Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270110001344/fn3041sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270110001344/fn3041Isup2.hkl |
The title compound was prepared from a reaction mixture of H3PO4 (4 mmol), FeO (5 mmol) and Al2O3 (5 mmol) in water (approximately 6 ml). The starting mixture was transferred and sealed into a 23 ml Teflon-lined stainless steel Parr autoclave under autogenous pressure, filled to approximately 25% volume capacity, and all reactants were stirred briefly before heating. The reaction mixture was heated at 343 K for 3 d to obtain (Fe0.81Al0.19)(H2PO4)3, followed by slow cooling to room temperature. The product was filtered off, washed with deionized water and dried in air. A needle single crystal of (Fe0.81Al0.19)(H2PO4)3 was selected under a polarizing microscope.
During refinement, the occupancy of the Fe site exhibited a significant deviation from full occupancy, indicating a substitution with Al; the final occupancies were constrained to sum to 1.0 and refined to 0.807 (7) and 0.193 (7), respectively, for Fe1 and Al1. The positions of all H atoms were located from a difference electron-density map and then refined with an O—H bond length restraint of 0.95 (5)Å and with Uiso(H) fixed at a value of 0.05 Å2.
Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); data reduction: MolEN (Fair, 1990); 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).
(Fe0.81Al0.19)(H2PO4)3 | F(000) = 682 |
Mr = 341.32 | Dx = 2.495 Mg m−3 |
Monoclinic, Cc | Melting point: Al0.19 Fe0.81 H6 O12 P3 K |
Hall symbol: C -2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 11.700 (1) Å | Cell parameters from 25 reflections |
b = 15.590 (1) Å | θ = 2.2–26.9° |
c = 5.030 (1) Å | µ = 1.98 mm−1 |
β = 98.00 (1)° | T = 293 K |
V = 908.6 (2) Å3 | Parallelepiped, grey |
Z = 4 | 0.15 × 0.15 × 0.1 mm |
Enraf–Nonius CAD-4 diffractometer | 1043 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.000 |
Graphite monochromator | θmax = 26.9°, θmin = 2.2° |
ω/2θ scans | h = −14→14 |
Absorption correction: ψ scan (North et al., 1968) | k = −19→0 |
Tmin = 0.703, Tmax = 0.754 | l = −6→0 |
1104 measured reflections | 2 standard reflections every 120 min |
1104 independent reflections | intensity decay: 0.4% |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.029 | w = 1/[σ2(Fo2) + (0.0495P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.074 | (Δ/σ)max = 0.001 |
S = 1.04 | Δρmax = 0.55 e Å−3 |
1104 reflections | Δρmin = −0.64 e Å−3 |
166 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
10 restraints | Extinction coefficient: 0.0129 (12) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.00 (3) |
(Fe0.81Al0.19)(H2PO4)3 | V = 908.6 (2) Å3 |
Mr = 341.32 | Z = 4 |
Monoclinic, Cc | Mo Kα radiation |
a = 11.700 (1) Å | µ = 1.98 mm−1 |
b = 15.590 (1) Å | T = 293 K |
c = 5.030 (1) Å | 0.15 × 0.15 × 0.1 mm |
β = 98.00 (1)° |
Enraf–Nonius CAD-4 diffractometer | 1043 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.000 |
Tmin = 0.703, Tmax = 0.754 | 2 standard reflections every 120 min |
1104 measured reflections | intensity decay: 0.4% |
1104 independent reflections |
R[F2 > 2σ(F2)] = 0.029 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.074 | Δρmax = 0.55 e Å−3 |
S = 1.04 | Δρmin = −0.64 e Å−3 |
1104 reflections | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
166 parameters | Absolute structure parameter: 0.00 (3) |
10 restraints |
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 > 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. A needle-shaped single crystal of (Fe0.81Al0.19)(H2PO4)3 with dimensions given in crystal data table was selected under a polarizing microscope. Diffraction data were collected at room temperature on an automated diffractometer using graphite-monochromated Mo Kα. Details of crystal data, intensity collection, and some features of the structure refinement are reported in crystal data table. Corrections for Lorentz and polarization effects were done and also for absorption with the empirical ψ scan method (North et al., 1968). The structures were solved by Patterson methods SHELXS97 (Sheldrick, 1997) in the Cc space group, which allowed to obtain the positions of Fe and phosphorus atoms. The refinement of the crystal structure was performed by full matrix least-squares based, on F2, using SHELXL97 program (Sheldrick,1997), obtaining the oxygen atoms. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Fe1 | 0.46063 (8) | 0.75449 (5) | 0.23372 (15) | 0.0096 (2) | 0.807 (7) |
Al1 | 0.46063 (8) | 0.75449 (5) | 0.23372 (15) | 0.0096 (2) | 0.193 (7) |
P1 | 0.37457 (11) | 0.63448 (9) | 0.7039 (2) | 0.0120 (3) | |
P2 | 0.53144 (11) | 0.88680 (8) | −0.2360 (3) | 0.0130 (3) | |
P3 | 0.20471 (11) | 0.84607 (8) | 0.0622 (2) | 0.0133 (3) | |
O1 | 0.3675 (3) | 0.6782 (2) | 0.4335 (8) | 0.0176 (8) | |
O2 | 0.4614 (3) | 0.6688 (2) | 0.9336 (8) | 0.0159 (8) | |
O3 | 0.2543 (3) | 0.6315 (3) | 0.8050 (8) | 0.0198 (8) | |
O4 | 0.4093 (4) | 0.5375 (3) | 0.6550 (9) | 0.0228 (9) | |
O5 | 0.4751 (4) | 0.8412 (3) | −0.4858 (8) | 0.0230 (9) | |
O6 | 0.5559 (3) | 0.8332 (3) | 0.0183 (8) | 0.0171 (8) | |
O7 | 0.6462 (3) | 0.9328 (3) | −0.2820 (9) | 0.0222 (9) | |
O8 | 0.4504 (3) | 0.9632 (3) | −0.1694 (8) | 0.0188 (8) | |
O9 | 0.1072 (3) | 0.7987 (3) | −0.1014 (9) | 0.0262 (10) | |
O10 | 0.3224 (3) | 0.8093 (3) | 0.0430 (8) | 0.0184 (8) | |
O11 | 0.1871 (4) | 0.8523 (3) | 0.3654 (9) | 0.0246 (9) | |
O12 | 0.2029 (4) | 0.9444 (3) | −0.0223 (12) | 0.0297 (9) | |
H3 | 0.203 (6) | 0.618 (5) | 0.671 (15) | 0.050* | |
H4 | 0.418 (7) | 0.510 (6) | 0.800 (13) | 0.050* | |
H7 | 0.678 (7) | 0.927 (5) | −0.435 (13) | 0.050* | |
H8 | 0.438 (6) | 0.996 (5) | −0.315 (14) | 0.050* | |
H11 | 0.152 (6) | 0.903 (4) | 0.403 (19) | 0.050* | |
H12 | 0.222 (7) | 0.959 (5) | −0.192 (11) | 0.050* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe1 | 0.0074 (3) | 0.0132 (4) | 0.0080 (3) | −0.0001 (3) | 0.0002 (2) | 0.0000 (3) |
Al1 | 0.0074 (3) | 0.0132 (4) | 0.0080 (3) | −0.0001 (3) | 0.0002 (2) | 0.0000 (3) |
P1 | 0.0111 (6) | 0.0142 (6) | 0.0109 (6) | −0.0013 (5) | 0.0020 (5) | −0.0005 (5) |
P2 | 0.0130 (6) | 0.0157 (6) | 0.0103 (6) | −0.0010 (5) | 0.0023 (5) | −0.0009 (5) |
P3 | 0.0093 (6) | 0.0165 (6) | 0.0138 (6) | −0.0008 (5) | 0.0010 (5) | −0.0003 (5) |
O1 | 0.0169 (18) | 0.0207 (19) | 0.0145 (19) | −0.0021 (15) | −0.0005 (16) | 0.0063 (15) |
O2 | 0.0129 (17) | 0.0198 (18) | 0.0145 (18) | −0.0012 (15) | 0.0003 (15) | −0.0035 (16) |
O3 | 0.0102 (17) | 0.035 (2) | 0.0147 (18) | −0.0014 (16) | 0.0020 (15) | 0.0018 (17) |
O4 | 0.027 (2) | 0.020 (2) | 0.021 (2) | 0.0025 (16) | 0.0028 (18) | −0.0005 (17) |
O5 | 0.027 (2) | 0.026 (2) | 0.015 (2) | −0.0036 (16) | −0.0007 (18) | −0.0060 (17) |
O6 | 0.0119 (18) | 0.025 (2) | 0.0144 (19) | −0.0034 (15) | 0.0015 (16) | 0.0028 (15) |
O7 | 0.0193 (19) | 0.027 (2) | 0.022 (2) | −0.0041 (17) | 0.0100 (17) | −0.0006 (18) |
O8 | 0.0196 (19) | 0.0198 (19) | 0.0179 (18) | 0.0010 (15) | 0.0055 (17) | −0.0009 (16) |
O9 | 0.0140 (18) | 0.041 (3) | 0.023 (2) | −0.0044 (18) | −0.0008 (17) | −0.0111 (19) |
O10 | 0.0107 (17) | 0.027 (2) | 0.0180 (18) | 0.0023 (15) | 0.0026 (15) | 0.0007 (17) |
O11 | 0.0197 (19) | 0.038 (2) | 0.017 (2) | −0.0033 (17) | 0.0055 (17) | −0.0053 (18) |
O12 | 0.031 (2) | 0.022 (2) | 0.039 (2) | 0.002 (2) | 0.0131 (19) | 0.006 (2) |
Fe1—O5i | 1.945 (4) | P3—O10 | 1.507 (4) |
Fe1—O10 | 1.958 (4) | P3—O11 | 1.570 (4) |
Fe1—O1 | 1.979 (4) | P3—O12 | 1.590 (4) |
Fe1—O9ii | 1.980 (4) | O2—Al1i | 2.017 (4) |
Fe1—O2iii | 2.017 (4) | O2—Fe1i | 2.017 (4) |
Fe1—O6 | 2.063 (4) | O3—H3 | 0.87 (5) |
P1—O1 | 1.513 (4) | O4—H4 | 0.84 (5) |
P1—O2 | 1.525 (4) | O5—Al1iii | 1.945 (4) |
P1—O3 | 1.563 (4) | O5—Fe1iii | 1.945 (4) |
P1—O4 | 1.593 (4) | O7—H7 | 0.90 (5) |
P2—O5 | 1.512 (4) | O8—H8 | 0.89 (5) |
P2—O6 | 1.521 (4) | O9—Al1iv | 1.980 (4) |
P2—O7 | 1.567 (4) | O9—Fe1iv | 1.980 (4) |
P2—O8 | 1.587 (4) | O11—H11 | 0.93 (5) |
P3—O9 | 1.504 (4) | O12—H12 | 0.94 (5) |
O5i—Fe1—O10 | 91.98 (17) | O7—P2—O8 | 103.7 (2) |
O5i—Fe1—O1 | 92.76 (18) | O9—P3—O10 | 114.1 (2) |
O10—Fe1—O1 | 92.04 (17) | O9—P3—O11 | 111.7 (2) |
O5i—Fe1—O9ii | 90.27 (19) | O10—P3—O11 | 109.3 (2) |
O10—Fe1—O9ii | 174.9 (2) | O9—P3—O12 | 110.2 (3) |
O1—Fe1—O9ii | 92.37 (17) | O10—P3—O12 | 109.1 (3) |
O5i—Fe1—O2iii | 174.10 (19) | O11—P3—O12 | 101.6 (3) |
O10—Fe1—O2iii | 90.69 (17) | P1—O1—Fe1 | 139.6 (2) |
O1—Fe1—O2iii | 92.40 (16) | P1—O2—Al1i | 136.6 (2) |
O9ii—Fe1—O2iii | 86.67 (18) | P1—O2—Fe1i | 136.6 (2) |
O5i—Fe1—O6 | 88.21 (17) | Al1i—O2—Fe1i | 0.00 (5) |
O10—Fe1—O6 | 87.29 (17) | P1—O3—H3 | 108 (6) |
O1—Fe1—O6 | 178.84 (18) | P1—O4—H4 | 111 (7) |
O9ii—Fe1—O6 | 88.25 (17) | P2—O5—Al1iii | 156.0 (3) |
O2iii—Fe1—O6 | 86.66 (17) | P2—O5—Fe1iii | 156.0 (3) |
O1—P1—O2 | 118.1 (2) | Al1iii—O5—Fe1iii | 0.00 (4) |
O1—P1—O3 | 111.5 (2) | P2—O6—Fe1 | 135.7 (2) |
O2—P1—O3 | 107.4 (2) | P2—O7—H7 | 123 (6) |
O1—P1—O4 | 105.7 (2) | P2—O8—H8 | 107 (6) |
O2—P1—O4 | 107.0 (2) | P3—O9—Al1iv | 169.0 (3) |
O3—P1—O4 | 106.4 (2) | P3—O9—Fe1iv | 169.0 (3) |
O5—P2—O6 | 116.7 (2) | Al1iv—O9—Fe1iv | 0.00 (3) |
O5—P2—O7 | 112.0 (3) | P3—O10—Fe1 | 146.5 (3) |
O6—P2—O7 | 108.1 (2) | P3—O11—H11 | 112 (6) |
O5—P2—O8 | 108.9 (2) | P3—O12—H12 | 119 (5) |
O6—P2—O8 | 106.4 (2) |
Symmetry codes: (i) x, y, z+1; (ii) x+1/2, −y+3/2, z+1/2; (iii) x, y, z−1; (iv) x−1/2, −y+3/2, z−1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O6v | 0.86 (7) | 1.94 (7) | 2.614 (5) | 134 (7) |
O3—H3···O7v | 0.86 (7) | 2.42 (8) | 3.207 (6) | 152 (7) |
O4—H4···O4vi | 0.84 (7) | 1.95 (7) | 2.775 (6) | 167 (8) |
O7—H7···O3vii | 0.91 (7) | 1.91 (7) | 2.765 (6) | 156 (7) |
O8—H8···O8viii | 0.89 (7) | 1.92 (7) | 2.764 (6) | 159 (7) |
O11—H11···O12ix | 0.92 (7) | 2.47 (6) | 3.220 (7) | 139 (6) |
O12—H12···O12viii | 0.94 (6) | 2.23 (7) | 3.055 (8) | 146 (7) |
Symmetry codes: (v) x−1/2, −y+3/2, z+1/2; (vi) x, −y+1, z+1/2; (vii) x+1/2, −y+3/2, z−3/2; (viii) x, −y+2, z−1/2; (ix) x, −y+2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | (Fe0.81Al0.19)(H2PO4)3 |
Mr | 341.32 |
Crystal system, space group | Monoclinic, Cc |
Temperature (K) | 293 |
a, b, c (Å) | 11.700 (1), 15.590 (1), 5.030 (1) |
β (°) | 98.00 (1) |
V (Å3) | 908.6 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.98 |
Crystal size (mm) | 0.15 × 0.15 × 0.1 |
Data collection | |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.703, 0.754 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1104, 1104, 1043 |
Rint | 0.000 |
(sin θ/λ)max (Å−1) | 0.636 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.074, 1.04 |
No. of reflections | 1104 |
No. of parameters | 166 |
No. of restraints | 10 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.55, −0.64 |
Absolute structure | Flack H D (1983), Acta Cryst. A39, 876-881 |
Absolute structure parameter | 0.00 (3) |
Computer programs: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992), MolEN (Fair, 1990), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999), WinGX (Farrugia, 1999).
Fe1—O5i | 1.945 (4) | P1—O4 | 1.593 (4) |
Fe1—O10 | 1.958 (4) | P2—O5 | 1.512 (4) |
Fe1—O1 | 1.979 (4) | P2—O6 | 1.521 (4) |
Fe1—O9ii | 1.980 (4) | P2—O7 | 1.567 (4) |
Fe1—O2iii | 2.017 (4) | P2—O8 | 1.587 (4) |
Fe1—O6 | 2.063 (4) | P3—O9 | 1.504 (4) |
P1—O1 | 1.513 (4) | P3—O10 | 1.507 (4) |
P1—O2 | 1.525 (4) | P3—O11 | 1.570 (4) |
P1—O3 | 1.563 (4) | P3—O12 | 1.590 (4) |
O5i—Fe1—O10 | 91.98 (17) | O5—P2—O6 | 116.7 (2) |
O5i—Fe1—O1 | 92.76 (18) | O5—P2—O7 | 112.0 (3) |
O10—Fe1—O1 | 92.04 (17) | O6—P2—O7 | 108.1 (2) |
O5i—Fe1—O9ii | 90.27 (19) | O5—P2—O8 | 108.9 (2) |
O10—Fe1—O9ii | 174.9 (2) | O6—P2—O8 | 106.4 (2) |
O1—Fe1—O9ii | 92.37 (17) | O7—P2—O8 | 103.7 (2) |
O5i—Fe1—O2iii | 174.10 (19) | O9—P3—O10 | 114.1 (2) |
O10—Fe1—O2iii | 90.69 (17) | O9—P3—O11 | 111.7 (2) |
O1—Fe1—O2iii | 92.40 (16) | O10—P3—O11 | 109.3 (2) |
O9ii—Fe1—O2iii | 86.67 (18) | O9—P3—O12 | 110.2 (3) |
O5i—Fe1—O6 | 88.21 (17) | O10—P3—O12 | 109.1 (3) |
O10—Fe1—O6 | 87.29 (17) | O11—P3—O12 | 101.6 (3) |
O1—Fe1—O6 | 178.84 (18) | P1—O1—Fe1 | 139.6 (2) |
O9ii—Fe1—O6 | 88.25 (17) | P1—O2—Al1i | 136.6 (2) |
O2iii—Fe1—O6 | 86.66 (17) | P1—O2—Fe1i | 136.6 (2) |
O1—P1—O2 | 118.1 (2) | P2—O5—Al1iii | 156.0 (3) |
O1—P1—O3 | 111.5 (2) | P2—O5—Fe1iii | 156.0 (3) |
O2—P1—O3 | 107.4 (2) | P2—O6—Fe1 | 135.7 (2) |
O1—P1—O4 | 105.7 (2) | P3—O9—Al1iv | 169.0 (3) |
O2—P1—O4 | 107.0 (2) | P3—O9—Fe1iv | 169.0 (3) |
O3—P1—O4 | 106.4 (2) | P3—O10—Fe1 | 146.5 (3) |
Symmetry codes: (i) x, y, z+1; (ii) x+1/2, −y+3/2, z+1/2; (iii) x, y, z−1; (iv) x−1/2, −y+3/2, z−1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O6v | 0.86 (7) | 1.94 (7) | 2.614 (5) | 134 (7) |
O3—H3···O7v | 0.86 (7) | 2.42 (8) | 3.207 (6) | 152 (7) |
O4—H4···O4vi | 0.84 (7) | 1.95 (7) | 2.775 (6) | 167 (8) |
O7—H7···O3vii | 0.91 (7) | 1.91 (7) | 2.765 (6) | 156 (7) |
O8—H8···O8viii | 0.89 (7) | 1.92 (7) | 2.764 (6) | 159 (7) |
O11—H11···O12ix | 0.92 (7) | 2.47 (6) | 3.220 (7) | 139 (6) |
O12—H12···O12viii | 0.94 (6) | 2.23 (7) | 3.055 (8) | 146 (7) |
Symmetry codes: (v) x−1/2, −y+3/2, z+1/2; (vi) x, −y+1, z+1/2; (vii) x+1/2, −y+3/2, z−3/2; (viii) x, −y+2, z−1/2; (ix) x, −y+2, z+1/2. |
Subscribe to Acta Crystallographica Section C: Structural Chemistry
The full text of this article is available to subscribers to the journal.
- Information on subscribing
- Sample issue
- Purchase subscription
- Reduced-price subscriptions
- If you have already subscribed, you may need to register
Microporous materials find their origin in the discovery by Crönsted during the thirteenth century of the zeolitic property of the mineral stilbite. The zeolite family is made up of the aluminosilicate minerals with formula [Mn+x/n[(AlO2)x(SiO2)y]x. wH2O], where x indicates the number of Mn+ cations necessary to compensate the negative charge of the whole framework. All these phases exhibit three-dimensional structures built up exclusively from corner-sharing TO4 (T = Al, Si) tetrahedra, defining tunnels in which the Mn+ cations and water molecules are located. Wilson et al. (1982) discovered a new family of compounds, the microporous aluminophosphates. Since 1992, the research groups of Cavellec (Cavellec et al., 1995; Cavellec, Riou & Férey, 1997; Cavellec, Férey & Grenèche, 1997; Riou-Cavellec et al., 1998) have been interested in the synthesis of these microporous materials. This work was followed by studies of microporous oxides by several groups (Debord et al., 1997; Lii & Huang, 1997a,b,c; Huang et al., 1998; Zima et al., 1998; Zima & Lii, 1998). Microporous materials derived from octahedral and tetrahedral frameworks currently boast an extensive chemistry and a number of them display useful properties as catalysts, sorbents and ionic exchangers (Davis & Lobo, 1992; Breck, 1974; Venuto, 1994).
Two polymorphs of Al(H2PO4)3 have been reported to date. The α-form is hexagonal with cell parameters a = 7.849 (1) and c = 24.87 (3) Å (Reference?), and the hexagonal β-form has parameters a = 13.69 (1) and c = 9.135 (1) Å (Yoire, 1961), also found by Brodalla et al. (1981). The α-form is isostructural with Fe(H2PO4)3 (Baies et al., 2006) and consists of a three-dimensional framework of corner-sharing FeO6 and PO2(OH)2 tetrahedra. The synthesis of a new monoclinic variety of iron aluminium phosphate, (Fe0.81Al0.19)(H2PO4)3 (γ-form), is reported in this work.
The compound (Fe0.81 Al0.19)(H2PO4)3 is composed of a highly puckered sheet structure containing interconnected M2P2 units (M = Fe or Al) connected laterally by Fe–O–P mixed bridges to form two-dimensional layers perpendicular to the b axis (Fig. 1). The oligomeric M2P2 units are built up from alternating corner-sharing of octahedral MO6 and tetrahedral PO4 units. The MO6 octahedra share six O atoms with adjacent P atoms, whereas the PO4 tetrahedra share only two O atoms. The projection of the sheet is shown in Fig. 2, viewed down the [010] axis. The M—O distances in (Fe0.81Al0.19)(H2PO4)3 have intermediate values between 1.944 (4) and 2.061 (4) Å, consistent with the occupation of Fe and Al valencies in these sites. The interatomic angles reveal distortions of the octahedra, varying from O6—Fe1—O2(x, y, z-1) = 86.66 (17)° to O1—Fe1—O6 = 178.84 (18)°. The dihydrogen phosphate ion, [H2PO4]-, can be described as slightly distorted tetrahedra, with a mean value for the P—OH bond distances of 1.578Å and with P═O bond distances ranging from 1.504 (4) to 1.525 (4)Å. The O—P—O angles are in the range 101.6 (3)–118.1 (2)°.
The crystal structure of (Fe0.81 Al0.19)(H2PO4)3 is characterized by an extended hydrogen-bonding network. The layers are held together through strong hydrogen bonds between the terminal O atoms attached to the two-connected phosphate groups in adjacent layers. Analysis of the hydrogen bonds in (Fe0.81Al0.19)(H2PO4)3 shows two different types of P—O—H···O—P bridges. Within the layer, adjacent H2PO4 ions are connected into chains by short hydrogen bonds with a distance of 2.614 (5) Å formed by one of the hydroxy groups, O3—H3···O6(x-1/2, -y+3/2, z+1/2). Adjacent layers are linked by longer hydrogen bonds, viz. O4—H4···O4(x, -y+1, z+1/2) [2.775 (6) Å], O12—H12···O12(x, -y+2, z-1/2) [3.056 (8) Å] and O11—H11···O12(x, -y+2, z+1/2) [3.223 (7) Å], which allow the layers to connect as observed in Fig. 1.
A comparison between (Fe0.81Al0.19)(H2PO4)3 and the series of compounds (NH4, H3O, K)(Fe,Al)3(HPO4)2(H2PO4)6.4H2O and [Al2P3O10(OH)2](C6NH8) is shown in Fig. 3. Detailed descriptions of their topology are also reported here. The aim of this comparison is to provide a review of possible approaches that can be used to establish the topology of microporous structures. For obvious reasons, we do not consider related octahedral–tetrahedral frameworks here. Most attention will be focused on network topology and the possibility of intercalating alkaline cations or organic molecules in the solid-state inorganic framework, which is important for both mineralogy and material sciences.
(Fe0.81Al0.19)(H2PO4) is considered an usual solid-state inorganic framework. A comparison between this compound and the series of compounds (NH4, H3O, K)(Fe,Al)3(HPO4)2(H2PO4)6.4H2O is shown in Fig. 3(a) and (b). The common characteristic of these compounds is their bidimensionality. In (NH4, H3O, K)(Fe,Al)3(HPO4)2(H2PO4)6.4H2O, the NH4+, H3O+ and K+ cations are located inside 12-sided polyhedra, which are generated by the corner-sharing MO6 (M = Fe, Al) and H2PO4 units, while water molecules are located in the interlayer space (Mgaidi et al., 1999; Bosman et al., 1986; Anisimova et al., 1997). Fig. 3(a) and (c) show the comparison between (Fe0.81Al0.19)(H2PO4)3 and the two-dimensional layered compound [Al2P3O10(OH)2](C6NH8). This structure contains macroanionic Al2P3O10(OH)2- sheets that are charge-balanced by protonated 4-methylpyridine. The inorganic layers are constructed from alternating Al-centred units (AlO4 and AlO5) and P-centred units [PO4, PO3(OH), PO2(═O)(OH)] with triply and doubly bridging phosphate groups (Yu et al., 2000). This comparison provides an example of the concept of scale chemistry (Férey, 2000). The cavities created by the framework, which are very small in typical solid-state inorganic frameworks and only able to accept alkaline cations or organic molecules, become larger and larger.
Please check that all references are cited correctly, especially those with similar authors in the same year.