metal-organic compounds
catena-Poly[[[tetraaquamagnesium]-trans-μ-[(piperazine-1,4-diium-1,4-diyl)bis(methylene)]diphosphonato] hemihydrate]
aInstitut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth-Strasse 2, 24118 Kiel, Germany
*Correspondence e-mail: stock@ac.uni-kiel.de
The structure of the title polymer, }[Mg(C6H14N2O6P2)(H2O)4]·0.5H2O}n, is based on centrosymmetric MgO6 octahedra, which are linked by [(piperazine-1,4-diium-1,4-diyl)bis(methylene)]diphosphonate ligands, forming chains parallel to [1-1-1]. These chains are connected via hydrogen bonds primarily formed between the phosphonate groups and water molecules. The latter constitute four of the corners of the MgO6 polyhedra and bind to the O atoms of the phosphonate groups of neighbouring chains. The lattice water molecule is disordered around an inversion centre, exhibiting an occupancy of 0.25.
Related literature
For related magnesium structures, see: Wharmby et al. (2012). For related N,N′-piperaziniumbis(methylenephosphonates), see: Choi et al. (1994); Groves et al. (2005a,b); Groves, Stephens et al. (2006); Groves, Miller et al. (2006); LaDuca et al. (1996); Serre et al. (2006); Soghomonian et al. (1995); Wang et al. (2004); Wharmby et al. (2012). As a result of their flexible coordination behaviour, organic linker molecules containing phosphonate groups allow the synthesis of a multitude of inorganic-organic hybrid materials, see: Gagnon et al. (2012).
Experimental
Crystal data
|
Data collection: X-AREA (Stoe & Cie, 2008); cell X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and DIAMOND Brandenburg (2011); software used to prepare material for publication: XCIF in SHELXTL.
Supporting information
10.1107/S1600536813018722/cq2003sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536813018722/cq2003Isup2.hkl
A reaction mixture of MgCl2 . 6 H2O (13.55 mg, 50 µmol), N,N'-piperazinebis(methylenephosphonic acid) (36.55 mg, 100 nmol), potassium hydroxide (16.83 mg, 300 nmol) and 1.5 ml water was placed in a 2 ml Teflon-lined autoclave. Subsequently the reactor was heated from room temperature to 130 °C (heating rate 1 °C min-1), the temperature was held for 52 h and then slowly lowered to room temperature over a period of 12 h. The resulting colourless crystals were collected by filtration and analysed via single-crystal XRD. Yield: 32%.
All H atoms of C—H groups were located in difference maps but were positioned with idealized geometry and were refined isotropically with Uiso(H) = 1.2 Ueq(C) using a riding model with C—H = 0.97 Å for aliphatic H atoms. The water H atoms were located in difference maps, their bond lengths were set to ideal values of 0.82 Å and they were refined using a riding model with Uiso(H) = 1.5 Ueq(O). The N—H H atom was located in a difference map but was positioned with idealized geometry and was refined isotropic with Uiso(H) = 1.2 Ueq(C) using a riding model with N—H = 0.86 Å.
Data collection: X-AREA (Stoe & Cie, 2008); cell
X-AREA (Stoe & Cie, 2008); data reduction: X-AREA (Stoe & Cie, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and DIAMOND Brandenburg (2011);; software used to prepare material for publication: XCIF in SHELXTL (Sheldrick, 2008).Fig. 1. : Asymmetric unit of the title compound with labeling and displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. : Chain-formed building unit of [Mg(H2O)4(H2L)] . 0.5 H2O. |
[Mg(C6H14N2O6P2)(H2O)4]·0.5H2O | Z = 1 |
Mr = 377.51 | F(000) = 199 |
Triclinic, P1 | Dx = 1.714 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.6296 (5) Å | Cell parameters from 1270 reflections |
b = 6.8074 (6) Å | θ = 1.2–29.8° |
c = 8.7962 (7) Å | µ = 0.40 mm−1 |
α = 94.579 (6)° | T = 293 K |
β = 103.326 (6)° | Needle, colorless |
γ = 106.552 (6)° | 0.21 × 0.12 × 0.04 mm |
V = 365.75 (5) Å3 |
Stoe IPSD-2 diffractometer | 1957 independent reflections |
Radiation source: fine-focus sealed tube | 1727 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
ω scan | θmax = 29.2°, θmin = 3.2° |
Absorption correction: numerical (X-SHAPE and X-RED32; Stoe & Cie, 2008) | h = −9→9 |
Tmin = 0.886, Tmax = 0.974 | k = −9→9 |
6973 measured reflections | l = −12→12 |
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)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.080 | H-atom parameters constrained |
S = 1.01 | w = 1/[σ2(Fo2) + (0.0352P)2 + 0.2734P] where P = (Fo2 + 2Fc2)/3 |
1957 reflections | (Δ/σ)max < 0.001 |
103 parameters | Δρmax = 0.43 e Å−3 |
0 restraints | Δρmin = −0.43 e Å−3 |
[Mg(C6H14N2O6P2)(H2O)4]·0.5H2O | γ = 106.552 (6)° |
Mr = 377.51 | V = 365.75 (5) Å3 |
Triclinic, P1 | Z = 1 |
a = 6.6296 (5) Å | Mo Kα radiation |
b = 6.8074 (6) Å | µ = 0.40 mm−1 |
c = 8.7962 (7) Å | T = 293 K |
α = 94.579 (6)° | 0.21 × 0.12 × 0.04 mm |
β = 103.326 (6)° |
Stoe IPSD-2 diffractometer | 1957 independent reflections |
Absorption correction: numerical (X-SHAPE and X-RED32; Stoe & Cie, 2008) | 1727 reflections with I > 2σ(I) |
Tmin = 0.886, Tmax = 0.974 | Rint = 0.036 |
6973 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.080 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.43 e Å−3 |
1957 reflections | Δρmin = −0.43 e Å−3 |
103 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 | Occ. (<1) | |
Mg1 | 0.5000 | 0.5000 | 0.5000 | 0.01868 (16) | |
P1 | 0.36611 (6) | 0.83891 (6) | 0.71790 (4) | 0.01741 (10) | |
O1 | 0.47100 (19) | 0.67534 (18) | 0.69031 (14) | 0.0256 (2) | |
O2 | 0.22643 (18) | 0.87610 (17) | 0.56605 (13) | 0.0228 (2) | |
O3 | 0.52336 (14) | 1.04094 (13) | 0.81824 (11) | 0.0225 (2) | |
C1 | 0.17809 (14) | 0.73201 (13) | 0.83666 (11) | 0.0218 (3) | |
H1A | 0.2264 | 0.6279 | 0.8904 | 0.026* | |
H1B | 0.0379 | 0.6240 | 0.8034 | 0.026* | |
N1 | 0.1348 (2) | 0.89184 (19) | 0.94153 (15) | 0.0181 (2) | |
H1N1 | 0.2589 | 0.9558 | 1.0077 | 0.022* | |
C2 | 0.0614 (3) | 1.0529 (2) | 0.85892 (19) | 0.0235 (3) | |
H2A | −0.0754 | 0.9870 | 0.7791 | 0.028* | |
H2B | 0.1690 | 1.1225 | 0.8065 | 0.028* | |
C3 | −0.0313 (3) | 0.7900 (2) | 1.02369 (19) | 0.0218 (3) | |
H3A | 0.0147 | 0.6857 | 1.0786 | 0.026* | |
H3B | −0.1695 | 0.7211 | 0.9461 | 0.026* | |
O4 | 0.30950 (18) | 0.64149 (17) | 0.34463 (13) | 0.0236 (2) | |
H1O4 | 0.3778 | 0.7291 | 0.3008 | 0.028* | |
H2O4 | 0.2647 | 0.7153 | 0.3980 | 0.028* | |
O5 | 0.22487 (19) | 0.26098 (18) | 0.51161 (16) | 0.0309 (3) | |
H1O5 | 0.2383 | 0.1488 | 0.5310 | 0.037* | |
H2O5 | 0.0957 | 0.2540 | 0.4922 | 0.037* | |
O6 | 0.5116 (13) | 0.5606 (12) | 1.0711 (9) | 0.0620 (19) | 0.25 |
H1O6 | 0.5284 | 0.5120 | 1.1538 | 0.093* | 0.25 |
H2O6 | 0.5205 | 0.6822 | 1.0956 | 0.093* | 0.25 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Mg1 | 0.0172 (3) | 0.0181 (3) | 0.0219 (3) | 0.0073 (3) | 0.0059 (3) | 0.0011 (3) |
P1 | 0.01580 (17) | 0.01772 (18) | 0.01999 (19) | 0.00653 (13) | 0.00637 (13) | 0.00069 (13) |
O1 | 0.0300 (6) | 0.0285 (6) | 0.0246 (6) | 0.0176 (5) | 0.0094 (5) | 0.0020 (4) |
O2 | 0.0203 (5) | 0.0246 (5) | 0.0244 (5) | 0.0097 (4) | 0.0047 (4) | 0.0025 (4) |
O3 | 0.0200 (5) | 0.0213 (5) | 0.0237 (5) | 0.0037 (4) | 0.0053 (4) | 0.0010 (4) |
C1 | 0.0228 (7) | 0.0170 (6) | 0.0276 (8) | 0.0055 (5) | 0.0121 (6) | 0.0011 (6) |
N1 | 0.0151 (5) | 0.0194 (6) | 0.0206 (6) | 0.0052 (4) | 0.0070 (5) | 0.0019 (5) |
C2 | 0.0269 (7) | 0.0258 (7) | 0.0246 (7) | 0.0132 (6) | 0.0127 (6) | 0.0077 (6) |
C3 | 0.0216 (7) | 0.0205 (7) | 0.0271 (7) | 0.0066 (6) | 0.0129 (6) | 0.0060 (6) |
O4 | 0.0245 (5) | 0.0233 (5) | 0.0252 (6) | 0.0101 (4) | 0.0075 (4) | 0.0032 (4) |
O5 | 0.0186 (5) | 0.0240 (6) | 0.0501 (8) | 0.0059 (4) | 0.0086 (5) | 0.0106 (5) |
O6 | 0.065 (5) | 0.059 (4) | 0.068 (5) | 0.025 (4) | 0.019 (4) | 0.020 (4) |
Mg1—O1i | 2.0552 (11) | N1—H1N1 | 0.8600 |
Mg1—O1 | 2.0553 (11) | C2—C3ii | 1.513 (2) |
Mg1—O5 | 2.0991 (12) | C2—H2A | 0.9700 |
Mg1—O5i | 2.0992 (12) | C2—H2B | 0.9700 |
Mg1—O4i | 2.1209 (11) | C3—C2ii | 1.513 (2) |
Mg1—O4 | 2.1209 (11) | C3—H3A | 0.9700 |
P1—O1 | 1.5027 (11) | C3—H3B | 0.9700 |
P1—O2 | 1.5242 (12) | O4—H1O4 | 0.8199 |
P1—O3 | 1.5240 (10) | O4—H2O4 | 0.8201 |
P1—C1 | 1.8383 | O5—H1O5 | 0.8200 |
C1—N1 | 1.5022 (15) | O5—H2O5 | 0.8200 |
C1—H1A | 0.9700 | O6—O6iii | 1.395 (16) |
C1—H1B | 0.9700 | O6—H1O6 | 0.8201 |
N1—C3 | 1.4925 (18) | O6—H2O6 | 0.8200 |
N1—C2 | 1.495 (2) | ||
O1i—Mg1—O1 | 180.00 (6) | C3—N1—C2 | 108.49 (11) |
O1i—Mg1—O5 | 90.35 (5) | C3—N1—C1 | 110.46 (10) |
O1—Mg1—O5 | 89.65 (5) | C2—N1—C1 | 114.75 (11) |
O1i—Mg1—O5i | 89.65 (5) | C3—N1—H1N1 | 111.5 |
O1—Mg1—O5i | 90.35 (5) | C2—N1—H1N1 | 106.5 |
O5—Mg1—O5i | 180.00 (7) | C1—N1—H1N1 | 105.1 |
O1i—Mg1—O4i | 89.80 (4) | N1—C2—C3ii | 110.27 (12) |
O1—Mg1—O4i | 90.20 (4) | N1—C2—H2A | 109.6 |
O5—Mg1—O4i | 87.19 (5) | C3ii—C2—H2A | 109.6 |
O5i—Mg1—O4i | 92.81 (5) | N1—C2—H2B | 109.6 |
O1i—Mg1—O4 | 90.20 (4) | C3ii—C2—H2B | 109.6 |
O1—Mg1—O4 | 89.80 (4) | H2A—C2—H2B | 108.1 |
O5—Mg1—O4 | 92.81 (5) | N1—C3—C2ii | 111.06 (12) |
O5i—Mg1—O4 | 87.19 (5) | N1—C3—H3A | 109.4 |
O4i—Mg1—O4 | 180.0 | C2ii—C3—H3A | 109.4 |
O1—P1—O2 | 113.06 (7) | N1—C3—H3B | 109.4 |
O1—P1—O3 | 114.25 (6) | C2ii—C3—H3B | 109.4 |
O2—P1—O3 | 112.00 (6) | H3A—C3—H3B | 108.0 |
O1—P1—C1 | 105.10 (6) | Mg1—O4—H1O4 | 115.4 |
O2—P1—C1 | 106.31 (6) | Mg1—O4—H2O4 | 108.1 |
O3—P1—C1 | 105.20 (5) | H1O4—O4—H2O4 | 99.6 |
P1—O1—Mg1 | 137.40 (7) | Mg1—O5—H1O5 | 119.2 |
N1—C1—P1 | 114.69 (7) | Mg1—O5—H2O5 | 130.9 |
N1—C1—H1A | 114.7 | H1O5—O5—H2O5 | 109.7 |
P1—C1—H1A | 108.7 | O6iii—O6—H1O6 | 119.9 |
N1—C1—H1B | 102.6 | O6iii—O6—H2O6 | 133.7 |
P1—C1—H1B | 128.8 | H1O6—O6—H2O6 | 106.3 |
H1A—C1—H1B | 83.9 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y+2, −z+2; (iii) −x+1, −y+1, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O3iv | 0.86 | 1.84 | 2.6187 (16) | 150 |
O4—H1O4···O3v | 0.82 | 1.99 | 2.7956 (15) | 166 |
O4—H2O4···O2 | 0.82 | 1.88 | 2.6733 (17) | 164 |
O5—H1O5···O2vi | 0.82 | 1.89 | 2.7032 (17) | 172 |
O5—H2O5···O2vii | 0.82 | 1.99 | 2.7667 (18) | 158 |
C1—H1B···O4vii | 0.97 | 2.48 | 3.4279 (15) | 166 |
C2—H2B···O3 | 0.97 | 2.55 | 3.187 (2) | 124 |
Symmetry codes: (iv) −x+1, −y+2, −z+2; (v) −x+1, −y+2, −z+1; (vi) x, y−1, z; (vii) −x, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | [Mg(C6H14N2O6P2)(H2O)4]·0.5H2O |
Mr | 377.51 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 6.6296 (5), 6.8074 (6), 8.7962 (7) |
α, β, γ (°) | 94.579 (6), 103.326 (6), 106.552 (6) |
V (Å3) | 365.75 (5) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 0.40 |
Crystal size (mm) | 0.21 × 0.12 × 0.04 |
Data collection | |
Diffractometer | Stoe IPSD-2 diffractometer |
Absorption correction | Numerical (X-SHAPE and X-RED32; Stoe & Cie, 2008) |
Tmin, Tmax | 0.886, 0.974 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6973, 1957, 1727 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.686 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.080, 1.01 |
No. of reflections | 1957 |
No. of parameters | 103 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.43, −0.43 |
Computer programs: X-AREA (Stoe & Cie, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008) and DIAMOND Brandenburg (2011);, XCIF in SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O3i | 0.86 | 1.84 | 2.6187 (16) | 150 |
O4—H1O4···O3ii | 0.82 | 1.99 | 2.7956 (15) | 166 |
O4—H2O4···O2 | 0.82 | 1.88 | 2.6733 (17) | 164 |
O5—H1O5···O2iii | 0.82 | 1.89 | 2.7032 (17) | 172 |
O5—H2O5···O2iv | 0.82 | 1.99 | 2.7667 (18) | 158 |
C1—H1B···O4iv | 0.97 | 2.48 | 3.4279 (15) | 166 |
C2—H2B···O3 | 0.97 | 2.55 | 3.187 (2) | 124 |
Symmetry codes: (i) −x+1, −y+2, −z+2; (ii) −x+1, −y+2, −z+1; (iii) x, y−1, z; (iv) −x, −y+1, −z+1. |
Acknowledgements
We gratefully acknowledge financial support by the DFG (project No. STO-643/2–3) and the State of Schleswig–Holstein.
References
Brandenburg, K. (2011). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Choi, N., Khan, I., Matthews, R. W., McPartlin, M. & Murphy, B. P. (1994). Polyhedron, 13, 847–850. CSD CrossRef CAS Web of Science Google Scholar
Gagnon, K. J., Perry, H. P. & Clearfield, A. (2012). Chem. Rev. 112, 1034–1054. Web of Science CrossRef CAS PubMed Google Scholar
Groves, J. A., Miller, S. R., Warrender, S. J., Mellot-Draznieks, C., Lightfoot, P. & Wright, P. A. (2006). Chem. Commun. pp. 3305–3307. Web of Science CSD CrossRef Google Scholar
Groves, J. A., Stephens, N. F., Wright, P. A. & Lightfoot, P. (2006). Solid State Sci. 8, 397–403. Web of Science CSD CrossRef CAS Google Scholar
Groves, J. A., Wright, P. A. & Lightfoot, P. (2005a). Dalton Trans. pp. 2007–2010. Web of Science CSD CrossRef PubMed Google Scholar
Groves, J. A., Wright, P. A. & Lightfoot, P. (2005b). Inorg. Chem. 44, 1736–1739. Web of Science CSD CrossRef PubMed CAS Google Scholar
LaDuca, R., Rose, D., DeBord, J. R. D., Haushalter, R. C., O'Connor, C. J. & Zubieta, J. (1996). J. Solid State Chem. 123, 408–412. CSD CrossRef CAS Web of Science Google Scholar
Serre, C., Groves, J. A., Lightfoot, P., Slawin, A. M. Z., Wright, P. A., Stock, N., Bein, T., Haouas, M., Taulelle, F. & Férey, G. R. (2006). Chem. Mater. 18, 1451–1457. Web of Science CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Soghomonian, V., Diaz, R., Haushalter, R. C., O'Connor, C. J. & Zubieta, J. (1995). Inorg. Chem. 34, 4460–4466. CSD CrossRef CAS Web of Science Google Scholar
Stoe & Cie (2008). X-AREA, X-RED32 and X-SHAPE. Stoe & Cie, Darmstadt, Germany. Google Scholar
Wang, Y., Bao, S.-S., Xu, W., Chen, J., Gao, S. & Zheng, L.-M. (2004). J. Solid State Chem. 177, 1297–1301. Web of Science CSD CrossRef CAS Google Scholar
Wharmby, M. T., Pearce, G. M., Mowat, J. P. S., Griffin, J. M., Ashbrook, S. E., Wright, P. A., Schilling, L.-H., Lieb, A., Stock, N., Chavan, S., Bordiga, S., Garcia, E., Pirngruber, G. D., Vreeke, M. & Gora, L. (2012). Microporous Mesoporous Mater. 157, 3–17. Web of Science CSD CrossRef CAS Google Scholar
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.
Due to their flexible coordination behaviour, organic linker molecules containing phosphonate groups allow the synthesis of a multitude of inorganic-organic hybrid materials (Gagnon et al., 2012). In this context, the ligand N,N'-piperazinebis(methylenephosphonic acid) (H2O3P—CH2—NC4H8N—CH2—PO3H2 = H4L) has been the subject of intense interest, since its use has led to a number of dense metal phosphonates (Groves, Stephens et al., 2006, Groves et al., 2005a, 2005b, Choi et al., 1994, LaDuca et al., 1996, Soghomonian et al., 1995, Wang et al., 2004) as well as porous ones (Groves, Miller et al., 2006, Serre et al., 2006). The compounds [Co2(H2O)2L] . 5.1 H2O (denoted Co-STA-12) and [Mg2(H2O)2L] . 3.97 H2O (denoted CAU-2) are highly porous with micropore volumes of 0.14 cm3 g-1 and 0.20 cm3 g-1, respectively (Wharmby et al., 2012). Investigation of the system MgCl2 . 6 H2O / H4L / base / H2O led to the formation of CAU-2. We have now been able to isolate a new compound, [Mg(H2O)4(H2L)] . 0.5 H2O, in this system, which is obtained from slightly acidic reaction mixtures (4 ≤ pH ≤ 6.5). Optimization of the reaction conditions (concentration and reaction time) led to the formation of single crystals. The asymmetric unit of the crystal structure is depicted in Fig. 1.
[Mg(H2O)4(H2L)] . 0.5 H2O adopts a one-dimensional structure containing alternating inorganic and organic building units of MgO6 polyhedra and N,N'-piperaziniumbis(methylenephosphonate) ions (Fig. 2). The Mg2+ ions are octahedrally coordinated by six oxygen atoms (O1, O4, O5 and their symmetry equivalents), of which four (O4 and O5) belong to water molecules while two (O1) belong to phosphonate groups of the ligand molecules. The charge of the structure is balanced by protons connected to the N atoms of the ligand making it a quaternary amine. In addition, a further water molecule is found on a partially occupied position.