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Acta Cryst. (2013). E69, i40    [ doi:10.1107/S1600536813016504 ]

A new mixed-valence lead(II) mangan­ese(II/III) phosphate(V): PbMnII2MnIII(PO4)3

G. Alhakmi, A. Assani, M. Saadi and L. El Ammari

Abstract top

The title compound, lead trimanganese tris(orthophosphate), has been synthesized by hydro­thermal methods. In this structure, only two O atoms are in general positions and all others atoms are in the special positions of the Imma space group. Indeed, the atoms in the Wyckoff positions are namely: Pb1 and P1 on 4e (mm2); Mn1 on 4b (2/m); Mn2 and P2 on 8g (2); O1 on 8h (m); O2 on 8i (m). The crystal structure can be viewed as a three-dimensional network of corner- and edge-sharing PO4 tetra­hedra and MnO6 octa­hedra, building two types of chains running along the b axis. The first is an infinite linear chain, formed by alternating MnIIIO6 octa­hedra and PO4 tetra­hedra which share one vertex. The second chain is built up from two adjacent edge-sharing octa­hedra (MnII2O10 dimers) whose ends are linked to two PO4 tetra­hedra by a common edge. These chains are linked together by common vertices of polyhedra in such a way as to form porous layers parallel to (001). These sheets are bonded by the first linear chains, leading to the appearance of two types of tunnels, one propagating along the a axis and the other along b. The PbII ions are located within the inter­sections of the tunnels with eight neighbouring O atoms in form of a trigonal prism that is capped by two O atoms on one side. The three-dimensional framework of this structure is compared with similar phosphates such as Ag2Co3(HPO4)(PO4)2 and Ag2Ni3(HPO4)(PO4)2.

Comment top

In a previous hydrothermal investigation of the system A2O—MO—P2O5, we have succeeded to synthesize and structurally characterize new phosphate like Ag2M3(HPO4)(PO4)2 (M = Co, Ni) which crystallizes in orthorhombic system with Ima2 space group (Assani et al., 2011a, 2011b). The structure of this compound is an open frameworks such as that observed in the alluaudite. On the basis of crystallographic considerations, the later phosphates structure represents similarities with the well known alluaudite structure. Accordingly, both structures can be represented by the general formula A(1) A(2)M(1)M(2)2(PO4)3 as it has been established by Moore & Ito, 1979, in the case of alluaudite related compounds. This model is written according to decreasing size of the discrete sites. Mainly, the A sites can be occupied by either mono- or divalent medium-sized cations while the M cationic site corresponds to an octahedral environment generally occupied by the transition metal cations. This fact, particularly in the case of the alluaudite structure, has offered a great field of application as positive electrode in the lithium and sodium batteries (Trad et al., 2010).

In accordance with the forefront of our research, a focus of investigation is associated with the mixed cation orthophosphates belonging to the above-mentioned compounds. Hence, by means of the hydrothermal method, we have recently synthesized and structurally characterized numerous phosphates corresponding to the general formula A(1) A(2)M(1)2M(2)(PO4)3 (Assani et al., 2011c). The present paper is devoted to one of them, namely, PbMn2+2Mn3+(PO4)3, with manganese mixed valence, rarely encountered in the literature (Adam et al., 2009).

A partial three-dimensional plot of the crystal structure of the title compound is represented in Fig. 1, illustrating the connection of the metal-oxygen polyhedra. All atoms of this structure are in special positions, except two oxygen atoms (O3,O4) in general position of the Imma space group. The crystal structure network consists of single phosphate PO4 tetrahedron linked to MnO6 octahedra, building two types of chains running along the b axis. The first chain is formed by an alternating MnIIIO6 octahedron and PO4 tetrahedron which share one vertex. The second chain is built up from two adjacent edge sharing octahedra (MnII2O10, dimers) whose ends are linked to two PO4 tetrahedra by a common edge. These two types of chains are linked together by common vertex of plyhedra to form porous sheets parallel to the (0 0 1) plane. The three dimensional framework delimits two types of tunnels parallel to a and b directions where the lead atoms are located as shown in Fig.2. Each lead cation is surrounded by 8 oxygenes.

Bond valence sum calculationlead(II) manganese(II/III) triphosphate(V): PbMn3(PO4)3s (Brown & Altermatt, 1985) for Pb12+, Mn13+, Mn22+, P15+ and P25+ ions are as expected, viz. 1.796, 3.042, 1.975, 5.014 and 4.843 valence units, respectively. The values of the bond valence sums calculated for all oxygen atoms are as expected in the range of 1.79 – 2.04 valence units. The three-dimensional framework of this structure is compared with some phosphates like Ag2M3(HPO4)(PO4)2 with M = Ni or Co, wherein the two Ag+ cations in the tunnels are replaced by Pb2+.

Related literature top

For compounds with related structures see: Assani et al. (2011a,b,c); Moore & Ito (1979). For applications of related compounds, see: Trad et al. (2010). For compounds with mixed-valence manganese(II/III) lead(II) triphosphates(V), see: Adam et al. (2009). For bond-valence analysis, see: Brown & Altermatt (1985).

Experimental top

The crystal of the title compound is isolated from the hydrothermal treatment of the reaction mixture of lead, manganese and phosphate precursors in a proportion corresponding to the molar ratio Pb:Mn:P = 1: 3:3. The hydrothermal reaction was conducted in a 23 ml Teflon-lined autoclave, filled to 50% with distilled water and under autogeneous pressure at 483 K for five days. After being filtered off, washed with deionized water and air dried, the reaction product consists of a brown sheet shaped crystals corresponding to the title compound besides a light brown powder.

Refinement top

The highest peak and the deepest hole in the final Fourier map are at 0.78 Å and 0.76 Å, respectively, from Pb1. The not significant bonds and angles were removed from the CIF file.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. A partial three-dimensional plot of the crystal structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes:(i) -x, y + 1/2, -z; (ii) -x, -y, -z; (iii) x, -y + 1/2, z; (iv) -x, -y, -z + 1; (v) -x - 1, -y, -z; (vi) x + 1, y, z; (vii) -x, -y + 1, -z + 1; (viii) x + 1, -y + 1/2, z + 1; (ix) x + 1, y + 1, z; (x) x, -y - 1/2, z; (xi) x - 1, y - 1, z; (xii) -x, y - 1/2, -z + 1; (xiii) -x - 1, y + 1/2, -z;
[Figure 2] Fig. 2. Polyhedral representation of PbMn3(PO4)3 showing tunnels running along the a and b directions.
Lead(II) manganese(II/III) phosphate(V) top
Crystal data top
PbMn3(PO4)3F(000) = 1192
Mr = 656.92Dx = 4.596 Mg m3
Orthorhombic, ImmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2b 2Cell parameters from 787 reflections
a = 10.2327 (8) Åθ = 2.9–30.5°
b = 13.9389 (9) ŵ = 22.15 mm1
c = 6.6567 (4) ÅT = 296 K
V = 949.46 (11) Å3Sheet, brown
Z = 40.36 × 0.23 × 0.10 mm
Data collection top
Bruker X8 APEX
787 independent reflections
Radiation source: fine-focus sealed tube771 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.028
ϕ and ω scansθmax = 30.5°, θmin = 2.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 1414
Tmin = 0.046, Tmax = 0.215k = 1919
4704 measured reflectionsl = 99
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.016Secondary atom site location: difference Fourier map
wR(F2) = 0.040 w = 1/[σ2(Fo2) + (0.0205P)2 + 2.635P]
where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max < 0.001
787 reflectionsΔρmax = 2.54 e Å3
53 parametersΔρmin = 0.98 e Å3
Crystal data top
PbMn3(PO4)3V = 949.46 (11) Å3
Mr = 656.92Z = 4
Orthorhombic, ImmaMo Kα radiation
a = 10.2327 (8) ŵ = 22.15 mm1
b = 13.9389 (9) ÅT = 296 K
c = 6.6567 (4) Å0.36 × 0.23 × 0.10 mm
Data collection top
Bruker X8 APEX
787 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
771 reflections with I > 2σ(I)
Tmin = 0.046, Tmax = 0.215Rint = 0.028
4704 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01653 parameters
wR(F2) = 0.0400 restraints
S = 1.11Δρmax = 2.54 e Å3
787 reflectionsΔρmin = 0.98 e Å3
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
Pb10.00000.25000.11391 (3)0.01308 (7)
Mn10.00000.00000.50000.00488 (14)
Mn20.25000.36754 (4)0.25000.00774 (12)
P10.00000.25000.40554 (17)0.0044 (2)
P20.25000.57316 (6)0.25000.00507 (17)
O10.00000.16010 (18)0.5362 (4)0.0086 (5)
O20.1182 (3)0.25000.2619 (4)0.0084 (5)
O30.2066 (2)0.63321 (13)0.0719 (3)0.0101 (4)
O40.36271 (18)0.50018 (12)0.1977 (3)0.0078 (3)
Atomic displacement parameters (Å2) top
Pb10.01879 (13)0.01275 (10)0.00770 (10)0.0000.0000.000
Mn10.0038 (3)0.0069 (3)0.0040 (3)0.0000.0000.0000 (2)
Mn20.0093 (3)0.0054 (2)0.0085 (2)0.0000.00019 (19)0.000
P10.0044 (6)0.0045 (5)0.0044 (5)0.0000.0000.000
P20.0056 (4)0.0047 (3)0.0049 (4)0.0000.0007 (3)0.000
O10.0092 (13)0.0067 (10)0.0100 (11)0.0000.0000.0033 (9)
O20.0069 (12)0.0086 (10)0.0098 (11)0.0000.0036 (9)0.000
O30.0123 (10)0.0118 (8)0.0061 (7)0.0036 (7)0.0014 (7)0.0030 (6)
O40.0070 (9)0.0078 (7)0.0086 (8)0.0002 (6)0.0023 (7)0.0005 (6)
Geometric parameters (Å, º) top
Pb1—O1i2.645 (3)Mn2—O3iv2.1881 (18)
Pb1—O1ii2.645 (3)Mn2—O3xii2.1881 (18)
Pb1—O3iii2.683 (2)Mn2—O4xiii2.2067 (18)
Pb1—O3iv2.683 (2)Mn2—O42.2067 (18)
Pb1—O3v2.683 (2)Mn2—P22.8660 (10)
Pb1—O3vi2.683 (2)P1—O2xiv1.542 (3)
Mn1—O4vii1.9249 (18)P1—O21.542 (3)
Mn1—O4viii1.9249 (18)P1—O1xiv1.525 (3)
Mn1—O4ix1.9249 (18)P1—O11.525 (3)
Mn1—O4x1.9249 (18)P2—O3xiii1.5180 (19)
Mn1—O12.245 (3)P2—O31.5180 (19)
Mn1—O1xi2.245 (3)P2—O4xiii1.5767 (19)
Mn2—O22.1237 (18)P2—O41.5767 (19)
Mn2—O2x2.1237 (18)
O1i—Pb1—O1ii56.57 (11)O1—Mn1—O1xi180.0
O1i—Pb1—O3iii78.72 (5)O2—Mn2—O2x79.02 (12)
O1ii—Pb1—O3iii112.30 (5)O2—Mn2—O3iv84.48 (8)
O1i—Pb1—O3iv112.30 (5)O2x—Mn2—O3iv95.10 (9)
O1ii—Pb1—O3iv78.72 (5)O2—Mn2—O3xii95.10 (9)
O3iii—Pb1—O3iv168.02 (8)O2x—Mn2—O3xii84.48 (8)
O1i—Pb1—O3v112.30 (5)O3iv—Mn2—O3xii179.45 (10)
O1ii—Pb1—O3v78.72 (5)O2—Mn2—O4xiii107.97 (8)
O3iii—Pb1—O3v74.73 (9)O2x—Mn2—O4xiii169.80 (8)
O3iv—Pb1—O3v103.98 (9)O3iv—Mn2—O4xiii93.00 (7)
O1i—Pb1—O3vi78.72 (5)O3xii—Mn2—O4xiii87.46 (7)
O1ii—Pb1—O3vi112.30 (5)O2—Mn2—O4169.80 (8)
O3iii—Pb1—O3vi103.98 (9)O2x—Mn2—O4107.97 (8)
O3iv—Pb1—O3vi74.73 (9)O3iv—Mn2—O487.46 (7)
O3v—Pb1—O3vi168.02 (8)O3xii—Mn2—O493.00 (7)
O4vii—Mn1—O4viii180.0O4xiii—Mn2—O466.18 (10)
O4vii—Mn1—O4ix93.75 (11)O2xiv—P1—O2103.3 (2)
O4viii—Mn1—O4ix86.25 (11)O2xiv—P1—O1xiv110.72 (7)
O4vii—Mn1—O4x86.25 (11)O2—P1—O1xiv110.72 (7)
O4viii—Mn1—O4x93.75 (11)O2xiv—P1—O1110.72 (7)
O4ix—Mn1—O4x180.0O2—P1—O1110.72 (7)
O4vii—Mn1—O185.71 (7)O1xiv—P1—O1110.5 (2)
O4viii—Mn1—O194.29 (7)O3xiii—P2—O3113.08 (15)
O4ix—Mn1—O185.71 (7)O3xiii—P2—O4xiii113.41 (10)
O4x—Mn1—O194.29 (7)O3—P2—O4xiii108.31 (11)
O4vii—Mn1—O1xi94.29 (7)O3xiii—P2—O4108.31 (11)
O4viii—Mn1—O1xi85.71 (7)O3—P2—O4113.41 (10)
O4ix—Mn1—O1xi94.29 (7)O4xiii—P2—O499.65 (13)
O4x—Mn1—O1xi85.71 (7)
Symmetry codes: (i) x, y, z1; (ii) x, y+1/2, z1; (iii) x, y1/2, z; (iv) x, y+1, z; (v) x, y+1, z; (vi) x, y1/2, z; (vii) x+1/2, y1/2, z+1/2; (viii) x1/2, y+1/2, z+1/2; (ix) x1/2, y1/2, z+1/2; (x) x+1/2, y+1/2, z+1/2; (xi) x, y, z+1; (xii) x+1/2, y+1, z+1/2; (xiii) x+1/2, y, z+1/2; (xiv) x, y+1/2, z.

Experimental details

Crystal data
Chemical formulaPbMn3(PO4)3
Crystal system, space groupOrthorhombic, Imma
Temperature (K)296
a, b, c (Å)10.2327 (8), 13.9389 (9), 6.6567 (4)
V3)949.46 (11)
Radiation typeMo Kα
µ (mm1)22.15
Crystal size (mm)0.36 × 0.23 × 0.10
Data collection
DiffractometerBruker X8 APEX
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.046, 0.215
No. of measured, independent and
observed [I > 2σ(I)] reflections
4704, 787, 771
(sin θ/λ)max1)0.713
R[F2 > 2σ(F2)], wR(F2), S 0.016, 0.040, 1.11
No. of reflections787
No. of parameters53
Δρmax, Δρmin (e Å3)2.54, 0.98

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006), publCIF (Westrip, 2010).

Acknowledgements top

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.