research communications
Synthesis, 2.22Mn0.87In1.68(PO4)3
and charge-distribution validation of a new alluaudite-type phosphate, NaaLaboratory of Interfacial and Advanced Materials, Faculty of Sciences (FSM), University of Monastir, Monastir 5000, Tunisia, and bDepartamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain
*Correspondence e-mail: badri_abdessalem@yahoo.fr
Na2.22Mn0.87In1.68(PO4)3, sodium manganese indium tris(phosphate) (2.22/0.87/1.68), was obtained in the form of single crystals by a method and was structurally characterized by single-crystal X-ray diffraction. The compound belongs to the alluaudite structure type (space group C2/c) with general formula X(2)X(1)M(1)M(2)2(PO4)3. The X(2) and X(1) sites are partially occupied by sodium [occupancy 0.7676 (17) and 1/2] while the M(1) and M(2) sites are fully occupied within a mixed distribution of sodium/manganese(II) and manganese(II)/indium, respectively. The three-dimensional anionic framework is built up on the basis of M(2)2O10 dimers that share opposite edges with M(1)O6 octahedra, thus forming infinite chains extending parallel to [10]. The linkage between these chains is ensured by PO4 tetrahedra through common vertices. The three-dimensional network thus constructed delimits two types of hexagonal channels, resulting from the catenation of M(2)2O10 dimers, M(1)O6 octahedra and PO4 tetrahedra through edge- and corner-sharing. The channels are occupied by Na+ cations with coordination numbers of seven and eight.
Keywords: crystal structure; indium phosphate; alluaudite structure type; disorder.
CCDC reference: 2018562
1. Chemical context
The general A(2)A(2)][A(1)A(1)'A(1)''2]M(1)M(2)2(PO4)3 (Hatert et al., 2000); in the majority of natural alluaudites, the large crystallographic A sites are occupied by Na+, Ca2+ or Mn2+, and the distorted-octahedrally surrounded M sites are occupied by Mn2+, Fe2+, Fe3+, Al3+ or Mg2+ (Moore & Ito, 1979). Alluaudite-type phosphates are frequently used for practical applications such as corrosion inhibition, passivation of metal surfaces, or catalysis (Korzenski et al., 1998; Kacimi et al., 2005). Furthermore, as a result of the presence of channels, alluaudite-type compounds exhibit electronic and/or properties (Warner et al., 1994; Durio et al., 2002). The possibility of inserting variable amounts of lithium into the channels of the alluaudite structure also makes the (Na1–xLix)MnFe3+2(PO4)3 and (Na1–xLix)1.5Mn1.5Fe3+1.5(PO4)3 compounds of value as potential battery materials (Hatert et al., 2004; Trad et al., 2018). A number of indium-bearing alluaudite-like compounds have also been synthesized, i.e. NaCdIn2(PO4)3 (Antenucci et al., 1993), Na3In2(PO4)3 (Lii & Ye, 1997), and NaMn(Fe1–xInx)2(PO4)3 (Hatert et al., 2003). In this paper, we report the structural study of a new alluaudite-type phosphate, Na2.22Mn0.87In1.68(PO4)3, which was obtained during our investigation of the Na3PO4–Mn3(PO4)2–InPO4 quasi system.
of alluaudite-type phosphates is [2. Structural commentary
The principal building units (Fig. 1) of the three-dimensional framework structure of Na2.22Mn0.87In1.68(PO4)3 are mixed-occupancy (Mn, Na) [= M(1); 2] and (Mn1, In) [= M(2)] sites with distorted octahedral environments and two phosphate tetrahedra (P1 and P2); the two sites associated with Na+ cations (Na1; Na2 with 2) are partially occupied and are situated in the resulting voids. By edge-sharing, the (Mn,In)O6 octahedra form (Mn,In)2O10 dimers, which are linked by highly distorted (Mn,Na)O6 octahedra into infinite zigzag chains along [10] (Fig. 2). The connection of these chains through vertices belonging to P1O4 and P2O4 tetrahedra gives layers perpendicular to [010] (Fig. 3), which, in turn, are linked into the three-dimensional framework by sharing corners with phosphate tetrahedra. This framework accommodates two types of channels extending parallel to [001] in which the Na+ cations are located (Fig. 4).
The mean <M1—O> distance of 2.329 Å is between those of 2.23 and 2.42 Å predicted by the sums of the ionic radii (Shannon, 1976) for Mn2+ and Na+ cations in an octahedral environment. The mean <M2—O> distance of 2.150 Å is between the mean distance of 2.142 Å observed for In3+ in an octahedral environment in NaCuIn(PO4)2 (Benhsina et al., 2020) and 2.238 Å for Mn2+ in the same coordination in K0.53Mn2.37Fe1.24(PO4)3 (Hidouri & Ben Amara, 2011). The PO4 tetrahedra show a slight distortion, as indicated by the range of P—O bond lengths [1.538 (2)–1.550 (2) Å for P1O4 and 1.520 (3)–1.566 (2) Å for P2O4], with mean bond lengths of <P1—O> = 1.544 (2) Å and <P2—O> = 1.546 (2) Å, consistent with 1.537 Å as calculated by Baur (1974) for the orthophosphate group. The coordination spheres of the two crystallographically distinct Na sites (Fig. 1) in the channels were defined under the assumption of a maximum Na—O distance Lmax = 3.13 Å, suggested by Donnay & Allmann (1970). The environment around Na1 consists of seven O atoms with distances varying from 2.35 (3) to 2.99 (3) Å, and Na2 is bound to eight O atoms with distances in the range 2.510 (3)–2.928 (6) Å.
The refined structure model is confirmed by (i) the bond-valence method (Brown & Altermatt, 1985; Brown, 2002) and (ii) the charge-distribution (Chardi) method (Nespolo, 2015, 2016). The Chardi method is a development of Pauling's concept of bond strength (Pauling, 1929). Instead of the empirical parameters used in the bond-valence approach, it exploits the experimental bond lengths deduced from the structural study to compute a non-integer (effective = ECoN) around a PC atom (atom placed at the center of a polyhedron, q > 0), which is coordinated by V atoms (atoms located at the vertices; q < 0); q is the formal ECoN takes into account not only the number of V atoms around a given PC atom, but also their weight in terms of relative distances. Calculated charges Q(i) and valences V(i) are in good agreement with the formal (q) multiplied by occupancy rates. The dispersion factor MAPD, , which measures the mean absolute percentage deviation, is 1% for the calculated cationic charges. The variation of the ECoN value with respect to the traditional indicates the degree of distortion. The results of the two validation models are compiled in Table 1.
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3. Synthesis and crystallization
Commercially available NaNO3, Mn(NO3)2·6H2O, In2O3, MoO3 and (NH4)2HPO4 were mixed in stoichiometric ratios of 2:1:1:1:2 and dissolved in aqueous nitric acid. The resulting solution was then evaporated by heating at 353 K. The obtained dry residue was ground in an agate mortar, and then heated increasingly in an open platinum crucible up to 873 K. The sample was then reground and mixed with sodium dimolybdate Na2Mo2O7 in the molar ratio P:Mo = 2:1. The mixture was heated for 1 h at 1243 K to give a melt that was subsequently cooled down to room temperature at a rate of 10 K h−1. Brown hexagonally shaped crystals were obtained by washing the final product with hot water in order to dissolve the flux.
4. Refinement
Crystal data, data collection and structure . The bond lengths involving M1—O and M2—O are those between the mean Na—O and Mn—O and the mean In—O and Mn—O bond lengths, respectively. We used EADP, EXYZ and SUMP constraints within SHELXL2018/3 (Sheldrick, 2015) for the mixed-occupied M1 [refined ratio Mn:Na = 0.5438 (14):0.4562 (14)] and M2 [refined ratio In:Mn = 0.8443 (5):0.1557 (5)] sites. Na2 shows an occupancy of 0.7676 (17), and free of the occupancy of Na1 resulted in a value very close to 0.5. For the final this value was fixed at 0.5, and all other occupancies were refined to ensure electrical neutrality of the compound. The remaining maximum and minimum electron densities are located 0.74 Å from P2 and 1.07 Å from O24, respectively.
details are summarized in Table 2Supporting information
CCDC reference: 2018562
https://doi.org/10.1107/S2056989020010191/wm5566sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020010191/wm5566Isup2.hkl
CHARDI and BVS analysis of cation polyhedra in Na2.22Mn0.87In1.68(PO4)3. DOI: https://doi.org/10.1107/S2056989020010191/wm5566sup3.docx
Data collection: KappaCCD Server Software (Nonius, 1997); cell
HKL SCALEPACK (Otwinovski & Minor, 1997); data reduction: HKL DENZO (Otwinovski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 2012).Na2.22Mn0.87In1.68(PO4)3 | F(000) = 1100 |
Mr = 575.82 | Dx = 4.115 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 25 reflections |
a = 12.412 (2) Å | θ = 3.2–28.9° |
b = 12.855 (2) Å | µ = 5.81 mm−1 |
c = 6.599 (1) Å | T = 293 K |
β = 114.727 (2)° | Prism, brown |
V = 956.4 (3) Å3 | 0.29 × 0.17 × 0.11 mm |
Z = 4 |
Nonius Kappa CCD diffractometer | 1172 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
non–profiled ω/2τ scans | θmax = 28.9°, θmin = 2.4° |
Absorption correction: part of the (Parkin et al., 1995) | model (ΔF) h = −16→14 |
Tmin = 0.178, Tmax = 0.222 | k = 0→16 |
1183 measured reflections | l = 0→8 |
1183 independent reflections |
Refinement on F2 | 3 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.021 | w = 1/[σ2(Fo2) + (0.0135P)2 + 7.1094P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.054 | (Δ/σ)max = 0.023 |
S = 1.31 | Δρmax = 0.73 e Å−3 |
1183 reflections | Δρmin = −0.83 e Å−3 |
102 parameters |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Na1 | 0.492 (3) | 0.003 (3) | 0.013 (5) | 0.017 (2) | 0.5 |
Na2 | 0 | −0.0079 (4) | 0.75 | 0.0586 (13) | 0.7676 (17) |
Mn | 0.5 | 0.22924 (8) | 0.25 | 0.0128 (2) | 0.5438 (14) |
Na | 0.5 | 0.22924 (8) | 0.25 | 0.0128 (2) | 0.4562 (14) |
In | 0.22327 (2) | 0.15486 (2) | 0.64458 (4) | 0.00781 (9) | 0.8443 (5) |
Mn1 | 0.22327 (2) | 0.15486 (2) | 0.64458 (4) | 0.00781 (9) | 0.1557 (5) |
P1 | 0.5 | 0.21702 (9) | 0.75 | 0.0075 (2) | |
O11 | 0.5471 (2) | 0.2867 (2) | 0.9611 (4) | 0.0138 (5) | |
O12 | 0.4072 (2) | 0.14288 (19) | 0.7683 (4) | 0.0140 (5) | |
P2 | 0.23767 (7) | 0.10662 (6) | 1.13105 (13) | 0.00841 (17) | |
O21 | 0.1736 (3) | 0.0029 (2) | 1.1238 (4) | 0.0172 (5) | |
O22 | 0.2293 (2) | 0.17542 (19) | 1.3198 (4) | 0.0112 (5) | |
O23 | 0.1663 (2) | 0.16388 (19) | 0.9065 (4) | 0.0139 (5) | |
O24 | 0.3668 (2) | 0.0921 (2) | 1.1731 (5) | 0.0206 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Na1 | 0.023 (7) | 0.013 (3) | 0.012 (5) | 0.004 (4) | 0.005 (3) | −0.002 (3) |
Na2 | 0.027 (2) | 0.073 (3) | 0.055 (3) | 0 | −0.0025 (19) | 0 |
Mn | 0.0146 (5) | 0.0121 (5) | 0.0141 (5) | 0 | 0.0083 (4) | 0 |
Na | 0.0146 (5) | 0.0121 (5) | 0.0141 (5) | 0 | 0.0083 (4) | 0 |
In | 0.00802 (13) | 0.00782 (13) | 0.00813 (14) | 0.00050 (8) | 0.00390 (10) | 0.00093 (8) |
Mn1 | 0.00802 (13) | 0.00782 (13) | 0.00813 (14) | 0.00050 (8) | 0.00390 (10) | 0.00093 (8) |
P1 | 0.0062 (5) | 0.0092 (5) | 0.0055 (5) | 0 | 0.0008 (4) | 0 |
O11 | 0.0097 (11) | 0.0174 (12) | 0.0121 (11) | 0.0005 (9) | 0.0024 (9) | −0.0062 (9) |
O12 | 0.0083 (11) | 0.0139 (12) | 0.0184 (13) | −0.0007 (9) | 0.0042 (10) | 0.0045 (9) |
P2 | 0.0131 (4) | 0.0069 (4) | 0.0063 (4) | 0.0012 (3) | 0.0051 (3) | 0.0005 (3) |
O21 | 0.0287 (14) | 0.0080 (11) | 0.0163 (13) | 0.0006 (10) | 0.0108 (11) | 0.0008 (9) |
O22 | 0.0154 (12) | 0.0105 (11) | 0.0081 (11) | −0.0003 (9) | 0.0053 (9) | −0.0005 (9) |
O23 | 0.0232 (13) | 0.0120 (12) | 0.0079 (11) | 0.0027 (9) | 0.0079 (10) | 0.0021 (9) |
O24 | 0.0201 (14) | 0.0249 (14) | 0.0206 (14) | 0.0084 (11) | 0.0124 (11) | 0.0071 (11) |
Na1—O12i | 2.35 (3) | Mn—O23xi | 2.330 (3) |
Na1—O12ii | 2.38 (3) | Mn—O11iii | 2.335 (3) |
Na1—O24iii | 2.38 (3) | Mn—O11i | 2.335 (3) |
Na1—O24iv | 2.45 (3) | In—O12 | 2.084 (2) |
Na1—O24i | 2.489 (18) | In—O21v | 2.107 (3) |
Na1—O24ii | 2.811 (17) | In—O23 | 2.127 (3) |
Na1—O12v | 2.99 (3) | In—O11xii | 2.144 (2) |
Na2—O21 | 2.510 (3) | In—O22i | 2.192 (2) |
Na2—O21vi | 2.510 (3) | In—O22xiii | 2.246 (2) |
Na2—O21v | 2.616 (3) | P1—O12 | 1.538 (2) |
Na2—O21vii | 2.616 (3) | P1—O12iii | 1.538 (2) |
Na2—O23vi | 2.901 (5) | P1—O11iii | 1.550 (2) |
Na2—O23 | 2.901 (5) | P1—O11 | 1.550 (2) |
Na2—O11viii | 2.928 (6) | P2—O24 | 1.520 (3) |
Na2—O11ix | 2.928 (6) | P2—O21 | 1.543 (3) |
Mn—O24i | 2.323 (3) | P2—O23 | 1.557 (3) |
Mn—O24iii | 2.323 (3) | P2—O22 | 1.566 (2) |
Mn—O23x | 2.330 (3) | ||
O12i—Na1—O12ii | 172.0 (8) | O21vii—Na2—O11ix | 84.12 (12) |
O12i—Na1—O24iii | 100.6 (13) | O23vi—Na2—O11ix | 145.72 (9) |
O12ii—Na1—O24iii | 80.8 (10) | O23—Na2—O11ix | 123.11 (7) |
Na1xiv—Na1—O24iv | 73 (10) | O11viii—Na2—O11ix | 51.21 (13) |
O12i—Na1—O24iv | 79.9 (10) | O24i—Mn—O24iii | 81.29 (13) |
O12ii—Na1—O24iv | 97.6 (12) | O24i—Mn—O23x | 164.09 (10) |
O24iii—Na1—O24iv | 172.4 (9) | O24iii—Mn—O23x | 86.16 (9) |
O12i—Na1—O24i | 76.2 (8) | O24i—Mn—O23xi | 86.16 (9) |
O12ii—Na1—O24i | 111.7 (10) | O24iii—Mn—O23xi | 164.09 (10) |
O24iii—Na1—O24i | 76.9 (7) | O23x—Mn—O23xi | 107.74 (13) |
O24iv—Na1—O24i | 110.6 (11) | O24i—Mn—O11iii | 91.16 (9) |
O12i—Na1—O24ii | 102.3 (8) | O24iii—Mn—O11iii | 117.37 (9) |
O12ii—Na1—O24ii | 69.7 (6) | O23x—Mn—O11iii | 85.95 (9) |
O24iii—Na1—O24ii | 102.7 (9) | O23xi—Mn—O11iii | 72.40 (9) |
O24iv—Na1—O24ii | 69.8 (6) | O24i—Mn—O11i | 117.37 (9) |
O24i—Na1—O24ii | 178.4 (15) | O24iii—Mn—O11i | 91.16 (9) |
O12i—Na1—O12v | 135.0 (10) | O23x—Mn—O11i | 72.40 (9) |
O12ii—Na1—O12v | 51.9 (6) | O23xi—Mn—O11i | 85.95 (9) |
O24iii—Na1—O12v | 96.7 (9) | O11iii—Mn—O11i | 143.12 (14) |
O24iv—Na1—O12v | 88.1 (10) | O12—In—O21v | 101.37 (10) |
O24i—Na1—O12v | 67.8 (5) | O12—In—O23 | 111.59 (10) |
O24ii—Na1—O12v | 113.8 (11) | O21v—In—O23 | 85.28 (10) |
O21—Na2—O21vi | 173.7 (3) | O12—In—O11xii | 159.80 (10) |
O21—Na2—O21v | 80.14 (8) | O21v—In—O11xii | 95.68 (10) |
O21vi—Na2—O21v | 99.71 (8) | O23—In—O11xii | 80.34 (10) |
O21—Na2—O21vii | 99.71 (8) | O12—In—O22i | 84.96 (10) |
O21vi—Na2—O21vii | 80.14 (8) | O21v—In—O22i | 100.43 (10) |
O21v—Na2—O21vii | 177.2 (3) | O23—In—O22i | 161.27 (10) |
O21—Na2—O23vi | 119.88 (19) | O11xii—In—O22i | 81.35 (9) |
O21vi—Na2—O23vi | 54.39 (10) | O12—In—O22xiii | 80.47 (9) |
O21v—Na2—O23vi | 115.22 (16) | O21v—In—O22xiii | 176.57 (10) |
O21vii—Na2—O23vi | 62.40 (10) | O23—In—O22xiii | 91.36 (9) |
O21—Na2—O23 | 54.39 (10) | O11xii—In—O22xiii | 83.08 (9) |
O21vi—Na2—O23 | 119.88 (19) | O22i—In—O22xiii | 82.57 (9) |
O21v—Na2—O23 | 62.40 (10) | O12—P1—O12iii | 103.4 (2) |
O21vii—Na2—O23 | 115.22 (16) | O12—P1—O11iii | 114.56 (13) |
O23vi—Na2—O23 | 80.89 (17) | O12iii—P1—O11iii | 107.48 (14) |
O21—Na2—O11viii | 115.83 (18) | O12—P1—O11 | 107.48 (14) |
O21vi—Na2—O11viii | 70.36 (11) | O12iii—P1—O11 | 114.56 (13) |
O21v—Na2—O11viii | 84.12 (12) | O11iii—P1—O11 | 109.4 (2) |
O21vii—Na2—O11viii | 98.43 (14) | O24—P2—O21 | 112.98 (16) |
O23vi—Na2—O11viii | 123.11 (7) | O24—P2—O23 | 111.62 (15) |
O23—Na2—O11viii | 145.71 (9) | O21—P2—O23 | 107.34 (15) |
O21—Na2—O11ix | 70.36 (11) | O24—P2—O22 | 109.88 (15) |
O21vi—Na2—O11ix | 115.83 (18) | O21—P2—O22 | 107.94 (14) |
O21v—Na2—O11ix | 98.43 (14) | O23—P2—O22 | 106.81 (14) |
Symmetry codes: (i) x, y, z−1; (ii) −x+1, −y, −z+1; (iii) −x+1, y, −z+3/2; (iv) x, −y, z−3/2; (v) x, −y, z−1/2; (vi) −x, y, −z+3/2; (vii) −x, −y, −z+2; (viii) −x+1/2, y−1/2, −z+3/2; (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; (xii) x−1/2, −y+1/2, z−1/2; (xiii) −x+1/2, −y+1/2, −z+2; (xiv) −x+1, −y, −z. |
M1 = Mn/Na, M2 = Mn/In, q = formal oxidation number, sof(i) = site-occupation factor, Q(i) = calculated charges, CN = coordination number, ECoN = number of effective coordination, dar = arithmetic average distance to oxygen atoms and dmed = weighted average distance to oxygen atoms. |
Cation | q.sof(i) | Q(i) | V(i).sof(i) | CN(i) | ECoN(i) | daverage | dmed |
Na1 | 0.50 | 0.50 | 0.542 | 7 | 5.56 | 2.550 | 2.428 |
Na2 | 0.77 | 0.75 | 0.716 | 8 | 6.70 | 2.738 | 2.653 |
M1 | 1.54 | 1.56 | 1.421 | 6 | 6.00 | 2.329 | 2.330 |
M2 | 2.84 | 2.84 | 2.696 | 6 | 5.87 | 2.150 | 2.141 |
P1 | 5.00 | 4.92 | 4.873 | 4 | 4.00 | 1.544 | 1.544 |
P2 | 5.00 | 5.05 | 4.844 | 4 | 3.98 | 1.546 | 1.545 |
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