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The crystal structure of the new iron(III) arsenate, viz. tricaesium diiron(III) tris(arsenate), Cs3Fe2(AsO4)3, is built up from corner-sharing AsO4 tetrahedra and FeO5 trigonal bipyramids forming a three-dimensional open framework, which contains two channels running along the c axis where the Cs+ cations are located. This compound is a rare example of an oxide possessing Fe exclusively in trigonal-bipyramidal coordination.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (Fe-O) = 0.004 Å
- R factor = 0.024
- wR factor = 0.070
- Data-to-parameter ratio = 15.4
checkCIF/PLATON results
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PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
PLAT301_ALERT_3_C Main Residue Disorder ......................... 20.00 Perc.
0 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
2 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
1 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
1 ALERT type 3 Indicator that the structure quality may be low
0 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97.
tricesium diiron(III) tris(arsenate)
top
Crystal data top
Cs3Fe2(AsO4)3 | F(000) = 1648 |
Mr = 927.19 | Dx = 4.422 Mg m−3 |
Orthorhombic, Cmcm | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2c 2 | Cell parameters from 25 reflections |
a = 18.893 (4) Å | θ = 10–14° |
b = 11.214 (3) Å | µ = 16.94 mm−1 |
c = 6.573 (1) Å | T = 298 K |
V = 1392.6 (5) Å3 | Parallelepiped, yellow |
Z = 4 | 0.22 × 0.11 × 0.11 mm |
Data collection top
Enraf–Nonius CAD-4 diffractometer | 982 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.017 |
Graphite monochromator | θmax = 30.0°, θmin = 2.1° |
ω/2θ scans | h = −2→26 |
Absorption correction: ψ scan (North et al., 1968) | k = 0→15 |
Tmin = 0.122, Tmax = 0.161 | l = 0→9 |
1249 measured reflections | 2 standard reflections every 120 min |
1127 independent reflections | |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.024 | w = 1/[σ2(Fo2) + (0.0269P)2 + 8.8431P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.070 | (Δ/σ)max < 0.001 |
S = 1.25 | Δρmax = 1.22 e Å−3 |
1127 reflections | Δρmin = −0.75 e Å−3 |
73 parameters | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.00270 (11) |
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 | Occ. (<1) |
Cs1 | 0.0000 | 0.89581 (5) | −0.2500 | 0.02376 (16) | |
Cs2 | −0.11232 (2) | 0.58728 (4) | −0.2500 | 0.02574 (15) | |
Fe | 0.16745 (4) | 0.83319 (7) | 0.2500 | 0.01007 (18) | |
As1 | −0.21392 (3) | 0.88162 (5) | −0.2500 | 0.00964 (15) | |
As2 | 0.0000 | 0.74223 (8) | 0.2500 | 0.01268 (19) | |
O1 | −0.2289 (2) | 0.0297 (4) | −0.2500 | 0.0211 (10) | |
O2 | −0.2959 (3) | 0.8256 (5) | −0.2051 (8) | 0.0181 (17) | 0.50 |
O3 | −0.1774 (5) | 0.8210 (10) | −0.0414 (17) | 0.0189 (18) | 0.50 |
O3' | −0.1561 (5) | 0.8479 (9) | −0.0639 (16) | 0.0163 (17) | 0.50 |
O4 | 0.0000 | 0.6622 (5) | 0.0384 (8) | 0.0321 (12) | |
O5 | 0.0678 (2) | 0.8438 (4) | 0.2500 | 0.0214 (9) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cs1 | 0.0274 (3) | 0.0186 (3) | 0.0252 (3) | 0.000 | 0.000 | 0.000 |
Cs2 | 0.0201 (2) | 0.0268 (2) | 0.0303 (3) | −0.00530 (15) | 0.000 | 0.000 |
Fe | 0.0065 (3) | 0.0094 (4) | 0.0143 (4) | 0.0000 (3) | 0.000 | 0.000 |
As1 | 0.0105 (2) | 0.0101 (3) | 0.0084 (3) | −0.00099 (19) | 0.000 | 0.000 |
As2 | 0.0088 (3) | 0.0155 (4) | 0.0138 (4) | 0.000 | 0.000 | 0.000 |
O1 | 0.0146 (19) | 0.0072 (18) | 0.042 (3) | −0.0034 (15) | 0.000 | 0.000 |
O2 | 0.018 (2) | 0.013 (2) | 0.023 (5) | −0.0044 (19) | 0.005 (2) | −0.005 (2) |
O3 | 0.020 (5) | 0.024 (5) | 0.013 (4) | 0.003 (3) | 0.001 (4) | 0.003 (3) |
O3' | 0.015 (4) | 0.027 (5) | 0.007 (3) | 0.007 (3) | −0.001 (3) | 0.003 (3) |
O4 | 0.031 (2) | 0.036 (3) | 0.029 (3) | 0.000 | 0.000 | −0.019 (2) |
O5 | 0.0077 (17) | 0.025 (2) | 0.031 (3) | 0.0018 (17) | 0.000 | 0.000 |
Geometric parameters (Å, º) top
Cs1—O5i | 3.189 (5) | Cs2—O2xi | 3.593 (6) |
Cs1—O5ii | 3.189 (5) | Cs2—O2xii | 3.593 (6) |
Cs1—O4iii | 3.234 (6) | Cs2—O4xiii | 3.777 (5) |
Cs1—O4 | 3.234 (6) | Fe—O5 | 1.886 (4) |
Cs1—O3'iv | 3.237 (8) | Fe—O1xiv | 1.926 (4) |
Cs1—O3'v | 3.237 (8) | Fe—O3xv | 1.929 (12) |
Cs1—O3' | 3.237 (8) | Fe—O3iv | 1.929 (12) |
Cs1—O3'iii | 3.237 (8) | Fe—O2xvi | 1.933 (5) |
Cs1—O5vi | 3.5756 (17) | Fe—O3'iv | 2.081 (10) |
Cs1—O5 | 3.5756 (17) | Fe—O3'xv | 2.081 (10) |
Cs1—O5vii | 3.5756 (17) | As1—O3iii | 1.679 (11) |
Cs1—O5iv | 3.5756 (17) | As1—O3 | 1.679 (11) |
Cs2—O4 | 2.967 (4) | As1—O3'iii | 1.684 (10) |
Cs2—O4iii | 2.967 (4) | As1—O3' | 1.684 (10) |
Cs2—O1viii | 3.069 (4) | As1—O1xvii | 1.685 (4) |
Cs2—O3 | 3.203 (12) | As1—O2 | 1.698 (6) |
Cs2—O3iii | 3.203 (12) | As2—O4xviii | 1.655 (5) |
Cs2—O3' | 3.275 (11) | As2—O4 | 1.655 (5) |
Cs2—O3'iii | 3.275 (11) | As2—O5 | 1.715 (4) |
Cs2—O2ix | 3.421 (6) | As2—O5iv | 1.715 (4) |
Cs2—O2x | 3.421 (6) | | |
| | | |
O5—Fe—O1xiv | 123.4 (2) | O3iii—As1—O3 | 109.5 (8) |
O5—Fe—O3xv | 95.8 (3) | O3—As1—O3'iii | 103.6 (3) |
O1xiv—Fe—O3xv | 89.9 (3) | O3iii—As1—O3' | 103.6 (3) |
O5—Fe—O3iv | 95.8 (3) | O3'iii—As1—O3' | 93.2 (6) |
O1xiv—Fe—O3iv | 89.9 (3) | O3iii—As1—O1xvii | 117.9 (4) |
O3xv—Fe—O3iv | 166.2 (5) | O3—As1—O1xvii | 117.9 (4) |
O5—Fe—O2xvi | 114.5 (2) | O3'iii—As1—O1xvii | 109.3 (4) |
O1xiv—Fe—O2xvi | 121.3 (2) | O3'—As1—O1xvii | 109.3 (4) |
O3xv—Fe—O2xvi | 93.0 (3) | O3iii—As1—O2 | 111.6 (3) |
O3iv—Fe—O2xvi | 75.4 (3) | O3—As1—O2 | 94.8 (3) |
O5—Fe—O2xix | 114.5 (2) | O3'iii—As1—O2 | 129.5 (3) |
O1xiv—Fe—O2xix | 121.3 (2) | O3'—As1—O2 | 112.5 (3) |
O3xv—Fe—O2xix | 75.4 (3) | O1xvii—As1—O2 | 102.2 (2) |
O3iv—Fe—O2xix | 93.0 (3) | O3iii—As1—O2iii | 94.8 (3) |
O5—Fe—O3'iv | 83.8 (2) | O3—As1—O2iii | 111.6 (3) |
O1xiv—Fe—O3'iv | 89.9 (3) | O3'iii—As1—O2iii | 112.5 (3) |
O3xv—Fe—O3'iv | 179.4 (4) | O3'—As1—O2iii | 129.5 (3) |
O2xvi—Fe—O3'iv | 87.6 (3) | O1xvii—As1—O2iii | 102.2 (2) |
O2xix—Fe—O3'iv | 105.2 (3) | O4xviii—As2—O4 | 114.3 (4) |
O5—Fe—O3'xv | 83.8 (2) | O4xviii—As2—O5 | 111.10 (14) |
O1xiv—Fe—O3'xv | 89.9 (3) | O4—As2—O5 | 111.10 (14) |
O3iv—Fe—O3'xv | 179.4 (4) | O4xviii—As2—O5iv | 111.10 (13) |
O2xvi—Fe—O3'xv | 105.2 (3) | O4—As2—O5iv | 111.10 (13) |
O2xix—Fe—O3'xv | 87.6 (3) | O5—As2—O5iv | 96.8 (3) |
O3'iv—Fe—O3'xv | 165.0 (5) | | |
Symmetry codes: (i) x, −y+2, −z; (ii) −x, −y+2, −z; (iii) x, y, −z−1/2; (iv) −x, y, z; (v) −x, y, −z−1/2; (vi) −x, y, z−1; (vii) x, y, z−1; (viii) −x−1/2, y+1/2, z; (ix) −x−1/2, y−1/2, −z−1/2; (x) −x−1/2, y−1/2, z; (xi) −x−1/2, −y+3/2, z−1/2; (xii) −x−1/2, −y+3/2, −z; (xiii) −x, −y+1, z−1/2; (xiv) −x, −y+1, −z; (xv) −x, y, −z+1/2; (xvi) x+1/2, −y+3/2, −z; (xvii) x, y+1, z; (xviii) x, y, −z+1/2; (xix) x+1/2, −y+3/2, z+1/2. |
Indice de distorsion des polyèdres de coordination de Fe et As topPolyèdre | IDd | IDa | IDo |
FeO5 | 0.0046 | 0.1333 | 0.0813 |
As1O4 | 0.0040 | 0.01462 | 0.0319 |
As2O4 | 0.0175 | 0.0380 | 0.0219 |
Notes: IDd = [Σi = 1n1(|di–dm|)/n1dm],
IDa = [Σi = 1n2(|ai–am|)/n2am] et
IDo = [Σi = 1n2(|oi–om|)/n2om], avec
d = distance Fe/As—O, a = angle O—Fe/As—O, o = distance O—O,
m = valeur moyenne, et n1 et n2 valent 4 et 6 pour le tétraèdre et
5 et 9 pour le polyèdre bipyramide à base triangulaire. |
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