Dicaesium magnesium bis­(dihydrogen phosphate(V)) dihydrate

Essehli, R.; El Bali, B.; Lachkar, M.; Bolte, M.

doi:10.1107/S1600536808042384

inorganic compounds

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ISSN: 2056-9890

Volume 65| Part 1| January 2009| Page i3

doi:10.1107/S1600536808042384

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Dicaesium magnesium bis(dihydrogen phosphate(V)) dihydrate

Rachid Essehli,^a Brahim El Bali,^a ^* Mohammed Lachkar ^b and Michael Bolte ^c

^aDepartment of Chemistry, Faculty of Sciences, University Mohammed 1st, PO Box 717, 60 000 Oujda, Morocco, ^bLIMOM, Faculty of Sciences, University Sidi Mohamed Ben Abdellah, PO Box 1796 (Atlas), 30000 Fez, Morocco, and ^cInstitut für Anorganische Chemie, J. W. Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
^*Correspondence e-mail: belbali@fso.ump.ma

(Received 9 December 2008; accepted 12 December 2008; online 17 December 2008)

The title compound, Cs₂Mg(H₂P₂O₇)₂·2H₂O, is isostructural with the related known isoformular phosphates. The crystal framework consists of corner-sharing MgO₆ and H₂P₂O₇ polyhedra, leading to tunnels parallel to the b-axis direction in which Cs⁺ ions are located. The H₂P₂O₇ unit shows a bent eclipsed conformation. The Mg²⁺ ion lies on an inversion center. The water molecules form hydrogen bonds to O atoms of two different dihydrogenphosphate ions, which are further hydrogen bonded to symmetry-equivalent dihydrogenphosphate ions.

Related literature

For isostructural phosphates, see: Capitelli et al. (2004 ), (NH₄)₂Mn(H₂P₂O₇)₂·2H₂O; Essehli et al. (2005a ), (NH₄)₂Zn(H₂P₂O₇)₂·2H₂O; Essehli et al. (2005b ), (NH₄)₂Ni(H₂P₂O₇)₂·2H₂O; Essehli et al. (2005c ), (NH₄)₂Co(H₂P₂O₇)₂·2H₂O; Tahiri et al. (2004 ), K₂Ni(H₂P₂O₇)₂·2H₂O; Tahiri et al. (2003 ), K₂Zn(H₂P₂O₇)₂·2H₂O; Harcharras et al. (2003 ), K₂Mg(H₂P₂O₇)₂·2H₂O. For the biological activity of inorganic acidic diphosphates containing HP₂O₇³⁻ or H₂P₂O₇²⁻ anions, see: Andreeva et al. (2001 ).

Experimental

Crystal data

Cs₂Mg(H₂P₂O₇)₂·2H₂O
M_r = 678.07
Triclinic, $[P \overline 1]$
a = 7.0935 (15) Å
b = 7.4606 (15) Å
c = 8.0230 (15) Å
α = 83.776 (16)°
β = 68.558 (15)°
γ = 87.850 (17)°
V = 392.87 (14) Å³
Z = 1
Mo Kα radiation
μ = 5.17 mm⁻¹
T = 173 (2) K
0.19 × 0.15 × 0.08 mm

Data collection

Stoe IPDSII two-circle diffractometer
Absorption correction: multi-scan (MULABS; Spek, 2003 ; Blessing, 1995 ) T_min = 0.440, T_max = 0.683
3316 measured reflections
1420 independent reflections
1245 reflections with I > 2σ(I)
R_int = 0.082

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.125
S = 1.02
1420 reflections
115 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 2.00 e Å⁻³
Δρ_min = −2.73 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1WA⋯O1ⁱ	0.839 (10)	2.01 (4)	2.804 (8)	158 (9)
O1W—H1WB⋯O6ⁱⁱ	0.839 (10)	1.97 (3)	2.778 (9)	162 (9)
O3—H3⋯O6ⁱⁱ	0.84	1.72	2.551 (8)	172
O7—H7⋯O1ⁱⁱⁱ	0.84	1.71	2.518 (8)	159
Symmetry codes: (i) x, y, z+1; (ii) -x+1, -y, -z+1; (iii) x+1, y, z.

Data collection: X-AREA (Stoe & Cie, 2001 ); cell refinement: 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-Plus (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808042384/br2088sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808042384/br2088Isup2.hkl

checkCIF report

Comment top

Inorganic acidic diphosphates containing HP₂O₇ or H₂P₂O₇ hold important biochemical activities, such as inhibitors of human immunodeficiency enzymes as reported by Andreeva et al. (2001). In the framework of our systematic research on these phosphates, we report on the new compound Cs₂Mg(H₂P₂O₇)₂.2H₂O. Detailed studies on structure determinations of such phosphates are available in related crystallography literature.

The crystal packing of Cs₂Mg(H₂P₂O₇)₂.2H₂O is a 3D network made upon edges sharing [MgO₆] octahedra and dihydrogendiphosphate [H₂P₂O₇]. These delimite tunnels along b direction, where Cs⁺ ions are located. A projection onto ac-plan is depicted on Fig. 1.

Mg²⁺ cation sites are on inversion center. It is coordinated by four O atoms from two bidendate [H₂P₂O₇] groups and two remaining O atoms from water molecule (Fig. 2).

H₂P₂O₇ shows bent eclipsed conformation. Distances and angles in [MgO₆] and [H₂P₂O₇] are as usual as in related phosphates structures. The [MgO₆] are isolated in the structure, with an Mg-Mg distance over 7 Å.

Related literature top

For isostructural phosphates, see: Capitelli et al. (2004), (NH₄)₂Mn(H₂P₂O₇)₂.2H₂O; Essehli et al. (2005a), (NH₄)₂Zn(H₂P₂O₇)₂.2H₂O; Essehli et al. (2005b), (NH₄)₂Ni(H₂P₂O₇)₂.2H₂O; Essehli et al. (2005c), (NH₄)₂Co(H₂P₂O₇)₂.2H₂O; Tahiri et al. (2004), K₂Ni(H₂P₂O₇)₂.2H₂O; Tahiri et al. (2003), K₂Zn(H₂P₂O₇)₂.2H₂O; Harcharras et al. (2003), K₂Mg(H₂P₂O₇)₂.2H₂O. For the biological activity of inorganic acidic diphosphates containing HP₂O₇ or H₂P₂O₇, see: Andreeva et al. (2001); .

Experimental top

Crystals of Cs₂Mn(H₂P₂O₇)₂.2H₂O were grown at room temperature by slow evaporation from water-ethanol (80/20) of aqueous solution containing a stoichiometric the mixture : MgCl₂.6H₂O (0.231mg, 1mmol), Cs₂CO₃ (0.24mg, 1mmol), and K₄P₂O₇ (0.5mg, 1mmol). The solution was stirred for two hours at leaved to stand at room temperature. Crystals suitable for X-ray analysis were formed after few days.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Crystal structure of Cs₂Mn(H₂P₂O₇)₂.2H₂O viewed along b direction.
	Fig. 2. Mg coordination in Cs₂Mn(H₂P₂O₇)₂.2H₂O. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry code: (i) - x,- y, - z.

Dicaesium magnesium bis(dihydrogen phosphate) dihydrate top

Crystal data top

Cs₂Mg(H₂P₂O₇)₂·2H₂O	Z = 1
M_r = 678.07	F(000) = 318
Triclinic, P1	D_x = 2.866 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.0935 (15) Å	Cell parameters from 3316 reflections
b = 7.4606 (15) Å	θ = 3.7–25.5°
c = 8.0230 (15) Å	µ = 5.17 mm⁻¹
α = 83.776 (16)°	T = 173 K
β = 68.558 (15)°	Plate, colourless
γ = 87.850 (17)°	0.19 × 0.15 × 0.08 mm
V = 392.87 (14) Å³

Data collection top

Stoe IPDSII two-circle diffractometer	1420 independent reflections
Radiation source: fine-focus sealed tube	1245 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.082
ω scans	θ_max = 25.3°, θ_min = 3.7°
Absorption correction: multi-scan (MULABS; Spek, 2003; Blessing, 1995)	h = −8→8
T_min = 0.440, T_max = 0.683	k = −8→8
3316 measured reflections	l = −9→9

Refinement top

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)] = 0.048	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.125	w = 1/[σ²(F_o²) + (0.084P)²] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max < 0.001
1420 reflections	Δρ_max = 2.00 e Å⁻³
115 parameters	Δρ_min = −2.73 e Å⁻³
3 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: 0.011 (3)

Crystal data top

Cs₂Mg(H₂P₂O₇)₂·2H₂O	γ = 87.850 (17)°
M_r = 678.07	V = 392.87 (14) Å³
Triclinic, P1	Z = 1
a = 7.0935 (15) Å	Mo Kα radiation
b = 7.4606 (15) Å	µ = 5.17 mm⁻¹
c = 8.0230 (15) Å	T = 173 K
α = 83.776 (16)°	0.19 × 0.15 × 0.08 mm
β = 68.558 (15)°

Data collection top

Stoe IPDSII two-circle diffractometer	1420 independent reflections
Absorption correction: multi-scan (MULABS; Spek, 2003; Blessing, 1995)	1245 reflections with I > 2σ(I)
T_min = 0.440, T_max = 0.683	R_int = 0.082
3316 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	3 restraints
wR(F²) = 0.125	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	Δρ_max = 2.00 e Å⁻³
1420 reflections	Δρ_min = −2.73 e Å⁻³
115 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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

	x	y	z	U_iso*/U_eq
Cs1	0.09044 (7)	0.70386 (7)	0.27841 (6)	0.0186 (3)
Mg1	0.5000	0.5000	0.5000	0.0137 (8)
O1W	0.4211 (9)	0.2941 (8)	0.7146 (7)	0.0195 (14)
H1WA	0.413 (14)	0.319 (13)	0.817 (6)	0.023*
H1WB	0.355 (13)	0.201 (8)	0.719 (12)	0.023*
P1	0.3736 (3)	0.2528 (3)	0.2388 (3)	0.0129 (5)
P2	0.7759 (3)	0.1985 (3)	0.2518 (3)	0.0130 (5)
O1	0.3041 (8)	0.3164 (9)	0.0855 (8)	0.0190 (13)
O2	0.3344 (8)	0.3767 (8)	0.3829 (7)	0.0151 (12)
O3	0.2791 (9)	0.0628 (8)	0.3238 (8)	0.0181 (13)
H3	0.2828	0.0417	0.4276	0.022*
O4	0.6144 (8)	0.2214 (8)	0.1485 (7)	0.0162 (12)
O5	0.7572 (8)	0.3505 (8)	0.3636 (7)	0.0155 (12)
O6	0.7434 (9)	0.0105 (8)	0.3514 (8)	0.0216 (14)
O7	0.9737 (9)	0.2074 (9)	0.0826 (8)	0.0201 (14)
H7	1.0655	0.2565	0.1046	0.024*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cs1	0.0193 (4)	0.0231 (4)	0.0164 (4)	0.0023 (2)	−0.0101 (2)	−0.0027 (2)
Mg1	0.0124 (18)	0.018 (2)	0.0124 (18)	0.0022 (15)	−0.0069 (15)	−0.0011 (15)
O1W	0.030 (4)	0.022 (3)	0.010 (3)	−0.003 (3)	−0.012 (3)	−0.002 (2)
P1	0.0121 (10)	0.0171 (11)	0.0121 (10)	0.0017 (8)	−0.0073 (8)	−0.0031 (8)
P2	0.0131 (10)	0.0190 (11)	0.0104 (9)	0.0015 (8)	−0.0080 (8)	−0.0035 (8)
O1	0.016 (3)	0.029 (3)	0.017 (3)	−0.001 (2)	−0.012 (2)	−0.002 (3)
O2	0.013 (3)	0.021 (3)	0.017 (3)	0.000 (2)	−0.012 (2)	−0.006 (2)
O3	0.022 (3)	0.017 (3)	0.021 (3)	−0.005 (2)	−0.012 (3)	−0.005 (2)
O4	0.013 (3)	0.027 (3)	0.014 (3)	0.003 (2)	−0.011 (2)	−0.005 (2)
O5	0.014 (3)	0.025 (3)	0.012 (3)	0.002 (2)	−0.008 (2)	−0.009 (2)
O6	0.027 (3)	0.022 (3)	0.017 (3)	−0.002 (3)	−0.010 (3)	−0.001 (2)
O7	0.012 (3)	0.037 (4)	0.014 (3)	−0.001 (3)	−0.006 (2)	−0.008 (3)

Geometric parameters (Å, º) top

Cs1—O7ⁱ	3.092 (6)	O1W—Cs1^iv	3.608 (6)
Cs1—O3ⁱⁱ	3.151 (6)	O1W—H1WA	0.839 (10)
Cs1—O2	3.155 (6)	O1W—H1WB	0.839 (10)
Cs1—O6ⁱⁱⁱ	3.233 (7)	P1—O2	1.498 (6)
Cs1—O2^iv	3.259 (6)	P1—O1	1.510 (6)
Cs1—O4ⁱ	3.295 (5)	P1—O3	1.566 (6)
Cs1—O5^v	3.401 (5)	P1—O4	1.612 (6)
Cs1—O5^vi	3.450 (6)	P1—Cs1^iv	4.100 (2)
Cs1—O1	3.461 (6)	P2—O5	1.493 (6)
Cs1—O1W^v	3.486 (6)	P2—O6	1.518 (6)
Cs1—O1W^iv	3.608 (6)	P2—O7	1.553 (6)
Cs1—P1	3.836 (2)	P2—O4	1.637 (5)
Mg1—O2	2.046 (5)	P2—Cs1ⁱ	3.995 (2)
Mg1—O2^v	2.046 (5)	O2—Cs1^iv	3.259 (6)
Mg1—O5^v	2.103 (6)	O3—Cs1^viii	3.151 (6)
Mg1—O5	2.103 (6)	O3—H3	0.8400
Mg1—O1W^v	2.103 (5)	O4—Cs1ⁱ	3.295 (5)
Mg1—O1W	2.103 (5)	O5—Cs1^v	3.401 (5)
Mg1—Cs1^v	4.0953 (9)	O5—Cs1^vii	3.450 (6)
Mg1—Cs1^vii	4.1789 (11)	O6—Cs1^ix	3.233 (6)
Mg1—Cs1^iv	4.1790 (11)	O7—Cs1ⁱ	3.092 (6)
O1W—Cs1^v	3.486 (6)	O7—H7	0.8400

O7ⁱ—Cs1—O3ⁱⁱ	103.03 (16)	O5—Mg1—Cs1^v	56.01 (15)
O7ⁱ—Cs1—O2	127.15 (16)	O1W^v—Mg1—Cs1^v	121.65 (16)
O3ⁱⁱ—Cs1—O2	108.02 (15)	O1W—Mg1—Cs1^v	58.35 (16)
O7ⁱ—Cs1—O6ⁱⁱⁱ	74.51 (15)	O2—Mg1—Cs1	48.97 (16)
O3ⁱⁱ—Cs1—O6ⁱⁱⁱ	72.09 (16)	O2^v—Mg1—Cs1	131.03 (16)
O2—Cs1—O6ⁱⁱⁱ	155.89 (14)	O5^v—Mg1—Cs1	56.01 (15)
O7ⁱ—Cs1—O2^iv	112.39 (14)	O5—Mg1—Cs1	123.99 (15)
O3ⁱⁱ—Cs1—O2^iv	108.69 (15)	O1W^v—Mg1—Cs1	58.35 (16)
O2—Cs1—O2^iv	96.77 (14)	O1W—Mg1—Cs1	121.65 (16)
O6ⁱⁱⁱ—Cs1—O2^iv	61.80 (15)	Cs1^v—Mg1—Cs1	180.000 (7)
O7ⁱ—Cs1—O4ⁱ	44.14 (14)	O2—Mg1—Cs1^vii	130.16 (15)
O3ⁱⁱ—Cs1—O4ⁱ	84.93 (15)	O2^v—Mg1—Cs1^vii	49.84 (16)
O2—Cs1—O4ⁱ	97.36 (14)	O5^v—Mg1—Cs1^vii	124.62 (16)
O6ⁱⁱⁱ—Cs1—O4ⁱ	106.59 (14)	O5—Mg1—Cs1^vii	55.38 (16)
O2^iv—Cs1—O4ⁱ	156.16 (13)	O1W^v—Mg1—Cs1^vii	59.70 (16)
O7ⁱ—Cs1—O5^v	169.36 (14)	O1W—Mg1—Cs1^vii	120.30 (16)
O3ⁱⁱ—Cs1—O5^v	68.88 (15)	Cs1^v—Mg1—Cs1^vii	61.976 (19)
O2—Cs1—O5^v	52.76 (15)	Cs1—Mg1—Cs1^vii	118.02 (2)
O6ⁱⁱⁱ—Cs1—O5^v	108.24 (14)	O2—Mg1—Cs1^iv	49.84 (16)
O2^iv—Cs1—O5^v	77.41 (13)	O2^v—Mg1—Cs1^iv	130.16 (16)
O4ⁱ—Cs1—O5^v	126.34 (13)	O5^v—Mg1—Cs1^iv	55.38 (16)
O7ⁱ—Cs1—O5^vi	86.75 (14)	O5—Mg1—Cs1^iv	124.62 (16)
O3ⁱⁱ—Cs1—O5^vi	160.22 (15)	O1W^v—Mg1—Cs1^iv	120.30 (16)
O2—Cs1—O5^vi	78.07 (14)	O1W—Mg1—Cs1^iv	59.70 (16)
O6ⁱⁱⁱ—Cs1—O5^vi	94.58 (15)	Cs1^v—Mg1—Cs1^iv	118.024 (19)
O2^iv—Cs1—O5^vi	51.54 (14)	Cs1—Mg1—Cs1^iv	61.98 (2)
O4ⁱ—Cs1—O5^vi	113.40 (13)	Cs1^vii—Mg1—Cs1^iv	180.0
O5^v—Cs1—O5^vi	103.09 (12)	Mg1—O1W—Cs1^v	90.75 (19)
O7ⁱ—Cs1—O1	82.39 (15)	Mg1—O1W—Cs1^iv	90.08 (18)
O3ⁱⁱ—Cs1—O1	132.65 (15)	Cs1^v—O1W—Cs1^iv	178.20 (18)
O2—Cs1—O1	45.25 (13)	Mg1—O1W—H1WA	119 (7)
O6ⁱⁱⁱ—Cs1—O1	150.16 (14)	Cs1^v—O1W—H1WA	72 (7)
O2^iv—Cs1—O1	112.32 (15)	Cs1^iv—O1W—H1WA	106 (7)
O4ⁱ—Cs1—O1	66.40 (15)	Mg1—O1W—H1WB	124 (6)
O5^v—Cs1—O1	97.95 (14)	Cs1^v—O1W—H1WB	125 (7)
O5^vi—Cs1—O1	65.07 (13)	Cs1^iv—O1W—H1WB	55 (7)
O7ⁱ—Cs1—O1W^v	119.58 (14)	H1WA—O1W—H1WB	113 (8)
O3ⁱⁱ—Cs1—O1W^v	59.65 (15)	O2—P1—O1	116.7 (4)
O2—Cs1—O1W^v	51.99 (14)	O2—P1—O3	110.1 (3)
O6ⁱⁱⁱ—Cs1—O1W^v	131.44 (15)	O1—P1—O3	108.9 (3)
O2^iv—Cs1—O1W^v	128.02 (13)	O2—P1—O4	108.7 (3)
O4ⁱ—Cs1—O1W^v	75.64 (13)	O1—P1—O4	106.0 (3)
O5^v—Cs1—O1W^v	50.71 (13)	O3—P1—O4	106.0 (3)
O5^vi—Cs1—O1W^v	130.02 (14)	O2—P1—Cs1	52.5 (2)
O1—Cs1—O1W^v	76.60 (14)	O1—P1—Cs1	64.3 (3)
O7ⁱ—Cs1—O1W^iv	61.98 (13)	O3—P1—Cs1	126.4 (2)
O3ⁱⁱ—Cs1—O1W^iv	119.49 (15)	O4—P1—Cs1	127.4 (2)
O2—Cs1—O1W^iv	128.11 (13)	O2—P1—Cs1^iv	46.6 (2)
O6ⁱⁱⁱ—Cs1—O1W^iv	47.53 (15)	O1—P1—Cs1^iv	110.0 (2)
O2^iv—Cs1—O1W^iv	50.41 (12)	O3—P1—Cs1^iv	69.8 (2)
O4ⁱ—Cs1—O1W^iv	105.98 (12)	O4—P1—Cs1^iv	143.1 (2)
O5^v—Cs1—O1W^iv	127.65 (13)	Cs1—P1—Cs1^iv	64.84 (4)
O5^vi—Cs1—O1W^iv	50.22 (14)	O5—P2—O6	116.1 (3)
O1—Cs1—O1W^iv	104.72 (14)	O5—P2—O7	112.9 (3)
O1W^v—Cs1—O1W^iv	178.20 (18)	O6—P2—O7	110.9 (4)
O7ⁱ—Cs1—P1	105.41 (12)	O5—P2—O4	110.8 (3)
O3ⁱⁱ—Cs1—P1	122.63 (12)	O6—P2—O4	106.4 (3)
O2—Cs1—P1	22.12 (11)	O7—P2—O4	98.0 (3)
O6ⁱⁱⁱ—Cs1—P1	164.02 (12)	O5—P2—Cs1ⁱ	120.3 (2)
O2^iv—Cs1—P1	104.76 (11)	O6—P2—Cs1ⁱ	123.5 (3)
O4ⁱ—Cs1—P1	82.42 (11)	O4—P2—Cs1ⁱ	53.5 (2)
O5^v—Cs1—P1	74.87 (11)	P1—O1—Cs1	92.5 (3)
O5^vi—Cs1—P1	69.55 (10)	P1—O2—Mg1	137.3 (4)
O1—Cs1—P1	23.15 (9)	P1—O2—Cs1	105.4 (3)
O1W^v—Cs1—P1	63.00 (11)	Mg1—O2—Cs1	101.8 (2)
O1W^iv—Cs1—P1	117.80 (10)	P1—O2—Cs1^iv	113.8 (3)
O2—Mg1—O2^v	179.999 (1)	Mg1—O2—Cs1^iv	101.5 (2)
O2—Mg1—O5^v	89.5 (2)	Cs1—O2—Cs1^iv	83.23 (14)
O2^v—Mg1—O5^v	90.5 (2)	P1—O3—Cs1^viii	148.3 (3)
O2—Mg1—O5	90.5 (2)	P1—O3—H3	109.5
O2^v—Mg1—O5	89.5 (2)	Cs1^viii—O3—H3	102.2
O5^v—Mg1—O5	179.999 (1)	P1—O4—P2	126.8 (4)
O2—Mg1—O1W^v	89.7 (2)	P1—O4—Cs1ⁱ	128.3 (3)
O2^v—Mg1—O1W^v	90.3 (2)	P2—O4—Cs1ⁱ	103.0 (2)
O5^v—Mg1—O1W^v	89.1 (2)	P2—O5—Mg1	129.5 (3)
O5—Mg1—O1W^v	90.9 (2)	P2—O5—Cs1^v	120.1 (3)
O2—Mg1—O1W	90.3 (2)	Mg1—O5—Cs1^v	93.14 (17)
O2^v—Mg1—O1W	89.7 (2)	P2—O5—Cs1^vii	127.4 (3)
O5^v—Mg1—O1W	90.9 (2)	Mg1—O5—Cs1^vii	94.5 (2)
O5—Mg1—O1W	89.1 (2)	Cs1^v—O5—Cs1^vii	76.91 (12)
O1W^v—Mg1—O1W	180.0 (3)	P2—O6—Cs1^ix	123.7 (3)
O2—Mg1—Cs1^v	131.03 (16)	P2—O7—Cs1ⁱ	114.5 (3)
O2^v—Mg1—Cs1^v	48.97 (16)	P2—O7—H7	109.5
O5^v—Mg1—Cs1^v	123.99 (15)	Cs1ⁱ—O7—H7	122.0

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x, y+1, z; (iii) x−1, y+1, z; (iv) −x, −y+1, −z+1; (v) −x+1, −y+1, −z+1; (vi) x−1, y, z; (vii) x+1, y, z; (viii) x, y−1, z; (ix) x+1, y−1, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1^x	0.84 (1)	2.01 (4)	2.804 (8)	158 (9)
O1W—H1WB···O6^xi	0.84 (1)	1.97 (3)	2.778 (9)	162 (9)
O3—H3···O6^xi	0.84	1.72	2.551 (8)	172
O7—H7···O1^vii	0.84	1.71	2.518 (8)	159

Symmetry codes: (vii) x+1, y, z; (x) x, y, z+1; (xi) −x+1, −y, −z+1.

Experimental details

Crystal data
Chemical formula	Cs₂Mg(H₂P₂O₇)₂·2H₂O
M_r	678.07
Crystal system, space group	Triclinic, P1
Temperature (K)	173
a, b, c (Å)	7.0935 (15), 7.4606 (15), 8.0230 (15)
α, β, γ (°)	83.776 (16), 68.558 (15), 87.850 (17)
V (Å³)	392.87 (14)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	5.17
Crystal size (mm)	0.19 × 0.15 × 0.08

Data collection
Diffractometer	Stoe IPDSII two-circle diffractometer
Absorption correction	Multi-scan (MULABS; Spek, 2003; Blessing, 1995)
T_min, T_max	0.440, 0.683
No. of measured, independent and observed [I > 2σ(I)] reflections	3316, 1420, 1245
R_int	0.082
(sin θ/λ)_max (Å⁻¹)	0.602

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.125, 1.02
No. of reflections	1420
No. of parameters	115
No. of restraints	3
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	2.00, −2.73

Computer programs: X-AREA (Stoe & Cie, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL-Plus (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1ⁱ	0.839 (10)	2.01 (4)	2.804 (8)	158 (9)
O1W—H1WB···O6ⁱⁱ	0.839 (10)	1.97 (3)	2.778 (9)	162 (9)
O3—H3···O6ⁱⁱ	0.84	1.72	2.551 (8)	172.2
O7—H7···O1ⁱⁱⁱ	0.84	1.71	2.518 (8)	159.4

Symmetry codes: (i) x, y, z+1; (ii) −x+1, −y, −z+1; (iii) x+1, y, z.

References

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Volume 65| Part 1| January 2009| Page i3

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