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The title compound, strontium trimanganese tris­(ortho­phosphate), was synthesized under hydro­thermal conditions. Its structure is isotypic to that of the lead analogue PbMnII2MnIII(PO4)3. Two O atoms are in general positions, whereas all others atoms are in special positions. The Sr and one P atom exhibit mm2 symmetry, the MnII atom 2/m symmetry, the MnIII atom and the other P atom .2. symmetry and two O atoms are located on mirror planes. The three-dimensional network of the crystal structure is made up of two types of chains running parallel to [010]. One chain is linear and is composed of alternating MnIIIO6 octa­hedra and PO4 tetra­hedra sharing vertices; the other chain has a zigzag arrangement and is built up from two edge-sharing MnIIO6 octa­hedra connected to PO4 tetra­hedra by edges and vertices. The two types of chains are linked through PO4 tetra­hedra, leading to the formation of channels parallel to [100] and [010] in which the SrII ions are located. They are surrounded by eight O atoms in the form of a slightly distorted bicapped trigonal prism.

Supporting information


Crystallographic Information File (CIF)
Contains datablock I


Structure factor file (CIF format)
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](P-O) = 0.002 Å
  • R factor = 0.025
  • wR factor = 0.066
  • Data-to-parameter ratio = 18.7

checkCIF/PLATON results

No syntax errors found

Alert level C PLAT975_ALERT_2_C Positive Residual Density at 0.48A from O1 . 0.48 eA-3 PLAT975_ALERT_2_C Positive Residual Density at 1.02A from O3 . 0.41 eA-3
Alert level G PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension . 3 PLAT005_ALERT_5_G No _iucr_refine_instructions_details in the CIF ? Do ! PLAT790_ALERT_4_G Centre of Gravity not Within Unit Cell: Resd. # 2 Sr PLAT793_ALERT_4_G The Model has Chirality at P2 (Verify) .... S PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L= 0.600 3
0 ALERT level A = Most likely a serious problem - resolve or explain 0 ALERT level B = A potentially serious problem, consider carefully 2 ALERT level C = Check. Ensure it is not caused by an omission or oversight 5 ALERT level G = General information/check it is not something unexpected 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 3 ALERT type 4 Improvement, methodology, query or suggestion 2 ALERT type 5 Informative message, check

Comment top

Hydrothermal studies in the systems A2O–MO–P2O5 and M'O–MO–P2O5 led to new phosphates with framework structures closely related to that of the alluaudite [(Na,Ca)MnII(FeIII,MnIII,FeIIMg)2(PO4)3] structure type. For instance, the phosphates Ag2M3(HPO4)(PO4)2 (M = Co, Ni) (Assani et al., 2011a,b and PbMnII2MnIII(PO4)3 (Alhakmi et al., 2013) were prepared this way. Their compositions can be represented by the general formula (A1)(A2)(M1)(M2)2(PO4)3 as introduced by Moore & Ito (1979) for alluaudite-related compounds. In this nomenclature the order of the cations A and M is related to the 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 sites correspond to an octahedral environment generally occupied by transition metal cations. In the case of alluaudite-type compounds, a great field of applications such as positive electrodes in lithium and sodium batteries (Trad et al., 2010) has been established. Our focus of investigation is associated with mixed-cations orthophosphates that are related to the above mentioned compounds. By means of the hydrothermal synthesis method, we have recently prepared and structurally characterized (A1)(A2)(M1)(M2)2(PO4)3 phosphates (Assani et al., 2011c). The present paper describes the synthesis and structural characterization of the mixed-valent MnII,III phosphate with composition SrMnII2MnIII(PO4)3. Such MnII,III systems are rather scarce (Adam et al., 2009). The structure of the title compound is isotypic to that of the lead analogue PbMnII2MnIII(PO4)3 (Alhakmi et al., 2013)

Except two oxygen atoms (O3, O4) in general positions, all other atoms are located on special positions of space group Imma. The connection of the metal-oxygen polyhedra, viz. SrO8 polyhedra, MnO6 octahedra and PO4 tetrahedra is shown in Fig. 1. The crystal structure consists of two isolated PO4 tetrahedra linked to two types of MnO6 octahedra, building two different chains running parallel to [010]. The first chain is formed by alternating MnIIIO6 octahedra and PO4 tetrahedra by sharing vertices. The second chain is built up from two adjacent edge-sharing octahedra (MnII2O10 dimers) that are further linked to two PO4 tetrahedra by a common edge. These two types of chains are linked together by common vertices of PO4 tetrahedra to form a porous three-dimensional framework that delimits two types of tunnels parallel to [100] and [010] where the SrII ions are located (Fig. 2). The coordination sphere of the alkaline earth metal ions is that of a bicapped trigonal prism.

Bond valence calculations (Brown & Altermatt, 1985) of SrMnII2MnIII(PO4)3 revealed bond valence sums for Sr1II+, Mn1III+, Mn2II+, P1V+ and P2V+ that are close to the expected values, viz. 1.81, 3.06, 1.98, 5.02 and 4.87 valence units (v.u.), respectively. The bond valence sums calculated for all O atoms are in the range of 1.79 – 2.04 v.u., thus confirming the validity of the structure model.

The framework of the title compound shows some resemblance to that of Ag2M3(HPO4)(PO4)2 phosphates (M = Ni, Co; Assani et al., 2011a,b), whereby the two AgI cations in the channels are replaced by SrII.

Related literature top

For the isotypic lead analogue, see: Alhakmi et al. (2013). For compounds with related structures, see: Adam et al. (2009); Assani et al. (2011a,b,c); Moore & Ito (1979). For applications of related compounds, see: Trad et al. (2010). For the by-product phase, see: Moore & Araki (1973). For bond-valence analysis, see: Brown & Altermatt (1985).

Experimental top

Crystals of the title compound were isolated from the hydrothermal treatment of a reaction mixture of strontium, manganese and phosphate precursors in a proportion corresponding to the molar ratio Sr: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 478 K for five days. After being filtered off, washed with deionized water and air dried, the reaction product consisted of brown sheet-shaped crystals corresponding to the title compound. Besides, parallelepipedic colourless crystals were present which were identified to be Mn5(HPO4)2(PO4)2.4H2O (Moore & Araki, 1973).

Refinement top

The highest and lowest remaining electron density peaks in the final Fourier map are 0.71 Å and 0.49 Å, respectively, away from O3 and P2.

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. The main building units of the crystal structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) x, -y + 1, -z; (ii) -x, y - 1/2, -z; (iii) x, y - 1/2, -z; (iv) -x, -y + 1, -z; (v) x, y, z - 1; (vi) -x, -y + 1/2, z - 1; (vii) -x, -y + 1/2, z; (viii) -x + 1/2, y - 1/2, z + 1/2; (ix) x - 1/2, -y + 1/2, -z + 1/2; (x) -x + 1/2, -y + 1/2, -z + 1/2; (xi) x - 1/2, y - 1/2, z + 1/2; (xii) -x, -y, -z + 1; (xiii) -x + 1/2, -y + 1, z + 1/2; (xiv) -x + 1/2, y, -z + 1/2.]
[Figure 2] Fig. 2. Polyhedral representation of SrMn3(PO4)3 with channels running parallel to [100].
Strontium trimanganese tris(orthophosphate) top
Crystal data top
SrMn3(PO4)3F(000) = 1016
Mr = 537.35Dx = 3.788 Mg m3
Orthorhombic, ImmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2b 2Cell parameters from 991 reflections
a = 10.2373 (10) Åθ = 2.9–33.3°
b = 13.8981 (15) ŵ = 10.14 mm1
c = 6.6230 (6) ÅT = 296 K
V = 942.31 (16) Å3Sheet, brown
Z = 40.28 × 0.15 × 0.12 mm
Data collection top
991 independent reflections
Radiation source: fine-focus sealed tube877 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.040
ϕ and ω scansθmax = 33.3°, θmin = 2.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 1515
Tmin = 0.164, Tmax = 0.376k = 2110
4726 measured reflectionsl = 910
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.025Secondary atom site location: difference Fourier map
wR(F2) = 0.066 w = 1/[σ2(Fo2) + (0.0389P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
991 reflectionsΔρmax = 0.83 e Å3
53 parametersΔρmin = 0.92 e Å3
Crystal data top
SrMn3(PO4)3V = 942.31 (16) Å3
Mr = 537.35Z = 4
Orthorhombic, ImmaMo Kα radiation
a = 10.2373 (10) ŵ = 10.14 mm1
b = 13.8981 (15) ÅT = 296 K
c = 6.6230 (6) Å0.28 × 0.15 × 0.12 mm
Data collection top
991 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
877 reflections with I > 2σ(I)
Tmin = 0.164, Tmax = 0.376Rint = 0.040
4726 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02553 parameters
wR(F2) = 0.0660 restraints
S = 1.04Δρmax = 0.83 e Å3
991 reflectionsΔρmin = 0.92 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 > 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
Sr10.00000.25000.10600 (6)0.00886 (11)
Mn10.00000.50000.50000.00446 (14)
Mn20.25000.36768 (4)0.25000.00742 (12)
P10.00000.25000.40707 (15)0.00402 (19)
P20.25000.57346 (6)0.25000.00591 (16)
O10.00000.16039 (16)0.5390 (3)0.0089 (4)
O20.1174 (2)0.25000.2602 (3)0.0080 (4)
O30.20437 (17)0.63359 (12)0.0726 (2)0.0101 (3)
O40.36220 (15)0.50005 (12)0.1971 (2)0.0079 (3)
Atomic displacement parameters (Å2) top
Sr10.01068 (19)0.0107 (2)0.00518 (18)0.0000.0000.000
Mn10.0042 (3)0.0064 (3)0.0027 (3)0.0000.0000.0000 (2)
Mn20.0095 (2)0.0054 (2)0.0073 (2)0.0000.00037 (15)0.000
P10.0052 (4)0.0042 (5)0.0027 (4)0.0000.0000.000
P20.0072 (3)0.0062 (4)0.0043 (3)0.0000.0006 (2)0.000
O10.0111 (10)0.0067 (10)0.0089 (9)0.0000.0000.0021 (8)
O20.0075 (10)0.0099 (10)0.0065 (10)0.0000.0031 (7)0.000
O30.0126 (7)0.0102 (8)0.0074 (7)0.0023 (6)0.0006 (6)0.0026 (6)
O40.0087 (7)0.0079 (7)0.0072 (7)0.0004 (6)0.0033 (5)0.0006 (5)
Geometric parameters (Å, º) top
Sr1—O3i2.6540 (17)Mn2—O22.1265 (15)
Sr1—O3ii2.6540 (17)Mn2—O2xiii2.1265 (15)
Sr1—O3iii2.6540 (17)Mn2—O3i2.1869 (16)
Sr1—O3iv2.6540 (17)Mn2—O3ix2.1869 (16)
Sr1—O1v2.660 (2)Mn2—O42.1969 (17)
Sr1—O1vi2.660 (2)Mn2—O4xi2.1969 (17)
Sr1—O22.707 (2)P1—O1vii1.522 (2)
Sr1—O2vii2.707 (2)P1—O11.522 (2)
Mn1—O4viii1.9219 (15)P1—O2vii1.546 (2)
Mn1—O4ix1.9219 (15)P1—O21.546 (2)
Mn1—O4x1.9219 (15)P2—O3xi1.5158 (16)
Mn1—O4xi1.9219 (15)P2—O31.5158 (16)
Mn1—O1xii2.244 (2)P2—O4xi1.5758 (17)
Mn1—O1vii2.244 (2)P2—O41.5758 (17)
O3i—Sr1—O3ii75.12 (8)O4ix—Mn1—O1xii94.51 (6)
O3i—Sr1—O3iii170.43 (7)O4x—Mn1—O1xii94.51 (6)
O3ii—Sr1—O3iii104.06 (8)O4xi—Mn1—O1xii85.49 (6)
O3i—Sr1—O3iv104.06 (8)O4viii—Mn1—O1vii94.51 (6)
O3ii—Sr1—O3iv170.43 (7)O4ix—Mn1—O1vii85.49 (6)
O3iii—Sr1—O3iv75.12 (8)O4x—Mn1—O1vii85.49 (6)
O3i—Sr1—O1v111.04 (5)O4xi—Mn1—O1vii94.51 (6)
O3ii—Sr1—O1v77.78 (4)O1xii—Mn1—O1vii180.0
O3iii—Sr1—O1v77.78 (4)O2—Mn2—O2xiii79.45 (9)
O3iv—Sr1—O1v111.04 (5)O2—Mn2—O3i83.60 (7)
O3i—Sr1—O1vi77.78 (4)O2xiii—Mn2—O3i95.69 (7)
O3ii—Sr1—O1vi111.04 (5)O2—Mn2—O3ix95.69 (7)
O3iii—Sr1—O1vi111.04 (5)O2xiii—Mn2—O3ix83.60 (7)
O3iv—Sr1—O1vi77.78 (4)O3i—Mn2—O3ix179.07 (9)
O1v—Sr1—O1vi55.83 (10)O2—Mn2—O4169.37 (7)
O3i—Sr1—O264.86 (5)O2xiii—Mn2—O4107.77 (6)
O3ii—Sr1—O264.86 (5)O3i—Mn2—O487.85 (6)
O3iii—Sr1—O2105.98 (5)O3ix—Mn2—O492.92 (6)
O3iv—Sr1—O2105.98 (5)O2—Mn2—O4xi107.77 (6)
O1v—Sr1—O2142.35 (4)O2xiii—Mn2—O4xi169.37 (7)
O1vi—Sr1—O2142.35 (4)O3i—Mn2—O4xi92.92 (6)
O3i—Sr1—O2vii105.98 (5)O3ix—Mn2—O4xi87.85 (6)
O3ii—Sr1—O2vii105.98 (5)O4—Mn2—O4xi66.27 (8)
O3iii—Sr1—O2vii64.86 (5)O1vii—P1—O1109.88 (18)
O3iv—Sr1—O2vii64.86 (5)O1vii—P1—O2vii111.19 (6)
O1v—Sr1—O2vii142.35 (4)O1—P1—O2vii111.19 (6)
O1vi—Sr1—O2vii142.35 (4)O1vii—P1—O2111.19 (6)
O2—Sr1—O2vii52.72 (9)O1—P1—O2111.19 (6)
O4viii—Mn1—O4ix180.0O2vii—P1—O2102.03 (17)
O4viii—Mn1—O4x85.55 (10)O3xi—P2—O3113.08 (14)
O4ix—Mn1—O4x94.45 (10)O3xi—P2—O4xi114.15 (9)
O4viii—Mn1—O4xi94.45 (10)O3—P2—O4xi107.75 (9)
O4ix—Mn1—O4xi85.55 (10)O3xi—P2—O4107.75 (9)
O4x—Mn1—O4xi180.0O3—P2—O4114.15 (9)
O4viii—Mn1—O1xii85.49 (6)O4xi—P2—O499.29 (12)
Symmetry codes: (i) x, y+1, z; (ii) x, y1/2, z; (iii) x, y1/2, z; (iv) x, y+1, z; (v) x, y, z1; (vi) x, y+1/2, z1; (vii) x, y+1/2, z; (viii) x1/2, y, z+1/2; (ix) x+1/2, y+1, z+1/2; (x) x1/2, y+1, z+1/2; (xi) x+1/2, y, z+1/2; (xii) x, y+1/2, z+1; (xiii) x+1/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaSrMn3(PO4)3
Crystal system, space groupOrthorhombic, Imma
Temperature (K)296
a, b, c (Å)10.2373 (10), 13.8981 (15), 6.6230 (6)
V3)942.31 (16)
Radiation typeMo Kα
µ (mm1)10.14
Crystal size (mm)0.28 × 0.15 × 0.12
Data collection
DiffractometerBruker APEXII
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.164, 0.376
No. of measured, independent and
observed [I > 2σ(I)] reflections
4726, 991, 877
(sin θ/λ)max1)0.773
R[F2 > 2σ(F2)], wR(F2), S 0.025, 0.066, 1.04
No. of reflections991
No. of parameters53
Δρmax, Δρmin (e Å3)0.83, 0.92

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).


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