 0.010 (2) |
O12 | 0.006 (2) | 0.035 (3) | 0.024 (3) | 0.0017 (19) | 0.0003 (19) | 0.001 (2) |
O14 | 0.030 (3) | 0.013 (3) | 0.019 (3) | −0.003 (2) | −0.010 (2) | 0.000 (2) |
Ca1 | 0.0073 (5) | 0.0070 (6) | 0.0070 (6) | 0.0000 (5) | 0.0004 (4) | −0.0010 (5) |
Fe1 | 0.0088 (4) | 0.0097 (5) | 0.0144 (4) | 0.0004 (4) | 0.0012 (3) | −0.0025 (4) |
Cs1 | 0.0175 (2) | 0.0198 (2) | 0.0172 (2) | −0.00091 (18) | −0.00198 (18) | −0.0005 (2) |
Cs2 | 0.0228 (2) | 0.0385 (3) | 0.0171 (2) | −0.0069 (2) | 0.0014 (2) | 0.0032 (2) |
Cs3 | 0.0235 (2) | 0.0640 (4) | 0.0269 (3) | 0.0006 (2) | −0.0019 (2) | 0.0035 (3) |
Geometric parameters (Å, º) top
Ca1—O6i | 2.294 (5) | Cs2—O3 | 3.964 (5) |
Ca1—O13ii | 2.310 (5) | Cs3—O3v | 3.127 (5) |
Ca1—O4iii | 2.339 (4) | Cs3—O2vii | 3.416 (5) |
Ca1—O2 | 2.341 (5) | Cs3—O4iii | 3.426 (5) |
Ca1—O8 | 2.346 (5) | Cs3—O14iii | 3.427 (5) |
Ca1—O12iv | 2.379 (5) | Cs3—O12ii | 3.482 (5) |
Fe1—O1 | 1.882 (5) | Cs3—O6vii | 3.678 (6) |
Fe1—O11 | 1.914 (4) | Cs3—O9iii | 3.723 (6) |
Fe1—O14 | 1.923 (5) | Cs3—O13ii | 3.772 (6) |
Fe1—O10iii | 1.992 (5) | Cs3—O8 | 3.168 (5) |
Fe1—O9 | 1.963 (5) | Cs3—O1 | 3.704 (6) |
Cs1—O3v | 3.054 (5) | Cs3—O13iii | 3.845 (5) |
Cs1—O11v | 3.088 (4) | Cs3—O5iii | 4.021 (5) |
Cs1—O8 | 3.090 (5) | Cs3—O10iii | 4.113 (5) |
Cs1—O13ii | 3.100 (5) | P1—O8 | 1.491 (5) |
Cs1—O7ii | 3.141 (5) | P1—O10 | 1.519 (5) |
Cs1—O14iv | 3.215 (5) | P1—O1 | 1.522 (5) |
Cs1—O4ii | 3.282 (5) | P1—O5 | 1.644 (5) |
Cs1—O6vi | 3.359 (5) | P2—O6 | 1.487 (5) |
Cs1—O13iv | 3.579 (5) | P2—O2 | 1.509 (5) |
Cs1—O12iv | 3.588 (5) | P2—O11iv | 1.541 (4) |
Cs1—O10 | 3.879 (5) | P2—O5 | 1.616 (5) |
Cs2—O7v | 2.977 (4) | P3—O4 | 1.484 (5) |
Cs2—O5iv | 3.020 (4) | P3—O3 | 1.488 (5) |
Cs2—O10 | 3.045 (5) | P3—O9 | 1.535 (5) |
Cs2—O9 | 3.094 (5) | P3—O7 | 1.646 (5) |
Cs2—O12v | 3.182 (5) | P4—O13 | 1.495 (5) |
Cs2—O6iv | 3.474 (5) | P4—O12 | 1.503 (5) |
Cs2—O3v | 3.527 (6) | P4—O14 | 1.542 (5) |
Cs2—O2vi | 3.571 (5) | P4—O7 | 1.635 (4) |
Cs2—O1 | 3.699 (5) | | |
| | | |
O8—P1—O10 | 114.6 (3) | O8—Cs1—O12iv | 60.41 (12) |
O8—P1—O1 | 113.2 (3) | O13ii—Cs1—O12iv | 57.29 (12) |
O10—P1—O1 | 109.7 (3) | O7ii—Cs1—O12iv | 93.18 (11) |
O8—P1—O5 | 108.9 (3) | O14iv—Cs1—O12iv | 43.31 (11) |
O10—P1—O5 | 105.0 (3) | O4ii—Cs1—O12iv | 77.98 (13) |
O1—P1—O5 | 104.6 (3) | O6vi—Cs1—O12iv | 99.39 (11) |
P2—O5—P1 | 124.7 (3) | O13iv—Cs1—O12iv | 41.32 (11) |
O6—P2—O2 | 114.8 (3) | O7v—Cs2—O5iv | 148.61 (12) |
O6—P2—O11iv | 111.3 (3) | O7v—Cs2—O10 | 129.88 (12) |
O2—P2—O11iv | 111.5 (3) | O5iv—Cs2—O10 | 80.57 (13) |
O6—P2—O5 | 104.1 (3) | O7v—Cs2—O9 | 99.68 (13) |
O2—P2—O5 | 109.2 (3) | O5iv—Cs2—O9 | 95.43 (13) |
O11iv—P2—O5 | 105.1 (3) | O10—Cs2—O9 | 75.13 (14) |
P4—O7—P3 | 131.9 (3) | O7v—Cs2—O12v | 47.23 (11) |
O4—P3—O3 | 116.7 (3) | O5iv—Cs2—O12v | 101.52 (12) |
O4—P3—O9 | 112.6 (3) | O10—Cs2—O12v | 162.75 (13) |
O3—P3—O9 | 111.0 (3) | O9—Cs2—O12v | 121.30 (14) |
O4—P3—O7 | 105.8 (3) | O7v—Cs2—O6iv | 105.07 (11) |
O3—P3—O7 | 104.6 (3) | O5iv—Cs2—O6iv | 43.62 (12) |
O9—P3—O7 | 105.0 (2) | O10—Cs2—O6iv | 122.02 (12) |
O13—P4—O12 | 115.0 (3) | O9—Cs2—O6iv | 116.69 (13) |
O13—P4—O14 | 110.6 (3) | O12v—Cs2—O6iv | 57.90 (11) |
O12—P4—O14 | 112.7 (3) | O7v—Cs2—O3v | 43.86 (11) |
O13—P4—O7 | 108.2 (3) | O5iv—Cs2—O3v | 162.84 (12) |
O12—P4—O7 | 104.1 (3) | O10—Cs2—O3v | 86.08 (12) |
O14—P4—O7 | 105.5 (3) | O9—Cs2—O3v | 91.47 (13) |
O6i—Ca1—O13ii | 94.4 (2) | O12v—Cs2—O3v | 88.14 (11) |
O6i—Ca1—O4iii | 94.41 (18) | O6iv—Cs2—O3v | 143.39 (11) |
O13ii—Ca1—O4iii | 92.07 (19) | O7v—Cs2—O2vi | 82.87 (11) |
O6i—Ca1—O2 | 93.28 (19) | O5iv—Cs2—O2vi | 79.75 (12) |
O13ii—Ca1—O2 | 169.58 (19) | O10—Cs2—O2vi | 107.62 (12) |
O4iii—Ca1—O2 | 94.40 (18) | O9—Cs2—O2vi | 173.83 (12) |
O6i—Ca1—O8 | 179.01 (19) | O12v—Cs2—O2vi | 56.62 (12) |
O13ii—Ca1—O8 | 85.28 (18) | O6iv—Cs2—O2vi | 57.14 (12) |
O4iii—Ca1—O8 | 86.53 (18) | O3v—Cs2—O2vi | 94.22 (12) |
O2—Ca1—O8 | 86.97 (17) | O7v—Cs2—O1 | 98.45 (11) |
O6i—Ca1—O12iv | 87.48 (19) | O5iv—Cs2—O1 | 111.89 (12) |
O13ii—Ca1—O12iv | 87.21 (18) | O10—Cs2—O1 | 41.87 (12) |
O4iii—Ca1—O12iv | 178.02 (19) | O9—Cs2—O1 | 47.00 (13) |
O2—Ca1—O12iv | 86.05 (18) | O12v—Cs2—O1 | 144.92 (12) |
O8—Ca1—O12iv | 91.58 (17) | O6iv—Cs2—O1 | 153.99 (12) |
O1—Fe1—O11 | 117.2 (2) | O3v—Cs2—O1 | 62.62 (12) |
O1—Fe1—O14 | 127.9 (2) | O2vi—Cs2—O1 | 138.45 (12) |
O11—Fe1—O14 | 114.6 (2) | O3v—Cs3—O8 | 71.95 (13) |
O1—Fe1—O9 | 91.9 (2) | O3v—Cs3—O2vii | 80.68 (13) |
O11—Fe1—O9 | 94.1 (2) | O8—Cs3—O2vii | 152.41 (12) |
O14—Fe1—O9 | 88.7 (2) | O3v—Cs3—O4iii | 128.25 (12) |
O1—Fe1—O10iii | 86.0 (2) | O8—Cs3—O4iii | 58.12 (11) |
O11—Fe1—O10iii | 92.70 (19) | O2vii—Cs3—O4iii | 149.16 (11) |
O14—Fe1—O10iii | 87.4 (2) | O3v—Cs3—O14iii | 163.50 (12) |
O9—Fe1—O10iii | 173.1 (2) | O8—Cs3—O14iii | 123.32 (12) |
O3v—Cs1—O11v | 77.89 (13) | O2vii—Cs3—O14iii | 83.56 (12) |
O3v—Cs1—O8 | 74.02 (13) | O4iii—Cs3—O14iii | 68.19 (11) |
O11v—Cs1—O8 | 145.52 (13) | O3v—Cs3—O12ii | 93.66 (14) |
O3v—Cs1—O13ii | 99.54 (14) | O8—Cs3—O12ii | 93.47 (11) |
O11v—Cs1—O13ii | 144.51 (14) | O2vii—Cs3—O12ii | 91.61 (12) |
O8—Cs1—O13ii | 61.27 (13) | O4iii—Cs3—O12ii | 77.61 (12) |
O3v—Cs1—O7ii | 96.98 (14) | O14iii—Cs3—O12ii | 91.65 (11) |
O11v—Cs1—O7ii | 96.81 (13) | O3v—Cs3—O6vii | 99.07 (14) |
O8—Cs1—O7ii | 106.01 (11) | O8—Cs3—O6vii | 145.95 (12) |
O13ii—Cs1—O7ii | 47.97 (11) | O2vii—Cs3—O6vii | 41.49 (11) |
O3v—Cs1—O14iv | 122.47 (14) | O4iii—Cs3—O6vii | 114.13 (11) |
O11v—Cs1—O14iv | 112.26 (12) | O14iii—Cs3—O6vii | 71.78 (12) |
O8—Cs1—O14iv | 68.70 (13) | O12ii—Cs3—O6vii | 53.57 (11) |
O13ii—Cs1—O14iv | 99.06 (13) | O3v—Cs3—O1 | 66.12 (14) |
O7ii—Cs1—O14iv | 134.25 (12) | O8—Cs3—O1 | 42.04 (11) |
O3v—Cs1—O4ii | 136.71 (14) | O2vii—Cs3—O1 | 122.35 (12) |
O11v—Cs1—O4ii | 85.04 (14) | O4iii—Cs3—O1 | 83.87 (12) |
O8—Cs1—O4ii | 129.34 (13) | O14iii—Cs3—O1 | 119.66 (12) |
O13ii—Cs1—O4ii | 72.69 (13) | O12ii—Cs3—O1 | 134.09 (10) |
O7ii—Cs1—O4ii | 45.72 (11) | O6vii—Cs3—O1 | 161.89 (11) |
O14iv—Cs1—O4ii | 100.80 (12) | O3v—Cs3—O9iii | 145.47 (13) |
O3v—Cs1—O6vi | 121.87 (13) | O8—Cs3—O9iii | 81.30 (11) |
O11v—Cs1—O6vi | 45.41 (12) | O2vii—Cs3—O9iii | 122.15 (11) |
O8—Cs1—O6vi | 146.87 (13) | O4iii—Cs3—O9iii | 40.87 (11) |
O13ii—Cs1—O6vi | 132.54 (14) | O14iii—Cs3—O9iii | 44.41 (10) |
O7ii—Cs1—O6vi | 100.77 (12) | O12ii—Cs3—O9iii | 109.69 (11) |
O14iv—Cs1—O6vi | 78.69 (13) | O6vii—Cs3—O9iii | 115.18 (11) |
O4ii—Cs1—O6vi | 61.57 (13) | O1—Cs3—O9iii | 79.41 (11) |
O3v—Cs1—O13iv | 164.76 (15) | O3v—Cs3—O13ii | 85.31 (13) |
O11v—Cs1—O13iv | 103.54 (12) | O8—Cs3—O13ii | 53.20 (11) |
O8—Cs1—O13iv | 98.61 (11) | O2vii—Cs3—O13ii | 128.96 (12) |
O13ii—Cs1—O13iv | 88.02 (2) | O4iii—Cs3—O13ii | 55.15 (11) |
O7ii—Cs1—O13iv | 97.89 (12) | O14iii—Cs3—O13ii | 108.61 (11) |
O14iv—Cs1—O13iv | 42.69 (12) | O12ii—Cs3—O13ii | 40.55 (11) |
O4ii—Cs1—O13iv | 58.18 (12) | O6vii—Cs3—O13ii | 94.09 (11) |
O6vi—Cs1—O13iv | 58.14 (12) | O1—Cs3—O13ii | 94.94 (11) |
O3v—Cs1—O12iv | 134.36 (12) | O9iii—Cs3—O13ii | 96.01 (11) |
O11v—Cs1—O12iv | 144.63 (10) | | |
Symmetry codes: (i) −x+1, y−1/2, −z−1/2; (ii) x, y−1, z; (iii) x−1/2, −y+1/2, −z; (iv) x+1/2, −y+1/2, −z; (v) −x+1, y−1/2, −z+1/2; (vi) −x+3/2, −y, z+1/2; (vii) −x+1/2, −y, z+1/2. |
Experimental details
Crystal data |
Chemical formula | Cs3CaFe(P2O7)2 |
Mr | 842.54 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 293 |
a, b, c (Å) | 9.3001 (4), 11.2399 (5), 15.1010 (6) |
V (Å3) | 1578.54 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 8.57 |
Crystal size (mm) | 0.10 × 0.03 × 0.01 |
|
Data collection |
Diffractometer | ? |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11400, 4578, 3632 |
Rint | 0.062 |
(sin θ/λ)max (Å−1) | 0.703 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.069, 0.97 |
No. of reflections | 4578 |
No. of parameters | 209 |
Δρmax, Δρmin (e Å−3) | 1.24, −1.64 |
Absolute structure | Flack (1983), 1966 Friedel pairs |
Absolute structure parameter | −0.01 (2) |
Selected geometric parameters (Å, º) topCa1—O6i | 2.294 (5) | Cs2—O3 | 3.964 (5) |
Ca1—O13ii | 2.310 (5) | Cs3—O3v | 3.127 (5) |
Ca1—O4iii | 2.339 (4) | Cs3—O2vii | 3.416 (5) |
Ca1—O2 | 2.341 (5) | Cs3—O4iii | 3.426 (5) |
Ca1—O8 | 2.346 (5) | Cs3—O14iii | 3.427 (5) |
Ca1—O12iv | 2.379 (5) | Cs3—O12ii | 3.482 (5) |
Fe1—O1 | 1.882 (5) | Cs3—O6vii | 3.678 (6) |
Fe1—O11 | 1.914 (4) | Cs3—O9iii | 3.723 (6) |
Fe1—O14 | 1.923 (5) | Cs3—O13ii | 3.772 (6) |
Fe1—O10iii | 1.992 (5) | Cs3—O8 | 3.168 (5) |
Fe1—O9 | 1.963 (5) | Cs3—O1 | 3.704 (6) |
Cs1—O3v | 3.054 (5) | Cs3—O13iii | 3.845 (5) |
Cs1—O11v | 3.088 (4) | Cs3—O5iii | 4.021 (5) |
Cs1—O8 | 3.090 (5) | Cs3—O10iii | 4.113 (5) |
Cs1—O13ii | 3.100 (5) | P1—O8 | 1.491 (5) |
Cs1—O7ii | 3.141 (5) | P1—O10 | 1.519 (5) |
Cs1—O14iv | 3.215 (5) | P1—O1 | 1.522 (5) |
Cs1—O4ii | 3.282 (5) | P1—O5 | 1.644 (5) |
Cs1—O6vi | 3.359 (5) | P2—O6 | 1.487 (5) |
Cs1—O13iv | 3.579 (5) | P2—O2 | 1.509 (5) |
Cs1—O12iv | 3.588 (5) | P2—O11iv | 1.541 (4) |
Cs1—O10 | 3.879 (5) | P2—O5 | 1.616 (5) |
Cs2—O7v | 2.977 (4) | P3—O4 | 1.484 (5) |
Cs2—O5iv | 3.020 (4) | P3—O3 | 1.488 (5) |
Cs2—O10 | 3.045 (5) | P3—O9 | 1.535 (5) |
Cs2—O9 | 3.094 (5) | P3—O7 | 1.646 (5) |
Cs2—O12v | 3.182 (5) | P4—O13 | 1.495 (5) |
Cs2—O6iv | 3.474 (5) | P4—O12 | 1.503 (5) |
Cs2—O3v | 3.527 (6) | P4—O14 | 1.542 (5) |
Cs2—O2vi | 3.571 (5) | P4—O7 | 1.635 (4) |
Cs2—O1 | 3.699 (5) | | |
| | | |
P2—O5—P1 | 124.7 (3) | P4—O7—P3 | 131.9 (3) |
Symmetry codes: (i) −x+1, y−1/2, −z−1/2; (ii) x, y−1, z; (iii) x−1/2, −y+1/2, −z; (iv) x+1/2, −y+1/2, −z; (v) −x+1, y−1/2, −z+1/2; (vi) −x+3/2, −y, z+1/2; (vii) −x+1/2, −y, z+1/2. |
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Double pyrophosphates of caesium and polyvalent metals have been widely investigated, for instance, Cs2MIIP2O7 (MII = Ca, Sr) (Zatovsky et al., 2008; Trunov et al.1991) and CsMIIIP2O7 (MIII = V, Cr, Fe, Mo, Yb) (Wang & Lii, 1989; Linde & Gorbunova, 1982; Millet & Mentzen, 1991; Lii & Haushalter, 1987; Jansen et al., 1991), as well as a set of oxypyrophosphates Cs2MIVOP2O7 (MIV = Ti, V) (Protas et al., 1991; Lii & Wang, 1989), CsMVOP2O7 (MV = Nb, Mo) (Nikolaev et al., 1982; Guesdon et al., 1994) and CsUO2P2O7 (Linde et al., 1981). However, there are no examples of compounds containing caesium with different polyvalent metals. Herein we report the structure of a new triple pyrophosphate, Cs3CaFe(P2O7)2, (I), prepared from a self-flux synthesis.
The structure of (I) is built up from isolated [CaO6] and [FeO5] polyhedra interlinked via two types of P2O7 groups (Fig. 1). Fe atoms form two types of six-membered rings [Fe(OP)2O] due to the chelating role of pyrophosphate. The values of these four Fe—O distances lie in the range of 1.912 (5)–1.993 (5) Å. Completeness of the [FeO5] polyhedra is achieved by an additional P2O7 group attached above the ring with a slightly shortened Fe—O distance of 1.882 (5) Å in a monodentate manner. The Ca atoms are in a quite distorted octahedron composed of one bidentate and four monodentate pyrophosphates. As a result, the main structural unit [CaFe(P2O7)2] is formed giving an anionic three-dimensional framework. The latter is penetrated by hexagonal channels along the direction [100], where three types of Cs atoms are located (Fig. 2).
Caesium polyhedra for double pyrophosphates are generally described with the cut-off distance Cs—O up to 3.6 Å. Taking into account this assumption for (I), the oxygen coordination of caesium can be exemplified as Cs1O10, Cs2O8, Cs3O6. In this crystal they are represented in open polyhedra. For more precise determination of the coordination numbers (CN) of Cs1–Cs3 the construction of Voronoi–Dirichlet polyhedra (VDP) was applied through the DIRICHLET program included in the TOPOS package (Blatov et al., 1995). The general considerations concerning the VDP calculations were applied as previously described (Blatov et al., 1998). All details connected with this procedure are given as supplementary materials and will not be discussed here. Analysis of the solid angle (Ω) distribution for each case revealed 11 Cs—O contacts of Cs1 and Cs2 up to 4.1 Å [R(Cs1—O)av = 3.876 and R(Cs2—O)av = 3.671 Å, respectively], neglecting those corresponding to Ω < 1.5% (Blatov et al., 1998). Thus, the coordination scheme for Cs1 and Cs2 is described as [8+3] and [9+1]: eight/nine contacts are in the range 2.978 (4)–3.574 (5) Å meaning `ion–covalent` bonds. The three/one are in the range 3.579 (5)–3.964 (5) Å corresponding to 1.5% < Ω < 5% and [it is worth] noticing that the solid angle [Ω = 1.57%, R(Cs2—O14) = 4.342 Å] for the longest contact is in the vicinity of the cut-off value. The same considerations are correct for Cs3 resulting in a [9+4] scheme at a cut-off distance of 4.113 Å.
The composition of (I) may be represented as Cs2CaP2O7×CsFeP2O7. In comparison, the structure of Cs2CaP2O7 (Zatovsky et al., 2008) also contains isolated [CaO]6 octahedra in layers organized into a three-dimensional framework by the P2O7 unit. Caesium resides in hexagonal [channel] tunnels between the above-mentioned layers. The second structure, CsFeP2O7 (Millet & Mentzen, 1991), differs significantly from (I) and is built up from isolated [FeO]6 linked into pairs by pyrophosphate bridges into ribbons. Because of the alternation in a chess order into a three-dimensional net, the channels with Cs atoms appear.
In the case of structure (I) the anionic sublattice [CaFe(P2O7)2]3- can be seen as containing zigzag layers (Fig. 3) attached to each other via one of the P2O7 groups. Aggregation of [MOn] (n = 5 or 6) with P2O7 into layers is common for a set of complex pyrophosphates, for example CsNaMnP2O7 (Huang & Hwu, 1998), Cs2TiOP2O7 (Protas et al., 1991), Cs2VOP2O7 (Lii & Wang, 1989), CsNbOP2O7 (Nikolaev et al., 1982) and Cs2UO2P2O7 (Linde et al., 1981). According to the structural data, these layers can be either flat or zigzag (Fig. 3) and separated from each other by sheets of alkaline metals. Consequently, the structure of (I) contains features of both layered and three-dimensional frameworks simultaneously.