inorganic compounds
Ni2Sr(PO4)2·2H2O
aLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V-Agdal, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: mohamedsaadi82@gmail.com
The title compound, dinickel(II) strontium bis[orthophosphate(V)] dihydrate, was obtained under hydrothermal conditions. The ∞1[NiO2/2(OH2)2/2O2/1] of edge-sharing NiO6 octahedra ( symmetry) running parallel to [010]. Adjacent chains are linked to each other through PO4 tetrahedra (m symmetry) and arranged in such a way to build layers parallel to (001). The three-dimensional framework is accomplished by stacking of adjacent layers that are held together by SrO8 polyhedra (2/m symmetry). Two types of O—H⋯O hydrogen bonds involving the water molecule are present, viz. one very strong hydrogen bond perpendicular to the layers and weak trifurcated hydrogen bonds parallel to the layers.
consists of linear chainsRelated literature
For catalytic properties of phosphates, see: Cheetham et al. (1999); Clearfield (1988). The of anhydrous Ni2Sr(PO4)2 has been reported by El Bali et al. (1993). For crystal structures of some hydrous orthophosphates of divalent cations, see: Assani et al. (2010); Effenberger (1999); Lee et al. (2008); Britvin et al. (2002); Stock (2002); Yakubovich et al. (2001). 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: WinGX (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536810045113/wm2418sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810045113/wm2418Isup2.hkl
A typical hydrothermal synthesis has allowed to isolate the title compound from the reaction mixture of strontium carbonate (SrCO3; 0.0738 g), metallic nickel (Ni; 0.0881 g) and 85 wt% phosphoric acid (H3PO4; 0,10 ml) and water (H2O; 10 ml). The hydrothermal reaction was performed in a 23 ml Teflon-lined autoclave under autogeneous pressure at 468 K for two days. The product was filtered off, washed with deionized water and air dried. The resulting product consists of parallelepipedic turquoise crystals besides some gray powder.
All O-bound H atoms were initially located in a difference map and refined with O—H (0.85) distance restraints and a common Uiso for both H atoms for the water molecule.
Metal based phosphates continue to be interesting materials due to their remarkable variety of structures, associated with outstanding properties in widespread applications such as catalysis and ion-exchangers (Cheetham et al., 1999; Clearfield, 1988).
Our focus of investigation is associated with mixed divalent orthophosphates with general formula (M,M')3(PO4)2.nH2O (Assani et al., 2010). This family of phosphates goes along with a diversity of structures, depending on the size difference of the (various) divalent cations (Effenberger, 1999) and on the degree of hydratation (Yakubovich et al., 2001; Lee et al., 2008), ranging from 0.5 H2O in the manganese phosphate Mn3(PO4)2.0.5H2O (Stock, 2002) to 22 H2O in the case of Mg3(PO4)2.22H2O (Britvin et al., 2002). A topological comparison with their corresponding anhydrous phosphates clearly reveals substantial differences in their structural set-up.
By means of the hydrothermal method, we have synthesized a the hydrous strontium nickel phosphate, Ni2Sr(PO4)2. 2H2O, representing a novel structure type. A partial three-dimensional plot of the 1 symmetry) and PO4 tetrahedra (m symmetry). Edge-sharing NiO6 octahedra form an infinite chain ∞1[NiO2/2(OH2)2/2O2/1] running parallel to [010], as shown in Fig. 2. Adjacent chains are connected by PO4 tetrahedra and weak trifurcated hydrogen bonds (O4–H1···(O4,O1)) to build up layers parallel to (001). These layers are in turn linked by sheets of Sr2+ cations and by very strong hydrogen bond (O4–H2···O2) as shown in Fig. 2 and Table 2.
of the title compound is represented in Fig. 1, illustrating the connection of the metal-oxygen polyhedra. The network is built up from three different types of polyhedra more or less distorted, viz. SrO8 polyhedra (2/m symmetry) with distances ranging from 2.636 (2) Å to 2.797 (3) Å, NiO6 octahedra (Bond valence sum calculations (Brown & Altermatt, 1985) for Ni2+, Sr2+ and P5+ ions are as expected, viz. 2.03, 1.83 and 4.93 valence units, respectively. The values of the bond valence sums calculated for all oxygen atoms are: 1.83, 1.56 and 1.93 for O1, O2 and O3, respectively. The low bond valence sum of O2 indicates that it is considerably undersaturated and thus acts as an acceptor with a very short H-bond (Table 2).
It is particularly interesting to compare the crystal structures of this compound with that of its corresponding anhydrous phosphate (El Bali et al., 1993). Indeed, both structures can be described by the stacking of two-dimensional layers connected to each other by Sr2+ ions. However, we can note the following important differences: The presence of NiO5 polyhedra in the anhydrous phase and a different 1) and lattice parameters. Moreover, due to the lower symmetry, the polyhedra are more distorted in the anhydrous phase.
(PFor catalytic properties of phosphates, see: Cheetham et al. (1999); Clearfield (1988). The
of anhydrous Ni2Sr(PO4)2 has been reported by El Bali et al. (1993). For crystal structures of some hydrous orthophosphates of divalent cations, see: Assani et al. (2010); Effenberger (1999); Lee et al. (2008); Britvin et al. (2002); Stock (2002); Yakubovich et al. (2001). 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: WinGX (Farrugia, 1999).Fig. 1. Partial plot of Ni2Sr(PO4)2,2H2O crystal structure. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) x - 1/2, -y + 3/2, z; (ii) -x + 3/2, y - 1/2, -z; (iii) -x + 3/2, -y + 3/2, -z; (iv) x - 1/2, y - 1/2, z; (v) -x + 1, -y + 1, -z; (vi) x - 1/2, y + 1/2, z; (vii) -x + 3/2, -y + 1/2, -z; (viii) -x + 3/2, -y + 3/2, -z + 1; (ix) -x + 2, y, -z + 1; (x) x + 1/2, y + 1/2, z + 1; (xi) x, -y + 1, z; (xii) x + 1/2, y - 1/2, z; (xiii) x + 1/2, y + 1/2, z; (xiv) -x + 3/2, y - 1/2, -z + 1; (xv) -x + 2, -y + 1, -z + 1. | |
Fig. 2. A three-dimensional polyhedral view of the crystal structure of the Ni2Sr(PO4)2.2H2O, showing the stacking of layers along the c axis and the hydrogen bonding scheme (dashed lines). |
Ni2Sr(PO4)2·2H2O | F(000) = 416 |
Mr = 431.01 | Dx = 3.958 Mg m−3 |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2y | Cell parameters from 454 reflections |
a = 8.8877 (3) Å | θ = 3.0–27.4° |
b = 6.0457 (3) Å | µ = 12.99 mm−1 |
c = 7.3776 (3) Å | T = 296 K |
β = 114.173 (2)° | Parallelepiped, pale green |
V = 361.66 (3) Å3 | 0.20 × 0.10 × 0.07 mm |
Z = 2 |
Bruker APEXII diffractometer | 454 independent reflections |
Radiation source: fine-focus sealed tube | 439 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.028 |
φ and ω scans | θmax = 27.4°, θmin = 3.0° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −11→11 |
Tmin = 0.229, Tmax = 0.403 | k = −7→7 |
2376 measured reflections | l = −9→9 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.019 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.052 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | w = 1/[σ2(Fo2) + (0.0243P)2 + 1.4658P] where P = (Fo2 + 2Fc2)/3 |
454 reflections | (Δ/σ)max < 0.001 |
49 parameters | Δρmax = 0.41 e Å−3 |
3 restraints | Δρmin = −0.69 e Å−3 |
Ni2Sr(PO4)2·2H2O | V = 361.66 (3) Å3 |
Mr = 431.01 | Z = 2 |
Monoclinic, C2/m | Mo Kα radiation |
a = 8.8877 (3) Å | µ = 12.99 mm−1 |
b = 6.0457 (3) Å | T = 296 K |
c = 7.3776 (3) Å | 0.20 × 0.10 × 0.07 mm |
β = 114.173 (2)° |
Bruker APEXII diffractometer | 454 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 439 reflections with I > 2σ(I) |
Tmin = 0.229, Tmax = 0.403 | Rint = 0.028 |
2376 measured reflections |
R[F2 > 2σ(F2)] = 0.019 | 3 restraints |
wR(F2) = 0.052 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | Δρmax = 0.41 e Å−3 |
454 reflections | Δρmin = −0.69 e Å−3 |
49 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Sr1 | 0.5000 | 0.5000 | 0.0000 | 0.01385 (17) | |
Ni1 | 0.7500 | 0.7500 | 0.5000 | 0.00948 (17) | |
P1 | 0.91308 (11) | 0.5000 | 0.22145 (14) | 0.0053 (2) | |
O1 | 1.0211 (2) | 0.7094 (3) | 0.2739 (3) | 0.0110 (4) | |
O2 | 0.7975 (3) | 0.5000 | 0.0027 (4) | 0.0143 (6) | |
O3 | 0.7992 (3) | 0.5000 | 0.3363 (4) | 0.0084 (5) | |
O4 | 0.6779 (3) | 0.5000 | 0.6298 (4) | 0.0128 (6) | |
H1 | 0.577 (4) | 0.5000 | 0.610 (13) | 0.15 (4)* | |
H2 | 0.730 (10) | 0.5000 | 0.755 (4) | 0.15 (4)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sr1 | 0.0089 (3) | 0.0253 (3) | 0.0071 (3) | 0.000 | 0.00297 (19) | 0.000 |
Ni1 | 0.0100 (3) | 0.0095 (3) | 0.0083 (3) | 0.00375 (18) | 0.00307 (19) | 0.00014 (19) |
P1 | 0.0045 (4) | 0.0055 (5) | 0.0059 (5) | 0.000 | 0.0020 (3) | 0.000 |
O1 | 0.0090 (9) | 0.0104 (10) | 0.0116 (10) | −0.0040 (8) | 0.0021 (7) | 0.0013 (8) |
O2 | 0.0100 (13) | 0.0226 (17) | 0.0080 (15) | 0.000 | 0.0014 (11) | 0.000 |
O3 | 0.0084 (12) | 0.0086 (14) | 0.0107 (13) | 0.000 | 0.0066 (10) | 0.000 |
O4 | 0.0076 (13) | 0.0211 (17) | 0.0107 (14) | 0.000 | 0.0047 (11) | 0.000 |
Sr1—O1i | 2.626 (2) | Ni1—O1i | 2.0499 (19) |
Sr1—O1ii | 2.626 (2) | Ni1—O1vii | 2.0499 (19) |
Sr1—O1iii | 2.626 (2) | Ni1—O3vi | 2.0895 (18) |
Sr1—O1iv | 2.626 (2) | Ni1—O3 | 2.0895 (18) |
Sr1—O2v | 2.636 (3) | P1—O2 | 1.517 (3) |
Sr1—O2 | 2.636 (3) | P1—O1viii | 1.539 (2) |
Sr1—O3 | 2.797 (3) | P1—O1 | 1.539 (2) |
Sr1—O3v | 2.797 (3) | P1—O3 | 1.564 (3) |
Ni1—O4vi | 2.0285 (19) | O4—H1 | 0.85 (5) |
Ni1—O4 | 2.0285 (19) | O4—H2 | 0.85 (5) |
O1i—Sr1—O1ii | 180.0 | O1i—Ni1—O1vii | 180.0 |
O1i—Sr1—O1iii | 96.00 (9) | O4vi—Ni1—O3vi | 85.13 (8) |
O1ii—Sr1—O1iii | 84.00 (9) | O4—Ni1—O3vi | 94.87 (8) |
O1i—Sr1—O1iv | 84.00 (9) | O1i—Ni1—O3vi | 90.62 (9) |
O1ii—Sr1—O1iv | 96.00 (9) | O1vii—Ni1—O3vi | 89.38 (9) |
O1iii—Sr1—O1iv | 180.00 (7) | O4vi—Ni1—O3 | 94.87 (8) |
O1i—Sr1—O2v | 76.18 (6) | O4—Ni1—O3 | 85.13 (8) |
O1ii—Sr1—O2v | 103.82 (6) | O1i—Ni1—O3 | 89.38 (10) |
O1iii—Sr1—O2v | 103.82 (6) | O1vii—Ni1—O3 | 90.62 (9) |
O1iv—Sr1—O2v | 76.18 (6) | O3vi—Ni1—O3 | 180.0 |
O1i—Sr1—O2 | 103.82 (6) | O2—P1—O1viii | 110.38 (10) |
O1ii—Sr1—O2 | 76.18 (6) | O2—P1—O1 | 110.38 (10) |
O1iii—Sr1—O2 | 76.18 (6) | O1viii—P1—O1 | 110.64 (16) |
O1iv—Sr1—O2 | 103.82 (6) | O2—P1—O3 | 105.67 (16) |
O2v—Sr1—O2 | 180.0 | O1viii—P1—O3 | 109.83 (10) |
O1i—Sr1—O3 | 64.85 (6) | O1—P1—O3 | 109.83 (10) |
O1ii—Sr1—O3 | 115.15 (6) | P1—O1—Ni1vii | 127.73 (12) |
O1iii—Sr1—O3 | 115.15 (6) | P1—O1—Sr1ix | 121.08 (11) |
O1iv—Sr1—O3 | 64.85 (6) | Ni1vii—O1—Sr1ix | 106.29 (8) |
O2v—Sr1—O3 | 126.37 (8) | P1—O2—Sr1 | 104.37 (14) |
O2—Sr1—O3 | 53.63 (8) | P1—O3—Ni1 | 130.42 (7) |
O1i—Sr1—O3v | 115.15 (6) | P1—O3—Ni1x | 130.42 (7) |
O1ii—Sr1—O3v | 64.85 (6) | Ni1—O3—Ni1x | 92.66 (11) |
O1iii—Sr1—O3v | 64.85 (6) | P1—O3—Sr1 | 96.33 (13) |
O1iv—Sr1—O3v | 115.15 (6) | Ni1—O3—Sr1 | 99.48 (8) |
O2v—Sr1—O3v | 53.63 (8) | Ni1x—O3—Sr1 | 99.48 (8) |
O2—Sr1—O3v | 126.37 (8) | Ni1x—O4—Ni1 | 96.34 (12) |
O3—Sr1—O3v | 180.00 (9) | Ni1x—O4—H1 | 116 (3) |
O4vi—Ni1—O4 | 180.0 | Ni1—O4—H1 | 116 (3) |
O4vi—Ni1—O1i | 85.80 (10) | Ni1x—O4—H2 | 112 (4) |
O4—Ni1—O1i | 94.20 (10) | Ni1—O4—H2 | 112 (4) |
O4vi—Ni1—O1vii | 94.20 (10) | H1—O4—H2 | 105 (8) |
O4—Ni1—O1vii | 85.80 (10) |
Symmetry codes: (i) x−1/2, −y+3/2, z; (ii) −x+3/2, y−1/2, −z; (iii) −x+3/2, −y+3/2, −z; (iv) x−1/2, y−1/2, z; (v) −x+1, −y+1, −z; (vi) −x+3/2, −y+3/2, −z+1; (vii) −x+2, y, −z+1; (viii) x, −y+1, z; (ix) x+1/2, y+1/2, z; (x) −x+3/2, y−1/2, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H1···O4xi | 0.85 (6) | 2.23 (7) | 2.951 (4) | 143 (7) |
O4—H1···O1vi | 0.85 (6) | 2.28 (4) | 2.784 (3) | 118 (4) |
O4—H1···O1x | 0.85 (6) | 2.28 (4) | 2.784 (3) | 118 (4) |
O4—H2···O2xii | 0.85 (3) | 1.67 (3) | 2.511 (4) | 169 (9) |
Symmetry codes: (vi) −x+3/2, −y+3/2, −z+1; (x) −x+3/2, y−1/2, −z+1; (xi) −x+1, −y+1, −z+1; (xii) x, y, z+1. |
Experimental details
Crystal data | |
Chemical formula | Ni2Sr(PO4)2·2H2O |
Mr | 431.01 |
Crystal system, space group | Monoclinic, C2/m |
Temperature (K) | 296 |
a, b, c (Å) | 8.8877 (3), 6.0457 (3), 7.3776 (3) |
β (°) | 114.173 (2) |
V (Å3) | 361.66 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 12.99 |
Crystal size (mm) | 0.20 × 0.10 × 0.07 |
Data collection | |
Diffractometer | Bruker APEXII |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.229, 0.403 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2376, 454, 439 |
Rint | 0.028 |
(sin θ/λ)max (Å−1) | 0.648 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.019, 0.052, 1.12 |
No. of reflections | 454 |
No. of parameters | 49 |
No. of restraints | 3 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.41, −0.69 |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia,1997) and DIAMOND (Brandenburg, 2006), WinGX (Farrugia, 1999).
Sr1—O1i | 2.626 (2) | Ni1—O3 | 2.0895 (18) |
Sr1—O2 | 2.636 (3) | P1—O2 | 1.517 (3) |
Sr1—O3 | 2.797 (3) | P1—O1 | 1.539 (2) |
Ni1—O4 | 2.0285 (19) | P1—O3 | 1.564 (3) |
Ni1—O1ii | 2.0499 (19) |
Symmetry codes: (i) x−1/2, −y+3/2, z; (ii) −x+2, y, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H1···O4iii | 0.85 (6) | 2.23 (7) | 2.951 (4) | 143 (7) |
O4—H1···O1iv | 0.85 (6) | 2.28 (4) | 2.784 (3) | 118 (4) |
O4—H1···O1v | 0.85 (6) | 2.28 (4) | 2.784 (3) | 118 (4) |
O4—H2···O2vi | 0.85 (3) | 1.67 (3) | 2.511 (4) | 169 (9) |
Symmetry codes: (iii) −x+1, −y+1, −z+1; (iv) −x+3/2, −y+3/2, −z+1; (v) −x+3/2, y−1/2, −z+1; (vi) x, y, z+1. |
Acknowledgements
The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray data collection.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Metal based phosphates continue to be interesting materials due to their remarkable variety of structures, associated with outstanding properties in widespread applications such as catalysis and ion-exchangers (Cheetham et al., 1999; Clearfield, 1988).
Our focus of investigation is associated with mixed divalent orthophosphates with general formula (M,M')3(PO4)2.nH2O (Assani et al., 2010). This family of phosphates goes along with a diversity of structures, depending on the size difference of the (various) divalent cations (Effenberger, 1999) and on the degree of hydratation (Yakubovich et al., 2001; Lee et al., 2008), ranging from 0.5 H2O in the manganese phosphate Mn3(PO4)2.0.5H2O (Stock, 2002) to 22 H2O in the case of Mg3(PO4)2.22H2O (Britvin et al., 2002). A topological comparison with their corresponding anhydrous phosphates clearly reveals substantial differences in their structural set-up.
By means of the hydrothermal method, we have synthesized a the hydrous strontium nickel phosphate, Ni2Sr(PO4)2. 2H2O, representing a novel structure type. 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. The network is built up from three different types of polyhedra more or less distorted, viz. SrO8 polyhedra (2/m symmetry) with distances ranging from 2.636 (2) Å to 2.797 (3) Å, NiO6 octahedra (1 symmetry) and PO4 tetrahedra (m symmetry). Edge-sharing NiO6 octahedra form an infinite chain ∞1[NiO2/2(OH2)2/2O2/1] running parallel to [010], as shown in Fig. 2. Adjacent chains are connected by PO4 tetrahedra and weak trifurcated hydrogen bonds (O4–H1···(O4,O1)) to build up layers parallel to (001). These layers are in turn linked by sheets of Sr2+ cations and by very strong hydrogen bond (O4–H2···O2) as shown in Fig. 2 and Table 2.
Bond valence sum calculations (Brown & Altermatt, 1985) for Ni2+, Sr2+ and P5+ ions are as expected, viz. 2.03, 1.83 and 4.93 valence units, respectively. The values of the bond valence sums calculated for all oxygen atoms are: 1.83, 1.56 and 1.93 for O1, O2 and O3, respectively. The low bond valence sum of O2 indicates that it is considerably undersaturated and thus acts as an acceptor with a very short H-bond (Table 2).
It is particularly interesting to compare the crystal structures of this compound with that of its corresponding anhydrous phosphate (El Bali et al., 1993). Indeed, both structures can be described by the stacking of two-dimensional layers connected to each other by Sr2+ ions. However, we can note the following important differences: The presence of NiO5 polyhedra in the anhydrous phase and a different space group (P1) and lattice parameters. Moreover, due to the lower symmetry, the polyhedra are more distorted in the anhydrous phase.