Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803000837/br6074sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803000837/br6074Isup2.hkl |
CCDC reference: 202981
Crystals of Na1.79Mg1.79Fe1.21(PO4)3 were grown in a flux of sodium dimolybdate with a 1:1 molar ratio. Amounts of starting products corresponding to the stoichiometry of the crystals studied [Fe(NO3)3·9H2O, Mg(NO3)2·6H2O, NaH2PO4, (NH4)2HPO4 and MoO3] were mixed and gradually heated up to 873 K to allow ammonia, water and carbon dioxide to evolve. After a final grinding, the sample was melted for 1 h at 1173 K and then cooled down to room temperature with a rate of 10 K h−1. The crystals, obtained after washing with hot water to remove the flux, were yellow and presented elongated and parallelepipedic forms.
The Fe atoms were located by direct methods, and the remaining atoms were found by successive difference Fourier maps. The occupation number of the M2 site was constrained to 1.0 and the occupation number of the Na2 site was set equal to the partial occupation of Mg2 in the M2 site according to the Na1 + xMg1 + xFe2 − x(PO4)3 formula.
Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1998).
Fe1.21Mg1.79Na1.79O12P3 | F(000) = 854.5 |
Mr = 437.5 | Dx = 3.36 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 25 reflections |
a = 11.791 (3) Å | θ = 10–12° |
b = 12.489 (3) Å | µ = 2.93 mm−1 |
c = 6.4191 (10) Å | T = 293 K |
β = 113.82 (2)° | Parallelepiped, yellow |
V = 864.7 (4) Å3 | 0.25 × 0.15 × 0.1 mm |
Z = 4 |
Enraf-Nonius TurboCAD4 diffractometer | Rint = 0.014 |
non–profiled ω/2θ scans | θmax = 28.0°, θmin = 2.5° |
Absorption correction: analytical 'Alcock (1970)' | h = −15→14 |
Tmin = 0.59, Tmax = 0.73 | k = −16→0 |
1138 measured reflections | l = 0→8 |
1048 independent reflections | 2 standard reflections every 120 min |
982 reflections with I > 2σ(I) | intensity decay: none |
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)] = 0.023 | |
wR(F2) = 0.071 | (Δ/σ)max = 0.033 |
S = 1.15 | Δρmax = 0.48 e Å−3 |
1048 reflections | Δρmin = −0.75 e Å−3 |
98 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
2 constraints | Extinction coefficient: 0.0037 (6) |
Fe1.21Mg1.79Na1.79O12P3 | V = 864.7 (4) Å3 |
Mr = 437.5 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 11.791 (3) Å | µ = 2.93 mm−1 |
b = 12.489 (3) Å | T = 293 K |
c = 6.4191 (10) Å | 0.25 × 0.15 × 0.1 mm |
β = 113.82 (2)° |
Enraf-Nonius TurboCAD4 diffractometer | 982 reflections with I > 2σ(I) |
Absorption correction: analytical 'Alcock (1970)' | Rint = 0.014 |
Tmin = 0.59, Tmax = 0.73 | 2 standard reflections every 120 min |
1138 measured reflections | intensity decay: none |
1048 independent reflections |
R[F2 > 2σ(F2)] = 0.023 | 98 parameters |
wR(F2) = 0.071 | Δρmax = 0.48 e Å−3 |
S = 1.15 | Δρmin = −0.75 e Å−3 |
1048 reflections |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Fe2 | 0.21714 (4) | 0.15533 (3) | 0.12852 (7) | 0.00778 (16) | 0.6041 (6) |
Mg2 | 0.21714 (4) | 0.15533 (3) | 0.12852 (7) | 0.00778 (16) | 0.3960 (6) |
Mg1 | 0 | 0.26564 (9) | 0.25 | 0.0088 (2) | |
Na1 | 0.5 | 0 | 0 | 0.0234 (4) | |
Na2 | 0 | −0.0115 (3) | 0.25 | 0.0466 (7) | 0.7917 (13) |
P1 | 0.5 | 0.21062 (6) | 0.25 | 0.00583 (19) | |
O11 | 0.45796 (15) | 0.28120 (14) | 0.0322 (3) | 0.0087 (3) | |
O12 | 0.39708 (16) | 0.13456 (14) | 0.2493 (3) | 0.0123 (4) | |
P2 | 0.23741 (5) | 0.11008 (5) | 0.62617 (10) | 0.00601 (17) | |
O21 | 0.37541 (16) | 0.10417 (14) | 0.6758 (3) | 0.0112 (4) | |
O22 | 0.17902 (17) | −0.00119 (14) | 0.6170 (3) | 0.0118 (4) | |
O23 | 0.16302 (16) | 0.16543 (14) | 0.3925 (3) | 0.0098 (4) | |
O24 | 0.22191 (16) | 0.17812 (14) | 0.8158 (3) | 0.0099 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe2 | 0.0075 (2) | 0.0071 (2) | 0.0092 (2) | 0.00082 (15) | 0.00386 (18) | 0.00084 (15) |
Mg2 | 0.0075 (2) | 0.0071 (2) | 0.0092 (2) | 0.00082 (15) | 0.00386 (18) | 0.00084 (15) |
Mg1 | 0.0088 (5) | 0.0081 (5) | 0.0108 (5) | 0 | 0.0053 (4) | 0 |
Na1 | 0.0323 (9) | 0.0092 (7) | 0.0151 (8) | −0.0018 (6) | −0.0045 (7) | −0.0009 (6) |
Na2 | 0.0290 (14) | 0.0504 (18) | 0.0477 (18) | 0 | 0.0022 (13) | 0 |
P1 | 0.0057 (4) | 0.0051 (4) | 0.0062 (4) | 0 | 0.0020 (3) | 0 |
O11 | 0.0078 (7) | 0.0106 (8) | 0.0073 (7) | 0.0003 (6) | 0.0025 (6) | 0.0025 (6) |
O12 | 0.0090 (8) | 0.0095 (8) | 0.0173 (9) | −0.0016 (6) | 0.0042 (7) | 0.0037 (7) |
P2 | 0.0066 (3) | 0.0048 (3) | 0.0067 (3) | 0.00032 (19) | 0.0028 (2) | 0.0002 (2) |
O21 | 0.0087 (8) | 0.0093 (8) | 0.0166 (9) | 0.0005 (6) | 0.0060 (7) | −0.0002 (7) |
O22 | 0.0134 (8) | 0.0073 (7) | 0.0151 (9) | −0.0018 (7) | 0.0061 (7) | 0.0013 (7) |
O23 | 0.0116 (8) | 0.0081 (8) | 0.0090 (8) | 0.0013 (6) | 0.0036 (7) | 0.0005 (6) |
O24 | 0.0105 (8) | 0.0104 (8) | 0.0088 (8) | 0.0001 (6) | 0.0041 (6) | −0.0007 (6) |
Fe2—O12 | 1.9599 (19) | Na1—P1x | 3.0813 (9) |
Fe2—O22i | 1.9715 (19) | Na1—Na1viii | 3.2096 (5) |
Fe2—O23 | 2.0415 (18) | Na2—O22 | 2.451 (2) |
Fe2—O24ii | 2.0506 (18) | Na2—O22i | 2.5816 (19) |
Fe2—O11iii | 2.0579 (18) | Na2—O23 | 2.827 (3) |
Fe2—O24iv | 2.1825 (19) | Na2—O11xi | 2.889 (3) |
Fe2—Mg2iii | 3.1539 (10) | Na2—Na2xii | 3.2223 (8) |
Fe2—Na2v | 3.265 (2) | Na2—P2 | 3.2420 (18) |
Fe2—Mg1 | 3.2670 (9) | P1—O12viii | 1.5398 (18) |
Mg1—O21iv | 2.113 (2) | P1—O11viii | 1.5547 (17) |
Mg1—O11iii | 2.1436 (17) | P1—Mg2xiii | 3.1995 (10) |
Mg1—O23vi | 2.1628 (19) | P2—O21 | 1.5283 (18) |
Mg1—Na1vii | 3.3380 (12) | P2—O22 | 1.5414 (18) |
Na1—O12viii | 2.3041 (18) | P2—O24 | 1.5546 (18) |
Na1—O21ix | 2.3898 (19) | P2—O23 | 1.5601 (18) |
Na1—O21i | 2.5424 (18) | P2—Na1xiv | 3.3517 (11) |
Na1—O12x | 2.9030 (19) | ||
O12—Fe2—O22i | 94.56 (8) | O12viii—Na1—O12x | 125.99 (7) |
O12—Fe2—O23 | 109.33 (8) | O12i—Na1—O12x | 54.01 (7) |
O22i—Fe2—O23 | 87.05 (7) | O21ix—Na1—O12x | 85.30 (6) |
O12—Fe2—O24ii | 87.27 (8) | O21ii—Na1—O12x | 94.70 (6) |
O22i—Fe2—O24ii | 101.23 (8) | O21i—Na1—O12x | 113.19 (5) |
O23—Fe2—O24ii | 160.97 (7) | O21viii—Na1—O12x | 66.81 (5) |
O12—Fe2—O11iii | 162.93 (7) | O12viii—Na1—O12 | 54.01 (7) |
O22i—Fe2—O11iii | 100.95 (7) | O22—Na2—O22vi | 174.00 (17) |
O23—Fe2—O11iii | 78.80 (7) | O22—Na2—O22i | 79.21 (6) |
O24ii—Fe2—O11iii | 82.78 (7) | O22vi—Na2—O22i | 100.41 (6) |
O12—Fe2—O24iv | 80.16 (7) | O22i—Na2—O22xii | 172.99 (16) |
O22i—Fe2—O24iv | 172.65 (7) | O22—Na2—O23 | 55.87 (7) |
O23—Fe2—O24iv | 89.88 (7) | O22vi—Na2—O23 | 118.64 (12) |
O24ii—Fe2—O24iv | 83.72 (7) | O22i—Na2—O23 | 61.27 (7) |
O11iii—Fe2—O24iv | 84.97 (7) | O22xii—Na2—O23 | 112.65 (10) |
O21iv—Mg1—O21xv | 79.36 (10) | O23—Na2—O23vi | 77.21 (11) |
O21iv—Mg1—O11iii | 91.34 (7) | O22—Na2—O11xi | 115.15 (11) |
O21xv—Mg1—O11iii | 113.37 (7) | O22vi—Na2—O11xi | 70.66 (7) |
O11iii—Mg1—O11xvi | 148.33 (11) | O22i—Na2—O11xi | 84.16 (7) |
O21iv—Mg1—O23vi | 163.53 (8) | O22xii—Na2—O11xi | 102.21 (9) |
O21xv—Mg1—O23vi | 86.08 (7) | O23—Na2—O11xi | 144.92 (5) |
O11iii—Mg1—O23vi | 87.36 (7) | O23vi—Na2—O11xi | 125.63 (5) |
O11xvi—Mg1—O23vi | 74.35 (7) | O11xi—Na2—O11xvii | 52.63 (9) |
O21xv—Mg1—O23 | 163.53 (8) | O12viii—P1—O12 | 103.82 (14) |
O23vi—Mg1—O23 | 109.29 (11) | O12viii—P1—O11viii | 112.49 (9) |
O12viii—Na1—O12i | 180.00 (11) | O12—P1—O11viii | 108.48 (9) |
O12viii—Na1—O21ix | 79.85 (6) | O11viii—P1—O11 | 110.92 (14) |
O12viii—Na1—O21ii | 100.15 (6) | O21—P2—O22 | 112.70 (10) |
O12viii—Na1—O21i | 107.40 (6) | O21—P2—O24 | 108.36 (10) |
O12i—Na1—O21i | 72.60 (6) | O22—P2—O24 | 109.31 (10) |
O21ix—Na1—O21i | 66.24 (7) | O21—P2—O23 | 111.09 (10) |
O21ii—Na1—O21i | 113.76 (7) | O22—P2—O23 | 107.08 (10) |
O21i—Na1—O21viii | 180 | O24—P2—O23 | 108.21 (10) |
Symmetry codes: (i) x, −y, z−1/2; (ii) x, y, z−1; (iii) −x+1/2, −y+1/2, −z; (iv) −x+1/2, −y+1/2, −z+1; (v) −x, −y, −z; (vi) −x, y, −z+1/2; (vii) −x+1/2, y+1/2, −z+1/2; (viii) −x+1, y, −z+1/2; (ix) −x+1, −y, −z+1; (x) −x+1, −y, −z; (xi) x−1/2, y−1/2, z; (xii) −x, −y, −z+1; (xiii) x+1/2, −y+1/2, z+1/2; (xiv) x, y, z+1; (xv) x−1/2, −y+1/2, z−1/2; (xvi) x−1/2, −y+1/2, z+1/2; (xvii) −x+1/2, y−1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | Fe1.21Mg1.79Na1.79O12P3 |
Mr | 437.5 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 11.791 (3), 12.489 (3), 6.4191 (10) |
β (°) | 113.82 (2) |
V (Å3) | 864.7 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.93 |
Crystal size (mm) | 0.25 × 0.15 × 0.1 |
Data collection | |
Diffractometer | Enraf-Nonius TurboCAD4 diffractometer |
Absorption correction | Analytical 'Alcock (1970)' |
Tmin, Tmax | 0.59, 0.73 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1138, 1048, 982 |
Rint | 0.014 |
(sin θ/λ)max (Å−1) | 0.660 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.071, 1.15 |
No. of reflections | 1048 |
No. of parameters | 98 |
No. of restraints | ? |
Δρmax, Δρmin (e Å−3) | 0.48, −0.75 |
Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1994), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1998).
Fe2—O12 | 1.9599 (19) | Na1—O12viii | 2.9030 (19) |
Fe2—O22i | 1.9715 (19) | Na2—O22 | 2.451 (2) |
Fe2—O23 | 2.0415 (18) | Na2—O22i | 2.5816 (19) |
Fe2—O24ii | 2.0506 (18) | Na2—O23 | 2.827 (3) |
Fe2—O11iii | 2.0579 (18) | Na2—O11ix | 2.889 (3) |
Fe2—O24iv | 2.1825 (19) | P1—O12vi | 1.5398 (18) |
Mg1—O21iv | 2.113 (2) | P1—O11vi | 1.5547 (17) |
Mg1—O11iii | 2.1436 (17) | P2—O21 | 1.5283 (18) |
Mg1—O23v | 2.1628 (19) | P2—O22 | 1.5414 (18) |
Na1—O12vi | 2.3041 (18) | P2—O24 | 1.5546 (18) |
Na1—O21vii | 2.3898 (19) | P2—O23 | 1.5601 (18) |
Na1—O21i | 2.5424 (18) | ||
O12—Fe2—O22i | 94.56 (8) | O11iii—Mg1—O11xi | 148.33 (11) |
O12—Fe2—O23 | 109.33 (8) | O21iv—Mg1—O23v | 163.53 (8) |
O22i—Fe2—O23 | 87.05 (7) | O21x—Mg1—O23v | 86.08 (7) |
O12—Fe2—O24ii | 87.27 (8) | O11iii—Mg1—O23v | 87.36 (7) |
O22i—Fe2—O24ii | 101.23 (8) | O11xi—Mg1—O23v | 74.35 (7) |
O23—Fe2—O24ii | 160.97 (7) | O21x—Mg1—O23 | 163.53 (8) |
O12—Fe2—O11iii | 162.93 (7) | O23v—Mg1—O23 | 109.29 (11) |
O22i—Fe2—O11iii | 100.95 (7) | O12vi—P1—O12 | 103.82 (14) |
O23—Fe2—O11iii | 78.80 (7) | O12vi—P1—O11vi | 112.49 (9) |
O24ii—Fe2—O11iii | 82.78 (7) | O12—P1—O11vi | 108.48 (9) |
O12—Fe2—O24iv | 80.16 (7) | O11vi—P1—O11 | 110.92 (14) |
O22i—Fe2—O24iv | 172.65 (7) | O21—P2—O22 | 112.70 (10) |
O23—Fe2—O24iv | 89.88 (7) | O21—P2—O24 | 108.36 (10) |
O24ii—Fe2—O24iv | 83.72 (7) | O22—P2—O24 | 109.31 (10) |
O11iii—Fe2—O24iv | 84.97 (7) | O21—P2—O23 | 111.09 (10) |
O21iv—Mg1—O21x | 79.36 (10) | O22—P2—O23 | 107.08 (10) |
O21iv—Mg1—O11iii | 91.34 (7) | O24—P2—O23 | 108.21 (10) |
O21x—Mg1—O11iii | 113.37 (7) |
Symmetry codes: (i) x, −y, z−1/2; (ii) x, y, z−1; (iii) −x+1/2, −y+1/2, −z; (iv) −x+1/2, −y+1/2, −z+1; (v) −x, y, −z+1/2; (vi) −x+1, y, −z+1/2; (vii) −x+1, −y, −z+1; (viii) −x+1, −y, −z; (ix) x−1/2, y−1/2, z; (x) x−1/2, −y+1/2, z−1/2; (xi) x−1/2, −y+1/2, z+1/2. |
The phosphates with the alluaudite structure type (monoclinic C2/c, Z = 4) (Moore, 1971) are studied quite frequently. These materials present the X(2)X(1)M(1)M(2)2(PO4)3 general formula and are known to be highly susceptible to substitution in the X(2), X(1), M(1) and M(2) sites, which can incorporate a variety of cations with different ionic radii and charges, leading to the formation of solid solutions in large composition domains (Hatert et al., 2000, 2002).
During an investigation of monophosphates belonging to the Na3PO4—Mg3(PO4)2-FePO4 system, in order to clear up the role of Mg2+ in the crystal chemistry of such materials, we have isolated the Na1 + xMg1 + xFe2 − x(PO4)3 (x from 0.5 to 1) alluaudite-like solid solution. The structure of the x = 0.79 composition was determined by X-ray diffraction. This structure, as viewed along the [001] direction, is shown in Fig. 1. It consists of M22O10 (M2 = 0.4 Mg2 + 0.6 Fe2) units of edge-sharing M2O6 octahedra. These units share opposite edges with Mg1O6 octahedra to form infinite –M2—M2—Mg1- chains running along the [101] direction (Fig. 2). These chains are linked to similar neighboring chains via common corners of P1O4 and P2O4 tetrahedra. The P1O4 tetrahedron connects two chains by sharing each pair of its O atoms with one chain. The P2O4 tetrahedron connects three adjacent chains by sharing two of its O atoms with one chain and the remaining two O atoms with two different chains.
The three-dimensional framework constructed in this way generates two crystallographically independant tunnels growing along the c axis. These tunnels, located at 0,0,z and at 1/2,0,z, respectively, are available for the Na+ cations.
Table 1 lists main bond distances and angles in Na1.79Mg1.79Fe1.21(PO4)3. The M2O6 octahedron is distorted as indicated by the M2—O bond lengths and O—M2—O bond angles. Such distortion can be correlated to the rigidity of phosphates groups which connect the chains. The Mg1O6 octahedron is more distorted than M2O6. However, the average Mg1—O distance is consistent with those observed in other phosphates containing Mg2+ in an octahedral environment (Alkemper & Fuess, 1998).
The interatomic distances in the phosphate tetrahedra are similar to those observed in phosphates without hydrogen bonding (Corbin et al., 1986; Korzenski et al., 1998; Warner et al., 1993). The P1O4 tetrahedron is slightly more regular than P2O4, which is in accordance with the fact that the P1 atom sits in a twofold axis, while atom P2 is located in a general position.
The coordination environment of each sodium ion was determined assuming Na—O distances below 3.0 Å. Na1 has a very distorted cubic environment. Each Na1O8 polyhedron shares faces with equivalent polyhedra that form chains in the c direction. The Na2 site is partially filled with an occupation number of 0.79. This site has a strongly irregular environment which consists of four O atoms at short distances and four others at rather long distances.
The structure of Na1.79Mg1.79Fe1.21(PO4)3 was compared to that of the natural alluaudite from the Buragna pegmatite of Central Africa (Moore, 1971). In spite of numerous similarities, the two compounds are not isostructural, since the cation distribution within the sites in the tunnels is not exactly the same. In fact, in the title compound, the X(2) site (at 0, ~0, 0) is partially occupied while the X(1) site (at 1/2, 0, 0) is totally filled with Na+ cations. By contrast, the natural alluaudite of Buragna features an X(1) site partially occupied by Na+ and Ca2+ cations and an empty X(2) site.