The crystal structure of magnesium copper(II) bis[orthophosphate(V)] monohydrate is formed by three types of cationic sites and by two unique (PO4)3− anions. One site is occupied by Cu2+, the second site by Mg2+and the third site by a mixture of the two cations with an Mg2+:Cu2+ occupancy ratio of 0.657 (3):0.343 (3).
Keywords: crystal structure, magnesium copper(II) bis[orthophosphate(V)] monohydrate, hydrogen bonding, transition metal phosphates, hydrothermal synthesis
Abstract
Single crystals of magnesium copper(II) bis[orthophosphate(V)] monohydrate, Mg1.65Cu1.35(PO4)2·H2O, were grown under hydrothermal conditions. The crystal structure is formed by three types of cationic sites and by two unique (PO4)3− anions. One site is occupied by Cu2+, the second site by Mg2+and the third site by a mixture of the two cations with an Mg2+:Cu2+ occupancy ratio of 0.657 (3):0.343 (3). The structure is built up from more or less distorted [MgO6] and [(Mg/Cu)O5(H2O)] octahedra, [CuO5] square-pyramids and regular PO4 tetrahedra, leading to a framework structure. Within this framework, two types of layers parallel to (-101) can be distinguished. The first layer is formed by [Cu2O8] dimers linked to PO4 tetrahedra via common edges. The second, more corrugated layer results from the linkage between [(Cu/Mg)2O8(H2O)2] dimers and [MgO6] octahedra by common edges. The PO4 units link the two types of layers, leaving space for channels parallel [101], into which the H atoms of the water molecules protrude. The latter are involved in O—H⋯O hydrogen-bonding interactions (one bifurcated) with framework O atoms across the channels.
Chemical context
Transition metal phosphates are an important class of materials characterized by a great structural diversity originating from the presence of different coordination polyhedra MOn (with n = 4, 5 and 6) or the possibility of phosphate groups to condense. The alternation of PO4 tetrahedra and MOn polyhedra can give rise to different anionic frameworks [M IIPO4]− with pores or channels offering suitable environments to accommodate different other cations (Gao & Gao, 2005 ▸; Viter & Nagornyi, 2009 ▸). In previous studies, our focus of research was dedicated to the examination of mixed divalent orthophosphates with general formula (M,M′)3(PO4)2·nH2O. For instance, we have succeeded in the preparation and structure determination of some new phosphates such as Ni2Sr(PO4)2·2H2O (Assani et al., 2010a ▸).
In the context of our main research, we report here the hydrothermal synthesis and structural characterization of the mixed-metal orthophosphate Mg1.65Cu1.35(PO4)2·H2O, isolated during investigation of the quinternary system Ag2O/MgO/CuO/P2O5/H2O. The title compound crystallizes in the Fe3(PO4)2·H2O structure type (Moore & Araki, 1975 ▸) and is isotypic with other phases of the type (M,M’)3(PO4)2·H2O (Liao et al., 1995 ▸), viz. Co2.59Zn0.41(PO4)2·H2O (Sørensen et al., 2005 ▸), Co2.39Cu0.61(PO4)2·H2O (Assani et al., 2010b ▸), (Cu1−xCox)3(PO4)2·H2O (0 < x < 0.20 and 0.55 < x < 0.65), and (Cu1−xZnx)3(PO4)2·H2O (0 < x < 0.19) (Viter & Nagornyi, 2006 ▸).
Structural commentary
The principal building units of the crystal structure of the title compound are represented in Fig. 1 ▸. The metal cations are located in three crystallographically independent sites, one octahedrally surrounded site entirely occupied by Mg2+, one site with a square-pyramidal coordination completely occupied by Cu2+ and one mixed-occupied (Mg2+/Cu2+) site with an octahedral coordination. The [Cu1O5] square pyramid is distorted, with Cu—O bond lengths ranging from 1.9073 (17) to 2.2782 (16) Å. Two [Cu1O5] polyhedra are linked together by edge-sharing to build up a [Cu2O8] dimer. By sharing corners with PO4 tetrahedra, a layered arrangement parallel to (
01) is formed (Fig. 2 ▸). The mixed-occupied [(Mg/Cu)O5(H2O)] octahedron is likewise distorted, with (Mg/Cu)—O distances varying between 2.0038 (18) and 2.384 (2) Å. Two [(Mg/Cu)O5(H2O)] octahedra share a common edge to built up another dimer [(Mg/Cu)2O8(H2O)2] that links [MgO6] octahedra and PO4 tetrahedra via common vertices to build the second type of layer lying parallel to the first (Fig. 2 ▸). Adjacent layers are connected into a three-dimensional framework by common edges and vertices, and delimit channels parallel to [101], into which the hydrogen atoms of the water molecules protrude. O—H⋯O hydrogen-bonding interactions between the water molecules and framework O atoms are present (Table 1 ▸, Fig. 2 ▸).
Figure 1.
The principal building units in the crystal structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: x − 
, −y + , z − ; (ii) −x + 1, −y + 1, −z + 1; (iii) −x + 2, −y + 1, −z + 1; (iv) x + , −y + 
, z + ; (v) −x + , y + , −z + ; (vi) −x + 2, −y + 1, −z + 2; (vii) −x + , y + , −z + ; (viii) −x + 2, −y + 2, −z + 1.]
Figure 2.
A polyhedral view of the title compound, showing the three-dimensional framework structure and O—H⋯O hydrogen bonding (dashed lines) in the channels.
Table 1. Hydrogen-bond geometry (, ).
| DHA | DH | HA | D A | DHA |
|---|---|---|---|---|
| O9H9AO1i | 0.86 | 2.22 | 2.867(2) | 132 |
| O9H9AO6ii | 0.86 | 2.38 | 2.934(2) | 123 |
| O9H9BO8iii | 0.86 | 1.93 | 2.778(2) | 170 |
Symmetry codes: (i) 
; (ii) 
; (iii) 
.
Synthesis and crystallization
The title compound, Mg1.65Cu1.35(PO4)2·H2O, was synthesized hydrothermally form a reaction mixture of AgNO3, MgO, metallic copper, and 85wt% phosphoric acid in the molar ratio Ag: Mg: Cu: P = 1: 4: 4.5: 6 in 12.5 ml of water. The hydrothermal reaction was conducted in a 23 ml Teflon-lined autoclave under autogenous pressure at 493 K for three days. The resulting product was filtered off, washed with deionized water and dried in air. The obtained blue crystals correspond to the title compound.
Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The M2 site features mixed occupation by Mg2+ and Cu2+ whereas the other two cationic sites do not show any significant disorder. Refinement of the occupancy of M2 resulted in a ratio of Mg2+:Cu2+ = 0.657 (3):0.343 (3). The O-bound H atoms were initially located in a difference map and refined with O—H distance restraints of 0.83 (5). In the last refinement cycle, the distances were fixed at 0.86 Å and the H atoms refined in the riding-model approximation with U iso(H) set to 1.5U eq(O). The highest remaining positive and negative electron densities observed in the final Fourier map are at 0.81 Å and 0.43 Å, respectively, from Cu1.
Table 2. Experimental details.
| Crystal data | |
| Chemical formula | Mg1.65Cu1.35(PO4)2H2O |
| M r | 333.65 |
| Crystal system, space group | Monoclinic, P21/n |
| Temperature (K) | 296 |
| a, b, c () | 8.0701(1), 9.8661(2), 8.9944(2) |
| () | 115.242(1) |
| V (3) | 647.76(2) |
| Z | 4 |
| Radiation type | Mo K |
| (mm1) | 5.16 |
| Crystal size (mm) | 0.31 0.27 0.18 |
| Data collection | |
| Diffractometer | Bruker X8 APEX |
| Absorption correction | Multi-scan (SADABS; Bruker, 2009 ▸) |
| T min, T max | 0.574, 0.748 |
| No. of measured, independent and observed [I > 2(I)] reflections | 9233, 1673, 1617 |
| R int | 0.025 |
| (sin /)max (1) | 0.676 |
| Refinement | |
| R[F 2 > 2(F 2)], wR(F 2), S | 0.020, 0.058, 1.24 |
| No. of reflections | 1673 |
| No. of parameters | 129 |
| H-atom treatment | H-atom parameters constrained |
| max, min (e 3) | 0.55, 0.34 |
Supplementary Material
Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989014026930/wm5097sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989014026930/wm5097Isup2.hkl
CCDC reference: 1038224
Additional supporting information: crystallographic information; 3D view; checkCIF report
Acknowledgments
The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements and the University Mohammed V, Rabat, Morocco, for financial support.
supplementary crystallographic information
Crystal data
| Mg1.65Cu1.35(PO4)2·H2O | F(000) = 651 |
| Mr = 333.65 | Dx = 3.421 Mg m−3 |
| Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -p 2yn | Cell parameters from 1673 reflections |
| a = 8.0701 (1) Å | θ = 2.9–28.7° |
| b = 9.8661 (2) Å | µ = 5.16 mm−1 |
| c = 8.9944 (2) Å | T = 296 K |
| β = 115.242 (1)° | Prism, blue |
| V = 647.76 (2) Å3 | 0.31 × 0.27 × 0.18 mm |
| Z = 4 |
Data collection
| Bruker X8 APEX diffractometer | 1673 independent reflections |
| Radiation source: fine-focus sealed tube | 1617 reflections with I > 2σ(I) |
| Graphite monochromator | Rint = 0.025 |
| φ and ω scans | θmax = 28.7°, θmin = 2.9° |
| Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −10→10 |
| Tmin = 0.574, Tmax = 0.748 | k = −11→13 |
| 9233 measured reflections | l = −12→12 |
Refinement
| 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) = 0.058 | w = 1/[σ2(Fo2) + (0.0209P)2 + 1.2623P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.24 | (Δ/σ)max = 0.001 |
| 1673 reflections | Δρmax = 0.55 e Å−3 |
| 129 parameters | Δρmin = −0.34 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: 0.0022 (6) |
Special details
| 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 > 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)
| x | y | z | Uiso*/Ueq | Occ. (<1) | |
| Cu1 | 0.64417 (4) | 0.37312 (3) | 0.56030 (3) | 0.00781 (10) | |
| Mg1 | 0.98357 (10) | 0.62883 (7) | 0.72316 (9) | 0.00506 (16) | |
| Cu2 | 0.88601 (7) | 0.86606 (5) | 0.46685 (6) | 0.00771 (19) | 0.343 (3) |
| Mg2 | 0.88601 (7) | 0.86606 (5) | 0.46685 (6) | 0.00771 (19) | 0.657 (3) |
| P1 | 0.70807 (7) | 0.57775 (6) | 0.32947 (7) | 0.00456 (13) | |
| P2 | 0.88138 (7) | 0.33721 (6) | 0.86197 (7) | 0.00517 (13) | |
| O1 | 0.5825 (2) | 0.51553 (17) | 0.4023 (2) | 0.0088 (3) | |
| O4 | 0.8713 (2) | 0.64903 (17) | 0.4655 (2) | 0.0092 (3) | |
| O3 | 0.5882 (2) | 0.68080 (16) | 0.19945 (19) | 0.0068 (3) | |
| O2 | 0.7722 (2) | 0.46440 (16) | 0.2486 (2) | 0.0071 (3) | |
| O5 | 0.8579 (2) | 0.36647 (17) | 1.0187 (2) | 0.0088 (3) | |
| O6 | 0.7227 (2) | 0.24356 (17) | 0.7487 (2) | 0.0081 (3) | |
| O7 | 0.8521 (2) | 0.46259 (17) | 0.75021 (19) | 0.0078 (3) | |
| O8 | 1.0684 (2) | 0.27408 (17) | 0.9037 (2) | 0.0094 (3) | |
| O9 | 1.1046 (2) | 0.9118 (2) | 0.4255 (2) | 0.0139 (4) | |
| H9A | 1.0944 | 0.9060 | 0.3265 | 0.021* | |
| H9B | 1.2106 | 0.8782 | 0.4857 | 0.021* |
Atomic displacement parameters (Å2)
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cu1 | 0.01066 (15) | 0.00588 (15) | 0.00473 (15) | −0.00143 (9) | 0.00122 (11) | 0.00069 (9) |
| Mg1 | 0.0054 (3) | 0.0042 (3) | 0.0049 (3) | −0.0001 (2) | 0.0016 (3) | 0.0003 (3) |
| Cu2 | 0.0060 (3) | 0.0097 (3) | 0.0068 (3) | 0.00074 (16) | 0.00216 (19) | 0.00187 (17) |
| Mg2 | 0.0060 (3) | 0.0097 (3) | 0.0068 (3) | 0.00074 (16) | 0.00216 (19) | 0.00187 (17) |
| P1 | 0.0056 (2) | 0.0043 (3) | 0.0034 (2) | 0.00024 (18) | 0.00156 (19) | −0.00019 (18) |
| P2 | 0.0064 (2) | 0.0046 (2) | 0.0041 (2) | −0.00022 (19) | 0.00177 (19) | 0.00026 (19) |
| O1 | 0.0092 (7) | 0.0097 (8) | 0.0091 (7) | 0.0016 (6) | 0.0054 (6) | 0.0036 (6) |
| O4 | 0.0084 (7) | 0.0097 (8) | 0.0062 (7) | −0.0017 (6) | −0.0001 (6) | −0.0025 (6) |
| O3 | 0.0088 (7) | 0.0052 (7) | 0.0050 (7) | 0.0016 (6) | 0.0017 (6) | 0.0011 (6) |
| O2 | 0.0084 (7) | 0.0061 (7) | 0.0064 (7) | 0.0022 (6) | 0.0027 (6) | −0.0014 (6) |
| O5 | 0.0111 (8) | 0.0102 (8) | 0.0053 (7) | −0.0004 (6) | 0.0036 (6) | −0.0014 (6) |
| O6 | 0.0091 (7) | 0.0078 (7) | 0.0060 (7) | −0.0027 (6) | 0.0019 (6) | 0.0005 (6) |
| O7 | 0.0083 (7) | 0.0056 (7) | 0.0071 (7) | −0.0014 (6) | 0.0011 (6) | 0.0021 (6) |
| O8 | 0.0086 (7) | 0.0099 (8) | 0.0094 (8) | 0.0025 (6) | 0.0035 (6) | 0.0030 (6) |
| O9 | 0.0085 (7) | 0.0256 (10) | 0.0073 (8) | 0.0035 (7) | 0.0032 (6) | 0.0045 (7) |
Geometric parameters (Å, º)
| Cu1—O1 | 1.9073 (17) | Cu2—O3iv | 2.0837 (16) |
| Cu1—O8i | 1.9322 (17) | Cu2—O4 | 2.1442 (18) |
| Cu1—O6 | 1.9980 (16) | Cu2—O9viii | 2.384 (2) |
| Cu1—O7 | 2.0169 (16) | P1—O4 | 1.5340 (17) |
| Cu1—O1ii | 2.2782 (16) | P1—O2 | 1.5392 (16) |
| Mg1—O7 | 2.0236 (18) | P1—O3 | 1.5401 (16) |
| Mg1—O2iii | 2.0898 (17) | P1—O1 | 1.5491 (17) |
| Mg1—O4 | 2.1070 (18) | P2—O8 | 1.5241 (17) |
| Mg1—O3iv | 2.1071 (17) | P2—O5 | 1.5279 (17) |
| Mg1—O6v | 2.1156 (17) | P2—O7 | 1.5473 (17) |
| Mg1—O5vi | 2.1205 (18) | P2—O6 | 1.5550 (17) |
| Cu2—O9 | 2.0038 (18) | O9—H9A | 0.8600 |
| Cu2—O5v | 2.0268 (17) | O9—H9B | 0.8600 |
| Cu2—O2vii | 2.0535 (17) | ||
| O1—Cu1—O8i | 96.29 (7) | O5v—Cu2—O2vii | 80.18 (7) |
| O1—Cu1—O6 | 172.25 (7) | O9—Cu2—O3iv | 82.06 (7) |
| O8i—Cu1—O6 | 91.43 (7) | O5v—Cu2—O3iv | 107.59 (7) |
| O1—Cu1—O7 | 99.62 (7) | O2vii—Cu2—O3iv | 163.32 (7) |
| O8i—Cu1—O7 | 146.81 (7) | O9—Cu2—O4 | 105.96 (8) |
| O6—Cu1—O7 | 73.33 (7) | O5v—Cu2—O4 | 87.11 (7) |
| O1—Cu1—O1ii | 77.52 (7) | O2vii—Cu2—O4 | 117.13 (7) |
| O8i—Cu1—O1ii | 116.46 (6) | O3iv—Cu2—O4 | 78.56 (6) |
| O6—Cu1—O1ii | 99.65 (6) | O9—Cu2—O9viii | 89.45 (7) |
| O7—Cu1—O1ii | 95.41 (6) | O5v—Cu2—O9viii | 80.53 (6) |
| O7—Mg1—O2iii | 98.29 (7) | O2vii—Cu2—O9viii | 81.28 (6) |
| O7—Mg1—O4 | 101.96 (7) | O3iv—Cu2—O9viii | 85.44 (6) |
| O2iii—Mg1—O4 | 96.67 (7) | O4—Cu2—O9viii | 155.82 (7) |
| O7—Mg1—O3iv | 171.09 (8) | O4—P1—O2 | 111.26 (9) |
| O2iii—Mg1—O3iv | 90.39 (7) | O4—P1—O3 | 110.54 (9) |
| O4—Mg1—O3iv | 78.89 (7) | O2—P1—O3 | 110.47 (9) |
| O7—Mg1—O6v | 86.54 (7) | O4—P1—O1 | 109.79 (9) |
| O2iii—Mg1—O6v | 166.01 (7) | O2—P1—O1 | 108.93 (9) |
| O4—Mg1—O6v | 95.14 (7) | O3—P1—O1 | 105.69 (9) |
| O3iv—Mg1—O6v | 84.55 (7) | O8—P2—O5 | 110.47 (9) |
| O7—Mg1—O5vi | 89.35 (7) | O8—P2—O7 | 110.33 (9) |
| O2iii—Mg1—O5vi | 77.24 (7) | O5—P2—O7 | 113.81 (9) |
| O4—Mg1—O5vi | 167.90 (8) | O8—P2—O6 | 111.75 (10) |
| O3iv—Mg1—O5vi | 90.60 (7) | O5—P2—O6 | 108.96 (9) |
| O6v—Mg1—O5vi | 89.76 (7) | O7—P2—O6 | 101.22 (9) |
| O9—Cu2—O5v | 165.32 (8) | H9A—O9—H9B | 104.9 |
| O9—Cu2—O2vii | 87.74 (7) |
Symmetry codes: (i) x−1/2, −y+1/2, z−1/2; (ii) −x+1, −y+1, −z+1; (iii) −x+2, −y+1, −z+1; (iv) x+1/2, −y+3/2, z+1/2; (v) −x+3/2, y+1/2, −z+3/2; (vi) −x+2, −y+1, −z+2; (vii) −x+3/2, y+1/2, −z+1/2; (viii) −x+2, −y+2, −z+1.
Hydrogen-bond geometry (Å, º)
| D—H···A | D—H | H···A | D···A | D—H···A |
| O9—H9A···O1vii | 0.86 | 2.22 | 2.867 (2) | 132 |
| O9—H9A···O6iii | 0.86 | 2.38 | 2.934 (2) | 123 |
| O9—H9B···O8ix | 0.86 | 1.93 | 2.778 (2) | 170 |
Symmetry codes: (iii) −x+2, −y+1, −z+1; (vii) −x+3/2, y+1/2, −z+1/2; (ix) −x+5/2, y+1/2, −z+3/2.
References
- Assani, A., Saadi, M. & El Ammari, L. (2010a). Acta Cryst. E66, i44. [DOI] [PMC free article] [PubMed]
- Assani, A., Saadi, M., Zriouil, M. & El Ammari, L. (2010b). Acta Cryst. E66, i86–i87. [DOI] [PMC free article] [PubMed]
- Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.
- Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
- Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.
- Gao, D. & Gao, Q. (2005). Micropor. Mesopor. Mater. 85, 365–373.
- Liao, J. H., Leroux, F., Guyomard, D., Piffard, Y. & Tournoux, M. (1995). Eur. J. Solid State Inorg. Chem. 32, 403–414.
- Moore, P. B. & Araki, T. (1975). Am. Mineral. 60, 454–459.
- Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [DOI] [PubMed]
- Sørensen, M. B., Hazell, R. G., Bentien, A., Bond, A. D. & Jensen, T. R. (2005). Dalton Trans. pp. 598–606. [DOI] [PubMed]
- Viter, V. N. & Nagornyi, P. G. (2006). Inorg. Mater. 42, 406–409.
- Viter, V. N. & Nagornyi, P. G. (2009). Russ. J. Appl. Chem. 82, 935–939.
- Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989014026930/wm5097sup1.cif
Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989014026930/wm5097Isup2.hkl
CCDC reference: 1038224
Additional supporting information: crystallographic information; 3D view; checkCIF report