Dicaesium magnesium bis­(dihydrogen phosphate(V)) dihydrate

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.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](P-O) = 0.006 Å
• R factor = 0.048
• wR factor = 0.125
• Data-to-parameter ratio = 12.3

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT731_ALERT_1_B Bond    Calc     0.84(6), Rep   0.839(10) ......       6.00 su-Ra
              O1W  -H1WA    1.555   1.555
PLAT731_ALERT_1_B Bond    Calc     0.84(7), Rep   0.839(10) ......       7.00 su-Ra
              O1W  -H1WB    1.555   1.555
PLAT735_ALERT_1_B D-H     Calc     0.84(6), Rep   0.839(10) ......       6.00 su-Ra
              O1W  -H1#     1.555   1.555
PLAT735_ALERT_1_B D-H     Calc     0.84(7), Rep   0.839(10) ......       7.00 su-Ra
              O1W  -H2#     1.555   1.555

Alert level C
            Value of measurement temperature given =   173.000
            Value of melting point given =     0.000
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.79
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.97
PLAT153_ALERT_1_C The su's on the Cell Axes   are Equal (x 100000)        150 Ang.
PLAT736_ALERT_1_C H...A   Calc     1.97(8), Rep     1.97(3) ......       2.67 su-Ra
              H2#  -O6      1.555   2.656

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          2

   0 ALERT level A = In general: serious problem
   4 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   7 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

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

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); .

S2. Experimental

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.

S3. Refinement

All H atoms were located in a difference map. The water H atoms were refined with the O-H bonds restrained to 0.84 (1)Å and the H···H distances restrained to 1.4 (1)Å and with fixed individual displacement parameters [U(H) = 1.2 U_eq(O)]. The H atoms of the hydroxyl groups bonded to P were refined using a riding model with O-H = 0.84Å, U(H) = 1.2 U_eq(O) and P-O-H = 109.5 °.

Computing details

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

	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

Crystal data

Cs2Mg(H2P2O7)2·2H2O	Z = 1
Mr = 678.07	F(000) = 318
Triclinic, P1	Dx = 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) Å^3

Data collection

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

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.048	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.125	w = 1/[σ^2(Fo^2) + (0.084P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
1420 reflections	Δρmax = 2.00 e Å^−3
115 parameters	Δρmin = −2.73 e Å^−3
3 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.011 (3)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
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 (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
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)

Cs1—O7^i	3.092 (6)	O1W—Cs1^iv	3.608 (6)
Cs1—O3^ii	3.151 (6)	O1W—H1WA	0.839 (10)
Cs1—O2	3.155 (6)	O1W—H1WB	0.839 (10)
Cs1—O6^iii	3.233 (7)	P1—O2	1.498 (6)
Cs1—O2^iv	3.259 (6)	P1—O1	1.510 (6)
Cs1—O4^i	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—Cs1^i	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—Cs1^i	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—Cs1^i	3.092 (6)
O1W—Cs1^v	3.486 (6)	O7—H7	0.8400
O7^i—Cs1—O3^ii	103.03 (16)	O5—Mg1—Cs1^v	56.01 (15)
O7^i—Cs1—O2	127.15 (16)	O1W^v—Mg1—Cs1^v	121.65 (16)
O3^ii—Cs1—O2	108.02 (15)	O1W—Mg1—Cs1^v	58.35 (16)
O7^i—Cs1—O6^iii	74.51 (15)	O2—Mg1—Cs1	48.97 (16)
O3^ii—Cs1—O6^iii	72.09 (16)	O2^v—Mg1—Cs1	131.03 (16)
O2—Cs1—O6^iii	155.89 (14)	O5^v—Mg1—Cs1	56.01 (15)
O7^i—Cs1—O2^iv	112.39 (14)	O5—Mg1—Cs1	123.99 (15)
O3^ii—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)
O6^iii—Cs1—O2^iv	61.80 (15)	Cs1^v—Mg1—Cs1	180.000 (7)
O7^i—Cs1—O4^i	44.14 (14)	O2—Mg1—Cs1^vii	130.16 (15)
O3^ii—Cs1—O4^i	84.93 (15)	O2^v—Mg1—Cs1^vii	49.84 (16)
O2—Cs1—O4^i	97.36 (14)	O5^v—Mg1—Cs1^vii	124.62 (16)
O6^iii—Cs1—O4^i	106.59 (14)	O5—Mg1—Cs1^vii	55.38 (16)
O2^iv—Cs1—O4^i	156.16 (13)	O1W^v—Mg1—Cs1^vii	59.70 (16)
O7^i—Cs1—O5^v	169.36 (14)	O1W—Mg1—Cs1^vii	120.30 (16)
O3^ii—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)
O6^iii—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)
O4^i—Cs1—O5^v	126.34 (13)	O5^v—Mg1—Cs1^iv	55.38 (16)
O7^i—Cs1—O5^vi	86.75 (14)	O5—Mg1—Cs1^iv	124.62 (16)
O3^ii—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)
O6^iii—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)
O4^i—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)
O7^i—Cs1—O1	82.39 (15)	Mg1—O1W—Cs1^iv	90.08 (18)
O3^ii—Cs1—O1	132.65 (15)	Cs1^v—O1W—Cs1^iv	178.20 (18)
O2—Cs1—O1	45.25 (13)	Mg1—O1W—H1WA	119 (7)
O6^iii—Cs1—O1	150.16 (14)	Cs1^v—O1W—H1WA	72 (7)
O2^iv—Cs1—O1	112.32 (15)	Cs1^iv—O1W—H1WA	106 (7)
O4^i—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)
O7^i—Cs1—O1W^v	119.58 (14)	H1WA—O1W—H1WB	113 (8)
O3^ii—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)
O6^iii—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)
O4^i—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)
O7^i—Cs1—O1W^iv	61.98 (13)	O3—P1—Cs1	126.4 (2)
O3^ii—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)
O6^iii—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)
O4^i—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)
O7^i—Cs1—P1	105.41 (12)	O5—P2—O4	110.8 (3)
O3^ii—Cs1—P1	122.63 (12)	O6—P2—O4	106.4 (3)
O2—Cs1—P1	22.12 (11)	O7—P2—O4	98.0 (3)
O6^iii—Cs1—P1	164.02 (12)	O5—P2—Cs1^i	120.3 (2)
O2^iv—Cs1—P1	104.76 (11)	O6—P2—Cs1^i	123.5 (3)
O4^i—Cs1—P1	82.42 (11)	O4—P2—Cs1^i	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—Cs1^i	128.3 (3)
O2^v—Mg1—O1W^v	90.3 (2)	P2—O4—Cs1^i	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—Cs1^i	114.5 (3)
O2^v—Mg1—Cs1^v	48.97 (16)	P2—O7—H7	109.5
O5^v—Mg1—Cs1^v	123.99 (15)	Cs1^i—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)

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.