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The single crystal of sodium manganese arsenate (1.72/3.28/12), Na1.72Mn3.28(AsO4)3, used for analysis was prepared by solid-state reaction at 1073 K. The compound crystallizes in the monoclinic system in space group C2/c. The structure consists of a complex network of edge-sharing MnO6 octahedral chains, linked together by AsO4 tetrahedra, forming two distinct channels, one containing Na+ cations and the other occupied statistically by Mn+ and Na+ cations.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010200882X/br1372sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010200882X/br1372Isup2.hkl
Contains datablock I

Comment top

The crystal structure of Na1.72Mn3.28(AsO4)3 is isostructural with the compounds X1X2M1M22(PO4)3 (Moore, 1971; Yakubovitch et al., 1994) of the alluaudite structure type. It can be described by an Mn3(AsO4)3 framework built up by a complex arrangement of distorted MnO6 octahedra and AsO4 tetrahedra. A projection of the structure showing the displacement ellipsoids is presented in Fig. 1. The Mn1O6 and Mn3O6 octahedra are grouped into chains with the sequence (Mn1–Mn3–Mn3)n running along the [010] direction through shared edges. In each chain, repetition of the Mn1O6 and Mn3O6 octahedra are ensured by c-glide and inversions centers, respectively. The infinite chains of Mn1O6 and Mn3O6 polyhedra are linked together by As1O4 and As2O4 tetrahedra. As2O4 tetrahedra always connect two chains and thus two of its O atoms belong of the same chain (Fig. 2a). The As1O4 tetrahedron shares its four oxygen corners with four different MnO6 octahedra belonging to three chains, two from the same chain and two from two different chains (Fig. 2 b).

In the present structure, the Mn1O6 and Mn3O6 octahedra which form the chains are distorted, with dav(Mn1—O) = 2.236 (5) Å and dav(Mn3—O) = 2.092 (2) Å. The cis O—Mn1—O angles range from 71.35 to 117.89°, whereas the O—Mn3—O angles range from 77.39 to 109.63°. The As atoms are surrounded by four O atoms, with mean As1—O and As2—O distances of 1.692 and 1.691 Å, respectively. Mn1 and Mn3 have different oxidation states since they have different bond lengths. A bond-valence calculation (Brown & Altermatt, 1985), based on parameters for Mn2+—O, gives a bond-valence sum of 1.80 for Mn1 and 2.69 for Mn3, which can be attributed to mixed-valence MnII/III. This gives an average of 2.40. For electroneutrality, the Mn2 oxidation state should be 0.89 and the bond-valence calculation for this tetracoordinated atom gives 0.88. Since the difference between the shortest and longest Mn3—O bond is 0.203 Å, the environment of this atom is distorted. A UV–visible spectoscopic study of this compound will probably reveal a Jahn–Teller effect for the Mn3 atom.

This arrangement of polyhedra generates two sets of channels parallel to the c axis and located at (1/2,0,z) and (0,0,z) respectively. Na+ and Mn22+ cations are located in these channels (Fig. 3).

The title structure is closely related to the alluaudite structure type. In Na1.72 Mn3.28(AsO4)3, the X2 site at (0,0,0) is empty, instead a site in the tunnel at (0,0,z) shifted from the X2 site by ±0.25 along z is occupied by Na1, which is similar to that observed in NaCo3(PO4)(HPO4)2 (Lii & Shih, 1994), NaCo3(AsO4)(HAsO4)2 (Lii & Shih, 1994), NaMn3(PO4)(HPO4)2 (Leroux et al., 1995), NaFe3.67(PO4)3 (Korzenski et al., 1998), Cu2Mg3(PO4)3 (Wraner et al., 1993) and Cu1.35Fe(PO4)3 (Wraner et al., 1993), whereas the X1 site at (1/2,0,0) contains the Mn2 and Na2 ions. Mn2 (site-occupation factor = 0.28) is located in a rectangular, slightly distorted, environment of two O atoms at distances of 2.340 (10) Å, with two others at distances of 2.360 (7) Å. The four corners of Mn2O4 are vertex-sharing to the Mn1O6 and Mn3O6 octahedra, which is similar to FeO4 in the structure of NaFe3.67(PO4)3 (Korzenski et al., 1998). The Na2 atoms (site-occupation factor = 0.72) is coordinated by four O atoms at a shorter distances [2.340 Å (× 2) and 2.360 Å (× 2)] and two O atoms at a longer distance (2.600 Å)

Experimental top

Single crystals of Na1.72 Mn3.28(AsO4)3 were prepared by a conventional solid-state reaction. NH4H2AsO4, MnO and Na2CO3 in the 3:2:1 ratio were ground together under acetone in an agate mortar. The mixture was heated in a porcelain crucible at 673 K for 4 h, cooled to room temperature, reground, and heated at 1073 K for 24 h, then cooled slowly to room temperature at 5 K h-1. The product was washed with hot water. Brown parallelepipedic crystals of the title compound were extracted. Qualitative analysis by electron microscope probe revealed them to contain Na, As and Mn atoms.

Refinement top

Direct methods were used to locate the metal atoms, and the remaining atoms were found from successive Fourier difference maps.

Computing details top

Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. A view of a sheet of the anionic framework of Na1.72Mn3.28(AsO4)3, shown with with 50% probability displacement ellipsoids
[Figure 2] Fig. 2. (a) A view showing the association mode between As2O4 tetrahedra and MnO6 octahedra. (b) A view showing the association mode between As1O4 tetrahedra and MnO6 octahedra.
[Figure 3] Fig. 3. Projection of the structure of Na1.7Mn3.3(AsO4)3 along the [001] direction.
sodium manganese arsenate(1.72/3.28/12) top
Crystal data top
Na1.72Mn3.28(AsO4)3F(000) = 1183.7
Mr = 636.49Dx = 4.331 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 25 reflections
a = 12.1975 (10) Åθ = 10.2–13.8°
b = 12.9531 (10) ŵ = 14.41 mm1
c = 6.754 (2) ÅT = 293 K
β = 113.85 (4)°Parallelepiped, brown
V = 976.1 (3) Å30.04 × 0.02 × 0.01 mm
Z = 4
Data collection top
Enraf-Nonius CAD-4
diffractometer
657 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.048
Graphite monochromatorθmax = 27.0°, θmin = 2.4°
ω/2θ scansh = 1514
Absorption correction: empirical (using intensity measurements)
(North et al., 1968)
k = 016
Tmin = 0.805, Tmax = 0.863l = 08
1159 measured reflections2 standard reflections every 120 min
1069 independent reflections intensity decay: 0.4%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.051 w = 1/[σ2(Fo2) + (0.0631P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.141(Δ/σ)max < 0.001
S = 1.01Δρmax = 1.43 e Å3
1069 reflectionsΔρmin = 1.53 e Å3
97 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.0009 (2)
Crystal data top
Na1.72Mn3.28(AsO4)3V = 976.1 (3) Å3
Mr = 636.49Z = 4
Monoclinic, C2/cMo Kα radiation
a = 12.1975 (10) ŵ = 14.41 mm1
b = 12.9531 (10) ÅT = 293 K
c = 6.754 (2) Å0.04 × 0.02 × 0.01 mm
β = 113.85 (4)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
657 reflections with I > 2σ(I)
Absorption correction: empirical (using intensity measurements)
(North et al., 1968)
Rint = 0.048
Tmin = 0.805, Tmax = 0.8632 standard reflections every 120 min
1159 measured reflections intensity decay: 0.4%
1069 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.05197 parameters
wR(F2) = 0.1411 restraint
S = 1.01Δρmax = 1.43 e Å3
1069 reflectionsΔρmin = 1.53 e Å3
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
xyzUiso*/UeqOcc. (<1)
As10.26553 (11)0.39072 (10)0.37208 (19)0.0130 (4)
As20.50000.21371 (14)0.25000.0137 (5)
Mn10.50000.2313 (2)0.25000.0154 (6)
Mn30.21981 (18)0.15604 (17)0.1346 (3)0.0206 (5)
Na10.50000.5112 (7)0.75000.0286 (19)
Mn20.50000.00000.00000.031 (2)0.28 (3)
Na20.50000.00000.00000.031 (2)0.72 (3)
O10.1193 (7)0.4051 (7)0.3111 (13)0.0166 (18)
O20.4555 (8)0.2890 (7)0.0250 (12)0.0154 (18)
O30.3383 (8)0.5049 (7)0.3914 (14)0.022 (2)
O40.3378 (8)0.3313 (7)0.6133 (14)0.020 (2)
O50.2791 (8)0.3175 (8)0.1736 (15)0.024 (2)
O60.3957 (10)0.1303 (8)0.2570 (18)0.037 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
As10.0104 (6)0.0155 (7)0.0104 (6)0.0007 (5)0.0015 (4)0.0026 (5)
As20.0216 (10)0.0083 (9)0.0076 (8)0.0000.0021 (7)0.000
Mn10.0145 (13)0.0122 (13)0.0222 (14)0.0000.0103 (11)0.000
Mn30.0200 (11)0.0228 (12)0.0179 (11)0.0035 (9)0.0064 (8)0.0000 (8)
Na10.018 (4)0.046 (5)0.019 (4)0.0000.005 (3)0.000
Mn20.043 (4)0.014 (3)0.019 (3)0.003 (3)0.004 (2)0.000 (2)
Na20.043 (4)0.014 (3)0.019 (3)0.003 (3)0.004 (2)0.000 (2)
O10.008 (4)0.020 (5)0.020 (4)0.001 (4)0.003 (3)0.000 (4)
O20.015 (4)0.021 (5)0.009 (4)0.002 (4)0.004 (3)0.006 (4)
O30.019 (4)0.021 (5)0.022 (4)0.006 (4)0.006 (4)0.004 (4)
O40.027 (5)0.018 (5)0.013 (4)0.009 (4)0.007 (4)0.003 (4)
O50.025 (5)0.032 (6)0.018 (4)0.001 (4)0.012 (4)0.001 (4)
O60.047 (7)0.020 (6)0.039 (6)0.002 (5)0.012 (5)0.005 (5)
Geometric parameters (Å, º) top
As1—O11.671 (8)Mn3—O52.193 (11)
As1—O41.692 (9)Na1—O32.429 (9)
As1—O31.703 (9)Na1—O3viii2.429 (9)
As1—O51.704 (9)Na1—O3ix2.524 (9)
As2—O61.684 (11)Na1—O3x2.524 (9)
As2—O6i1.684 (11)Na1—O2x2.939 (12)
As2—O2i1.699 (8)Na1—O2ix2.939 (12)
As2—O21.699 (8)Na1—O42.953 (12)
Mn1—O1ii2.218 (9)Na1—O4viii2.953 (12)
Mn1—O1iii2.218 (9)Mn2—O6xi2.340 (11)
Mn1—O4i2.230 (9)Mn2—O6i2.340 (11)
Mn1—O4iv2.230 (9)Mn2—O1ii2.360 (8)
Mn1—O22.262 (9)Mn2—O1xii2.360 (8)
Mn1—O2v2.262 (9)Na2—O6xi2.340 (11)
Mn3—O61.990 (12)Na2—O6i2.340 (11)
Mn3—O3vi2.065 (9)Na2—O1ii2.360 (8)
Mn3—O2ii2.093 (9)Na2—O1xii2.360 (8)
Mn3—O4vii2.094 (9)Na2—O1vi2.600 (8)
Mn3—O5ii2.115 (9)Na2—O1iii2.600 (8)
O1—As1—O4112.1 (4)O2ii—Mn3—O4vii77.5 (3)
O1—As1—O3113.2 (4)O6—Mn3—O5ii90.1 (4)
O4—As1—O3105.6 (5)O3vi—Mn3—O5ii102.0 (4)
O1—As1—O5107.5 (4)O2ii—Mn3—O5ii81.4 (3)
O4—As1—O5109.0 (4)O4vii—Mn3—O5ii157.7 (4)
O3—As1—O5109.3 (4)O6—Mn3—O582.1 (4)
O6—As2—O6i100.2 (8)O3vi—Mn3—O5177.5 (4)
O6—As2—O2i108.3 (5)O2ii—Mn3—O587.5 (4)
O6i—As2—O2i114.9 (5)O4vii—Mn3—O591.7 (4)
O6—As2—O2114.9 (5)O5ii—Mn3—O580.3 (4)
O6i—As2—O2108.3 (5)O6xi—Mn2—O6i180.0
O2i—As2—O2110.0 (6)O6xi—Mn2—O1ii77.7 (3)
O1ii—Mn1—O1iii74.5 (4)O6i—Mn2—O1ii102.3 (3)
O1ii—Mn1—O4i161.0 (3)O6xi—Mn2—O1xii102.3 (3)
O1iii—Mn1—O4i88.9 (3)O6i—Mn2—O1xii77.7 (3)
O1ii—Mn1—O4iv88.9 (3)O1ii—Mn2—O1xii180.0
O1iii—Mn1—O4iv161.0 (3)O6xi—Na2—O6i180.0 (7)
O4i—Mn1—O4iv108.9 (5)O6xi—Na2—O1ii77.7 (3)
O1ii—Mn1—O293.4 (3)O6i—Na2—O1ii102.3 (3)
O1iii—Mn1—O2117.9 (3)O6xi—Na2—O1xii102.3 (3)
O4i—Mn1—O286.3 (3)O6i—Na2—O1xii77.7 (3)
O4iv—Mn1—O271.4 (3)O1ii—Na2—O1xii180.0
O1ii—Mn1—O2v117.9 (3)O6xi—Na2—O1vi75.5 (3)
O1iii—Mn1—O2v93.4 (3)O6i—Na2—O1vi104.5 (3)
O4i—Mn1—O2v71.4 (3)O1ii—Na2—O1vi114.7 (3)
O4iv—Mn1—O2v86.3 (3)O1xii—Na2—O1vi65.3 (3)
O2—Mn1—O2v141.4 (5)O6xi—Na2—O1iii104.5 (3)
O6—Mn3—O3vi98.7 (4)O6i—Na2—O1iii75.5 (3)
O6—Mn3—O2ii167.5 (4)O1ii—Na2—O1iii65.3 (3)
O3vi—Mn3—O2ii92.0 (3)O1xii—Na2—O1iii114.7 (3)
O6—Mn3—O4vii109.6 (4)O1vi—Na2—O1iii180.0
O3vi—Mn3—O4vii85.8 (4)
Symmetry codes: (i) x+1, y, z+1/2; (ii) x+1/2, y+1/2, z; (iii) x+1/2, y+1/2, z1/2; (iv) x, y, z1; (v) x+1, y, z1/2; (vi) x+1/2, y1/2, z+1/2; (vii) x+1/2, y+1/2, z+1; (viii) x+1, y, z+3/2; (ix) x, y+1, z+1/2; (x) x+1, y+1, z+1; (xi) x, y, z1/2; (xii) x+1/2, y1/2, z.

Experimental details

Crystal data
Chemical formulaNa1.72Mn3.28(AsO4)3
Mr636.49
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)12.1975 (10), 12.9531 (10), 6.754 (2)
β (°) 113.85 (4)
V3)976.1 (3)
Z4
Radiation typeMo Kα
µ (mm1)14.41
Crystal size (mm)0.04 × 0.02 × 0.01
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionEmpirical (using intensity measurements)
(North et al., 1968)
Tmin, Tmax0.805, 0.863
No. of measured, independent and
observed [I > 2σ(I)] reflections
1159, 1069, 657
Rint0.048
(sin θ/λ)max1)0.638
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.051, 0.141, 1.01
No. of reflections1069
No. of parameters97
No. of restraints1
Δρmax, Δρmin (e Å3)1.43, 1.53

Computer programs: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992), CAD-4 EXPRESS, MolEN (Fair, 1990), SHELXS86 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1998).

Selected bond lengths (Å) top
As1—O11.671 (8)Mn3—O4iv2.094 (9)
As1—O41.692 (9)Mn3—O5i2.115 (9)
As1—O31.703 (9)Mn3—O52.193 (11)
As1—O51.704 (9)Na1—O32.429 (9)
As2—O61.684 (11)Na1—O3v2.524 (9)
As2—O21.699 (8)Na1—O2vi2.939 (12)
Mn1—O1i2.218 (9)Na1—O42.953 (12)
Mn1—O4ii2.230 (9)Mn2—O6vii2.340 (11)
Mn1—O22.262 (9)Mn2—O1i2.360 (8)
Mn3—O61.990 (12)Na2—O6ii2.340 (11)
Mn3—O3iii2.065 (9)Na2—O1i2.360 (8)
Mn3—O2i2.093 (9)Na2—O1iii2.600 (8)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x+1, y, z+1/2; (iii) x+1/2, y1/2, z+1/2; (iv) x+1/2, y+1/2, z+1; (v) x, y+1, z+1/2; (vi) x+1, y+1, z+1; (vii) x, y, z1/2.
 

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