inorganic compounds
Dilead(II) trimanganese(II) bis(hydrogenphosphate) bis(phosphate)
aLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V-Agdal, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: m_zriouil@yahoo.fr
The title compound, Pb2Mn3(HPO4)2(PO4)2, was synthesized by a hydrothermal method. All atoms are in general positions except for one Mn atom which is located on an inversion center. The framework of the structure is built up from PO4 tetrahedra and two types of MnO6 octahedra, one almost ideal and the other very distorted with one very long Mn—O bond [2.610 (4) Å compared an average of 2.161 Å for the other bonds]. The centrosymetric octahedron is linked to two distorted MnO6 octahedra by an edge common, forming infinite zigzag Mn3O14 chains running along the b axis. Adjacent chains are linked by PO4 and PO3(OH) tetrahedra through vertices or by edge sharing, forming sheets perpendicular to [100]. The Pb2+ cations are sandwiched between the layers and ensure the cohesion of the O—H⋯O hydrogen bonding between the layers is also observed.
Related literature
For properties of phosphates and their potential applications, see: Gao & Gao (2005); Viter & Nagornyi (2009); Clearfield (1988); Trad et al. (2010). For compounds with related structures, see: Assani et al. (2010, 2011a,b,c, 2012); Effenberger (1999). For bond-valence analysis, see: Brown & Altermatt (1985).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2005); cell SAINT (Bruker, 2005); data reduction: SAINT; 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, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).
Supporting information
https://doi.org/10.1107/S1600536812033259/hp2043sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812033259/hp2043Isup2.hkl
The crystals of the title compound is isolated from the hydrothermal treatment of the reaction mixture of lead oxide, metallic manganese and 85wt% phosphoric acid in a proportion corresponding to the molar ratio Pb:Mn:P = 1,5: 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 twenty hours. After being filtered off, washed with deionized water and air dried, the reaction product consists of a light brown solid and colorless sheet shaped crystals corresponding to the title compound.
The O-bound H atoms were initially located in a difference map and refined with O—H distance restraints of 0.86 (1). In the last cycle they were refined in the riding model approximation with Uiso(H) set to 1.2Ueq(O). The highest peak and the deepest hole in the final Fourier map are at 0.62 Å and 0.67 Å, respectively, from Pb1. The not significants bonds and angles were removed from the
file.Owing to their remarkable variety of structures and to their outstanding potentialities in widespread applications such as catalysis (Viter & Nagornyi, 2009; Gao & Gao, 2005) and ion-exchangers (Clearfield, 1988) and in batteries performance (Trad et al., (2010)), transition metal based phosphates have received great attention and still remains in the forefront of the developed scientific axes in our laboratory. Within this family of compounds, the resulting anionic frameworks, generally constructed from the alternation of PO4 tetrahedra connected to metal cations in different coordinate geometry MOn (with n=4, 5 and 6), generate pores and channels offering suitable environment to accommodate different other cations. Accordingly, we have succeeded to isolate new silver metal based orthophosphates for instance, AgMg3(PO4)(HPO4)2 wich represent a new member of the well known alluaudite-like structure family (Assani et al. 2011a); silver (nickel or cobalt) phosphate, namely, Ag2M3(HPO4)(PO4)2 with M=Ni, Co (Assani et al. 2011b; Assani et al. 2011c). Furthermore, a special attention have been paid to the ternary system MO—M'O—P2O5 with M=Ba, Ca, Cd, Pb and Sr and M'= transition metals, Mg and Zn. Our recent investigation has allowed to the isolate the compounds Ni2Sr(PO4)2.2H2O (Assani et al. 2010) and Co2Pb(HPO4)(PO4)OH H2O (Assani et al. 2012).
Inline with the focus of our research, the present paper aims to develop the hydrothermal synthesis and the structural characterization of a new layered lead manganese orthophosphate, namely, PbMn1.5(PO4)(HPO4), which is characterized by Mn/P ratio =3/4, rarely encountered in the literature with the exception of some copper based orthophosphates, Pb3Cu3(PO4)4 and Sr3Cu3(PO4)4 (Effenberger 1999).
A partial three-dimensional plot of the 1) 2a (0 0 0; 0 1/2 1/2) of P21/c The network is built up from two different types of polyhedra more or less distorted, viz. PO4, HPO4 tetrahedra and Mn1O6 (1 symmetry), Mn2O6 octahedra. Moreover, the edge-sharing Mn1O6 and Mn2O5(OH) octahedra form an infinite zigzag chains 1∞ [Mn3O14] running parallel to [010], as shown in Fig. 2. Adjacent chains are connected by PO4 and HPO4 tetrahedra via vertices in the way to build layers parallel to (100). These layers are in turn linked by Pb2+ cations as shown in Fig.2. The strong hydrogen bonding between the layers is also involved in the stability of this structure (Fig. 2 and Table 2).
of PbMn1.5(PO4)(HPO4) is represented in Fig. 1. A l l atoms of this structure are in general positions, except one manganese Mn1 located in symmetry center (Bond valence sum calculations (Brown & Altermatt, 1985) for Pb12+, Mn12+, Mb22+, P15+ and P25+ ions are as expected, viz. 1.82, 2.13, 1.97, 4.95 and 5.01 valence units, respectively. The values of the bond valence sums calculated for all oxygen atoms are between 1.93 and 2.05 except O4 and O8 which shown low values: 1.62 and 1.50 respectively. These atoms are considerably undersaturated and thus act as an acceptor with a very short H-bond (Table 2, Fig.1).
For properties of phosphates and their potential applications, see: Gao & Gao (2005); Viter & Nagornyi (2009); Clearfield (1988); Trad et al., (2010). For compounds with related structures, see: Assani et al. (2010, 2011a,b,c, 2012); Effenberger (1999). For bond-valence analysis, see: Brown & Altermatt (1985).
Data collection: APEX2 (Bruker, 2005); cell
SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); 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, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).Pb2Mn3(HPO4)2(PO4)2 | F(000) = 858 |
Mr = 961.10 | Dx = 4.808 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 1225 reflections |
a = 7.9449 (2) Å | θ = 2.6–25.4° |
b = 8.8911 (2) Å | µ = 28.63 mm−1 |
c = 9.5718 (3) Å | T = 296 K |
β = 100.917 (2)° | Prism, pink |
V = 663.90 (3) Å3 | 0.18 × 0.12 × 0.08 mm |
Z = 2 |
Bruker X8 APEXII diffractometer | 1225 independent reflections |
Radiation source: fine-focus sealed tube | 1202 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.044 |
φ and ω scans | θmax = 25.4°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −9→9 |
Tmin = 0.029, Tmax = 0.117 | k = −10→10 |
8738 measured reflections | l = −11→11 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.020 | H-atom parameters constrained |
wR(F2) = 0.051 | w = 1/[σ2(Fo2) + (0.0232P)2 + 2.912P] where P = (Fo2 + 2Fc2)/3 |
S = 1.10 | (Δ/σ)max = 0.001 |
1225 reflections | Δρmax = 1.37 e Å−3 |
116 parameters | Δρmin = −2.03 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0091 (4) |
Pb2Mn3(HPO4)2(PO4)2 | V = 663.90 (3) Å3 |
Mr = 961.10 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.9449 (2) Å | µ = 28.63 mm−1 |
b = 8.8911 (2) Å | T = 296 K |
c = 9.5718 (3) Å | 0.18 × 0.12 × 0.08 mm |
β = 100.917 (2)° |
Bruker X8 APEXII diffractometer | 1225 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 1202 reflections with I > 2σ(I) |
Tmin = 0.029, Tmax = 0.117 | Rint = 0.044 |
8738 measured reflections |
R[F2 > 2σ(F2)] = 0.020 | 0 restraints |
wR(F2) = 0.051 | H-atom parameters constrained |
S = 1.10 | Δρmax = 1.37 e Å−3 |
1225 reflections | Δρmin = −2.03 e Å−3 |
116 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Pb1 | 0.41097 (3) | 0.52400 (2) | 0.75343 (2) | 0.01734 (13) | |
Mn1 | 0.0000 | 0.5000 | 0.5000 | 0.0091 (2) | |
Mn2 | 0.10770 (9) | 0.13892 (8) | 0.59303 (7) | 0.00981 (19) | |
P1 | 0.14019 (16) | 0.70441 (14) | 0.23105 (12) | 0.0076 (3) | |
P2 | 0.65619 (16) | 0.70724 (14) | 0.56583 (12) | 0.0087 (3) | |
O1 | 0.0496 (5) | 0.6808 (4) | 0.3570 (4) | 0.0123 (7) | |
O2 | 0.0740 (5) | 0.5969 (4) | 0.1080 (3) | 0.0122 (7) | |
O3 | 0.1156 (5) | 0.8690 (4) | 0.1828 (4) | 0.0127 (7) | |
O4 | 0.3370 (5) | 0.6828 (4) | 0.2816 (4) | 0.0133 (7) | |
O5 | 0.7064 (5) | 0.6754 (5) | 0.7236 (4) | 0.0208 (9) | |
O6 | 0.7536 (5) | 0.6118 (4) | 0.4742 (4) | 0.0152 (8) | |
O7 | 0.6777 (5) | 0.8718 (4) | 0.5276 (4) | 0.0212 (9) | |
O8 | 0.4617 (5) | 0.6642 (4) | 0.5341 (4) | 0.0146 (7) | |
H8 | 0.4002 | 0.6667 | 0.4499 | 0.022* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pb1 | 0.01783 (17) | 0.01676 (17) | 0.01923 (17) | 0.00271 (7) | 0.00812 (10) | 0.00201 (7) |
Mn1 | 0.0108 (6) | 0.0084 (5) | 0.0080 (5) | 0.0006 (4) | 0.0018 (4) | 0.0002 (4) |
Mn2 | 0.0096 (4) | 0.0107 (4) | 0.0082 (4) | 0.0003 (3) | −0.0008 (3) | −0.0006 (3) |
P1 | 0.0080 (6) | 0.0090 (6) | 0.0055 (6) | −0.0004 (5) | 0.0003 (5) | 0.0003 (4) |
P2 | 0.0080 (6) | 0.0111 (6) | 0.0067 (6) | −0.0007 (5) | 0.0009 (5) | −0.0005 (4) |
O1 | 0.0154 (19) | 0.0110 (17) | 0.0120 (17) | −0.0005 (14) | 0.0068 (14) | 0.0016 (13) |
O2 | 0.0154 (19) | 0.0111 (17) | 0.0076 (16) | 0.0002 (14) | −0.0045 (14) | −0.0020 (13) |
O3 | 0.0154 (19) | 0.0099 (17) | 0.0120 (17) | 0.0005 (14) | 0.0008 (14) | 0.0026 (14) |
O4 | 0.0083 (18) | 0.0234 (19) | 0.0078 (16) | 0.0002 (14) | 0.0004 (13) | −0.0002 (14) |
O5 | 0.015 (2) | 0.038 (2) | 0.0076 (18) | 0.0013 (17) | −0.0021 (14) | 0.0035 (16) |
O6 | 0.0113 (18) | 0.0200 (19) | 0.0153 (17) | 0.0061 (15) | 0.0048 (14) | 0.0015 (15) |
O7 | 0.030 (2) | 0.0118 (18) | 0.026 (2) | −0.0036 (16) | 0.0151 (18) | −0.0013 (16) |
O8 | 0.0087 (17) | 0.0261 (19) | 0.0079 (16) | −0.0034 (15) | −0.0012 (14) | 0.0016 (15) |
Pb1—O3i | 2.504 (4) | P1—O3 | 1.536 (3) |
Pb1—O8 | 2.539 (4) | P1—O4 | 1.559 (4) |
Pb1—O6ii | 2.614 (4) | P2—O5 | 1.514 (4) |
Pb1—O4i | 2.697 (4) | P2—O7 | 1.526 (4) |
Pb1—O7iii | 2.698 (4) | P2—O6 | 1.532 (4) |
Pb1—O5 | 2.767 (4) | P2—O8 | 1.565 (4) |
Pb1—O4ii | 2.785 (4) | O1—Mn2vi | 2.141 (4) |
Mn1—O3iv | 2.157 (3) | O2—Mn2viii | 2.122 (4) |
Mn1—O3i | 2.157 (3) | O2—Mn2ix | 2.208 (3) |
Mn1—O6ii | 2.168 (3) | O3—Mn1ix | 2.157 (3) |
Mn1—O6v | 2.168 (3) | O3—Pb1x | 2.504 (4) |
Mn1—O1 | 2.195 (3) | O4—Pb1x | 2.697 (4) |
Mn1—O1vi | 2.195 (3) | O4—Pb1ii | 2.785 (4) |
Mn2—O5iii | 2.094 (4) | O5—Mn2xi | 2.094 (4) |
Mn2—O2vii | 2.122 (4) | O6—Mn1xii | 2.168 (3) |
Mn2—O1vi | 2.141 (4) | O6—Mn2ii | 2.610 (4) |
Mn2—O2iv | 2.208 (3) | O6—Pb1ii | 2.614 (4) |
Mn2—O7ii | 2.235 (4) | O7—Mn2ii | 2.235 (4) |
Mn2—O6ii | 2.610 (4) | O7—Pb1xi | 2.698 (4) |
P1—O2 | 1.530 (3) | O8—H8 | 0.8600 |
P1—O1 | 1.531 (3) | ||
O3i—Pb1—O8 | 82.97 (11) | O3i—Mn1—O1vi | 89.35 (13) |
O3i—Pb1—O6ii | 69.84 (11) | O6ii—Mn1—O1vi | 81.84 (13) |
O8—Pb1—O6ii | 70.75 (11) | O6v—Mn1—O1vi | 98.16 (13) |
O3i—Pb1—O4i | 56.56 (11) | O1—Mn1—O1vi | 180.000 (1) |
O8—Pb1—O4i | 71.32 (11) | O5iii—Mn2—O2vii | 100.04 (15) |
O6ii—Pb1—O4i | 116.47 (11) | O5iii—Mn2—O1vi | 92.62 (15) |
O3i—Pb1—O7iii | 91.78 (12) | O2vii—Mn2—O1vi | 129.62 (14) |
O8—Pb1—O7iii | 173.95 (12) | O5iii—Mn2—O2iv | 176.09 (15) |
O6ii—Pb1—O7iii | 104.65 (12) | O2vii—Mn2—O2iv | 79.73 (13) |
O4i—Pb1—O7iii | 108.25 (11) | O1vi—Mn2—O2iv | 90.49 (14) |
O3i—Pb1—O5 | 123.87 (12) | O5iii—Mn2—O7ii | 87.34 (15) |
O8—Pb1—O5 | 53.50 (11) | O2vii—Mn2—O7ii | 96.38 (14) |
O6ii—Pb1—O5 | 116.03 (11) | O1vi—Mn2—O7ii | 133.01 (14) |
O4i—Pb1—O5 | 75.23 (12) | O2iv—Mn2—O7ii | 88.81 (14) |
O7iii—Pb1—O5 | 132.49 (12) | O5iii—Mn2—O6ii | 79.12 (14) |
O3i—Pb1—O4ii | 151.26 (10) | O2vii—Mn2—O6ii | 157.01 (13) |
O8—Pb1—O4ii | 89.67 (11) | O1vi—Mn2—O6ii | 73.21 (12) |
O6ii—Pb1—O4ii | 81.50 (10) | O2iv—Mn2—O6ii | 99.54 (12) |
O4i—Pb1—O4ii | 145.63 (8) | O7ii—Mn2—O6ii | 60.65 (12) |
O7iii—Pb1—O4ii | 93.55 (11) | O2—P1—O1 | 112.1 (2) |
O5—Pb1—O4ii | 70.46 (12) | O2—P1—O3 | 111.0 (2) |
O3iv—Mn1—O3i | 180.000 (1) | O1—P1—O3 | 108.4 (2) |
O3iv—Mn1—O6ii | 94.68 (14) | O2—P1—O4 | 109.9 (2) |
O3i—Mn1—O6ii | 85.32 (14) | O1—P1—O4 | 109.4 (2) |
O3iv—Mn1—O6v | 85.32 (14) | O3—P1—O4 | 105.9 (2) |
O3i—Mn1—O6v | 94.68 (14) | O5—P2—O7 | 113.5 (2) |
O6ii—Mn1—O6v | 180.00 (19) | O5—P2—O6 | 113.7 (2) |
O3iv—Mn1—O1 | 89.35 (13) | O7—P2—O6 | 107.6 (2) |
O3i—Mn1—O1 | 90.65 (13) | O5—P2—O8 | 102.2 (2) |
O6ii—Mn1—O1 | 98.16 (13) | O7—P2—O8 | 109.8 (2) |
O6v—Mn1—O1 | 81.84 (13) | O6—P2—O8 | 109.9 (2) |
O3iv—Mn1—O1vi | 90.65 (13) |
Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, −y+1, −z+1; (iii) −x+1, y−1/2, −z+3/2; (iv) −x, y−1/2, −z+1/2; (v) x−1, y, z; (vi) −x, −y+1, −z+1; (vii) x, −y+1/2, z+1/2; (viii) x, −y+1/2, z−1/2; (ix) −x, y+1/2, −z+1/2; (x) x, −y+3/2, z−1/2; (xi) −x+1, y+1/2, −z+3/2; (xii) x+1, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O8—H8···O4 | 0.86 | 1.60 | 2.437 (5) | 164 |
O8—H8···O1 | 0.86 | 2.76 | 3.393 (5) | 132 |
Experimental details
Crystal data | |
Chemical formula | Pb2Mn3(HPO4)2(PO4)2 |
Mr | 961.10 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 7.9449 (2), 8.8911 (2), 9.5718 (3) |
β (°) | 100.917 (2) |
V (Å3) | 663.90 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 28.63 |
Crystal size (mm) | 0.18 × 0.12 × 0.08 |
Data collection | |
Diffractometer | Bruker X8 APEXII |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.029, 0.117 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8738, 1225, 1202 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.602 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.020, 0.051, 1.10 |
No. of reflections | 1225 |
No. of parameters | 116 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.37, −2.03 |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 2006), PLATON (Spek, 2009) and publCIF (Westrip, 2010).
D—H···A | D—H | H···A | D···A | D—H···A |
O8—H8···O4 | 0.86 | 1.60 | 2.437 (5) | 163.7 |
O8—H8···O1 | 0.86 | 2.76 | 3.393 (5) | 131.5 |
Acknowledgements
The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.
References
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Owing to their remarkable variety of structures and to their outstanding potentialities in widespread applications such as catalysis (Viter & Nagornyi, 2009; Gao & Gao, 2005) and ion-exchangers (Clearfield, 1988) and in batteries performance (Trad et al., (2010)), transition metal based phosphates have received great attention and still remains in the forefront of the developed scientific axes in our laboratory. Within this family of compounds, the resulting anionic frameworks, generally constructed from the alternation of PO4 tetrahedra connected to metal cations in different coordinate geometry MOn (with n=4, 5 and 6), generate pores and channels offering suitable environment to accommodate different other cations. Accordingly, we have succeeded to isolate new silver metal based orthophosphates for instance, AgMg3(PO4)(HPO4)2 wich represent a new member of the well known alluaudite-like structure family (Assani et al. 2011a); silver (nickel or cobalt) phosphate, namely, Ag2M3(HPO4)(PO4)2 with M=Ni, Co (Assani et al. 2011b; Assani et al. 2011c). Furthermore, a special attention have been paid to the ternary system MO—M'O—P2O5 with M=Ba, Ca, Cd, Pb and Sr and M'= transition metals, Mg and Zn. Our recent investigation has allowed to the isolate the compounds Ni2Sr(PO4)2.2H2O (Assani et al. 2010) and Co2Pb(HPO4)(PO4)OH H2O (Assani et al. 2012).
Inline with the focus of our research, the present paper aims to develop the hydrothermal synthesis and the structural characterization of a new layered lead manganese orthophosphate, namely, PbMn1.5(PO4)(HPO4), which is characterized by Mn/P ratio =3/4, rarely encountered in the literature with the exception of some copper based orthophosphates, Pb3Cu3(PO4)4 and Sr3Cu3(PO4)4 (Effenberger 1999).
A partial three-dimensional plot of the crystal structure of PbMn1.5(PO4)(HPO4) is represented in Fig. 1. A l l atoms of this structure are in general positions, except one manganese Mn1 located in symmetry center (1) 2a (0 0 0; 0 1/2 1/2) of P21/c space group. The network is built up from two different types of polyhedra more or less distorted, viz. PO4, HPO4 tetrahedra and Mn1O6 (1 symmetry), Mn2O6 octahedra. Moreover, the edge-sharing Mn1O6 and Mn2O5(OH) octahedra form an infinite zigzag chains 1∞ [Mn3O14] running parallel to [010], as shown in Fig. 2. Adjacent chains are connected by PO4 and HPO4 tetrahedra via vertices in the way to build layers parallel to (100). These layers are in turn linked by Pb2+ cations as shown in Fig.2. The strong hydrogen bonding between the layers is also involved in the stability of this structure (Fig. 2 and Table 2).
Bond valence sum calculations (Brown & Altermatt, 1985) for Pb12+, Mn12+, Mb22+, P15+ and P25+ ions are as expected, viz. 1.82, 2.13, 1.97, 4.95 and 5.01 valence units, respectively. The values of the bond valence sums calculated for all oxygen atoms are between 1.93 and 2.05 except O4 and O8 which shown low values: 1.62 and 1.50 respectively. These atoms are considerably undersaturated and thus act as an acceptor with a very short H-bond (Table 2, Fig.1).