Tetra­kis(3,5-xylidinium) dihydrogen cyclo­hexa­phosphate dihydrate

Marouani, H.; Rzaigui, M.

doi:10.1107/S1600536809054452

Tetrakis(3,5-xylidinium) dihydrogen cyclohexaphosphate dihydrate

In the title compound, 4C₈H₁₂N⁺·H₂P₆O₁₈⁴⁻·2H₂O, the complete cyclohexaphosphate anion is generated by inversion symmetry. Crystal cohesion and stability are supported by electrostatic interactions which, together with N—H

O and O—H

O hydrogen bonds, build up a three-dimensional network.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536809054452/hb5267sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536809054452/hb5267Isup2.hkl Contains datablock I

CCDC reference: 766879

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Key indicators

Single-crystal X-ray study
T = 293 K
Mean (C-C) = 0.003 Å
R factor = 0.052
wR factor = 0.141
Data-to-parameter ratio = 33.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O4
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O7
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         P2
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          5
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         30

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K
PLAT793_ALERT_4_G The Model has Chirality at P3      (Verify) ....          S

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

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 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

Comment top

Following investigations of Schülke and Kayser (Schulke, et al., 1985)on the condensation-cyclization on LiH₂PO₄ into Li₆P₆O₁₈, the crystal chemistry of cyclohexaphosphates developed rapidly. In the present investigation we report synthesis and crystal structure of a first cyclohexaphosphate acid, [3,5-(CH₃)₂C₆H₃NH₃]₄H₂P₆O₁₈.2H₂O, (I).

The title compound, is built up from H₂P₆O₁₈^4- anion, four organic 3,5-xylidiniuium cations and two water molecules (Fig. 1). A half of the anion, two organic cations and a water molecule constitute the asymmetric unit of (I).

The atomic arrangement is a typical organization in layers as shows the figure 2. These corrugated layers are constituted of anions and water molecules that develop in the same way to plans (b,c) in x = 0. Charge compensation of these layers is achieved by the incorporation of the protonated 3,5-xylidinium cation in the interlayer spaces establishing H-bonds via their NH₃ groups with H₂P₆O₁₈ rings and water molecules. Inside such a structure, the phosphoric ring has an -1 internal symmetry. It develops around the inversion centers (0,0,0) and (0,1/2,1/2), so it is built up by only three independent tetrahedra. Among the P—O distances in PO₄ tetrahedra, we can distinguish three different types. The longest ones correspond to the bridging oxygen atom, the intermediate one, corresponds to the P—OH bonding and the shortest, correspond to the external oxygen atoms. The calculated average values of the distortion indices (Baur, 1974) corresponding to the different angles and distances in the PO₄ tetrahedra [DI (OPO) = 0.040; DI (PO) = 0.037; and DI (OO) = 0.016], show a pronounced distortion of the PO distances and OPO angles if compared to OO distances. So, the phosphate group can be considered as a rigid regular arrangement of oxygen atoms, with the phosphorus atom displaced from the gravity centre. It is worth noting that the strong H-bond between phosphoric rings (Table 1)(dO···O = 2.421 (2) Å < 2.73 Å) is never observed in cyclohexaphosphates.

With regards to the organic cation arrangement, these groups are in opposition, by creating thus a local invesion center. Interatomic bond lengths and angles of these groups spread within the respective ranges of 1.371 (3)–1.466 (2) Å and 118.2 (2)–122.1 (2)°. These values are similar to those obtained with the same isomers [Khederi, et al., 2001, Rayes, et al., 2004, Amri, et al., 2008] The aromatic ring of the protonated used amine display an almost coplanar configuration with mean plane deviation of 0.000085 Å and 0.000245 Å. The interplanar distance between the aryl rings of the organic cations is in the vicinity of 4.00 Å, which is significantly longer than 3.80 Å for the π-π interaction (Janiak, 2000). The cohesion forces in this compound are assured by electrostatic interactions, van der Waals contacts and hydrogen bonds (O—H···O, N—H···O).

Related literature top

For related structures, see: Khederi et al. (2001); Rayes et al. (2004); Amri et al. (2008); Janiak et al. (2000). For a discussion on hydrogen bonding, see: Brown (1976). For tetrahedral distortions, see: Baur (1974). For the preparation of cyclohexaphosphoric acid, see: Schulke & Kayser (1985).

Experimental top

The title compound, [3,5-(CH₃)₂C₆H₃NH₃]₄H₂P₆O₁₈.2H₂O was synthesized by reaction of the cyclohexaphosphoric acid on 3,5-xylidine in an aqueous solution. The used acid was produced from a Li₆P₆O₁₈ (Schulke et al., 1985) solution by cation exchange on resins (Amberlite IR 120). The obtained H₆P₆O₁₈ was added until the a pH between 1 and 2 in the final solution resulted. The same method of preparation was used for the synthesis of [3,5-(CH₃)₂C₆H₃NH₃]₆P₆O₁₈.6H₂O, but in a less acidic medium (Khederi, et al., 2001). Then this solution was slowly evaporated at room temperature for several days until the formation of transparent prisms of (I) were obtained.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. A view of (I) with displacement ellipsoids drawn at the 30% probability level. Symmetry code: (i) - x, - y, - z.
	Fig. 2. Projection of (I) along the c axis.

Tetrakis(3,5-xylidinium) dihydrogen cyclohexaphosphate dihydrate top

Crystal data top

4C₈H₁₂N⁺·H₂P₆O₁₈⁴⁻·2H₂O	F(000) = 1048
M_r = 1000.61	D_x = 1.477 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 17.254 (3) Å	θ = 6.3–10.1°
b = 11.763 (5) Å	µ = 0.32 mm⁻¹
c = 11.556 (2) Å	T = 293 K
β = 106.41 (3)°	Prism, colourless
V = 2249.9 (11) Å³	0.35 × 0.20 × 0.01 mm
Z = 2

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.039
Radiation source: Enraf Nonius FR590	θ_max = 35.0°, θ_min = 3.0°
Graphite monochromator	h = 0→27
non–profiled ω scans	k = −18→0
10097 measured reflections	l = −18→17
9844 independent reflections	2 standard reflections every 120 min
5567 reflections with I > 2σ(I)	intensity decay: 11%

Refinement top

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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.141	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ²(F_o²) + (0.0664P)² + 0.0078P] where P = (F_o² + 2F_c²)/3
9844 reflections	(Δ/σ)_max = 0.001
295 parameters	Δρ_max = 0.50 e Å⁻³
3 restraints	Δρ_min = −0.51 e Å⁻³

Crystal data top

4C₈H₁₂N⁺·H₂P₆O₁₈⁴⁻·2H₂O	V = 2249.9 (11) Å³
M_r = 1000.61	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 17.254 (3) Å	µ = 0.32 mm⁻¹
b = 11.763 (5) Å	T = 293 K
c = 11.556 (2) Å	0.35 × 0.20 × 0.01 mm
β = 106.41 (3)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.039
10097 measured reflections	2 standard reflections every 120 min
9844 independent reflections	intensity decay: 11%
5567 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.052	3 restraints
wR(F²) = 0.141	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	Δρ_max = 0.50 e Å⁻³
9844 reflections	Δρ_min = −0.51 e Å⁻³
295 parameters

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
P1	0.00136 (3)	0.52037 (4)	0.73695 (4)	0.02425 (10)
P2	0.09276 (3)	0.68827 (4)	0.63729 (4)	0.02327 (10)
P3	0.13602 (3)	0.55149 (4)	0.45087 (4)	0.02452 (10)
O1	−0.04452 (9)	0.43770 (12)	0.62693 (12)	0.0358 (3)
O2	−0.05542 (9)	0.55967 (13)	0.80125 (13)	0.0383 (3)
O3	0.07729 (8)	0.46237 (12)	0.80005 (12)	0.0331 (3)
O4	0.01792 (9)	0.62742 (15)	0.66154 (17)	0.0516 (5)
O5	0.06005 (9)	0.77774 (12)	0.54796 (13)	0.0355 (3)
O6	0.15290 (10)	0.71634 (14)	0.75342 (13)	0.0463 (4)
O7	0.13336 (10)	0.58897 (13)	0.58091 (12)	0.0411 (4)
O8	0.18549 (10)	0.63572 (15)	0.40517 (15)	0.0470 (4)
H8	0.1563	0.6703	0.3476	0.071*
O9	0.16580 (8)	0.43352 (11)	0.46188 (12)	0.0299 (3)
O1W	0.10923 (9)	0.23683 (13)	0.55367 (13)	0.0350 (3)
H2W	0.1207 (13)	0.3026 (12)	0.534 (2)	0.049 (8)*
H1W	0.0587 (6)	0.226 (2)	0.535 (2)	0.051 (8)*
N1	0.15651 (10)	0.26040 (14)	0.80220 (14)	0.0286 (3)
H1A	0.1545	0.1974	0.8438	0.043*
H1B	0.1444	0.2439	0.7240	0.043*
H1C	0.1211	0.3107	0.8146	0.043*
N2	0.13845 (10)	0.97750 (14)	0.54343 (15)	0.0330 (3)
H2A	0.1291	1.0056	0.4692	0.050*
H2B	0.1225	1.0275	0.5899	0.050*
H2C	0.1111	0.9129	0.5408	0.050*
C1	0.23806 (11)	0.30866 (16)	0.84216 (16)	0.0277 (3)
C2	0.26029 (13)	0.38692 (18)	0.76896 (19)	0.0374 (5)
H2	0.2242	0.4077	0.6958	0.045*
C3	0.33672 (15)	0.4345 (2)	0.8052 (2)	0.0442 (5)
C4	0.38869 (14)	0.4024 (2)	0.9153 (2)	0.0448 (5)
H4	0.4401	0.4342	0.9397	0.054*
C5	0.36648 (13)	0.3244 (2)	0.9902 (2)	0.0389 (5)
C6	0.28937 (12)	0.27755 (18)	0.95214 (18)	0.0338 (4)
H6	0.2726	0.2255	1.0007	0.041*
C7	0.3613 (2)	0.5219 (3)	0.7259 (3)	0.0738 (10)
H7A	0.3367	0.5936	0.7336	0.111*
H7B	0.3438	0.4974	0.6434	0.111*
H7C	0.4190	0.5301	0.7505	0.111*
C8	0.42344 (16)	0.2895 (3)	1.1093 (2)	0.0611 (8)
H8A	0.4552	0.2259	1.0973	0.092*
H8B	0.3930	0.2683	1.1638	0.092*
H8C	0.4584	0.3519	1.1428	0.092*
C9	0.22502 (12)	0.95537 (16)	0.59349 (17)	0.0301 (4)
C10	0.26548 (14)	0.99879 (18)	0.70482 (18)	0.0376 (5)
H10	0.2387	1.0454	0.7460	0.045*
C11	0.34615 (15)	0.9726 (2)	0.7550 (2)	0.0457 (5)
C12	0.38358 (15)	0.9013 (2)	0.6916 (2)	0.0508 (6)
H12	0.4376	0.8823	0.7253	0.061*
C13	0.34264 (15)	0.8571 (2)	0.5790 (2)	0.0454 (5)
C14	0.26241 (14)	0.88654 (19)	0.5298 (2)	0.0391 (5)
H14	0.2340	0.8598	0.4540	0.047*
C15	0.3918 (2)	1.0199 (3)	0.8766 (3)	0.0760 (10)
H15A	0.4073	1.0970	0.8674	0.114*
H15B	0.4392	0.9749	0.9101	0.114*
H15C	0.3579	1.0179	0.9296	0.114*
C16	0.3838 (2)	0.7769 (3)	0.5129 (3)	0.0766 (10)
H16A	0.3464	0.7193	0.4731	0.115*
H16B	0.4293	0.7419	0.5695	0.115*
H16C	0.4021	0.8186	0.4542	0.115*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P1	0.0263 (2)	0.0223 (2)	0.0234 (2)	0.00168 (17)	0.00594 (16)	0.00207 (16)
P2	0.0260 (2)	0.01997 (19)	0.02237 (19)	−0.00016 (16)	0.00439 (16)	−0.00186 (15)
P3	0.0315 (2)	0.0211 (2)	0.01944 (19)	0.00324 (17)	0.00459 (17)	−0.00015 (15)
O1	0.0347 (7)	0.0350 (7)	0.0313 (7)	0.0121 (6)	−0.0010 (6)	−0.0107 (6)
O2	0.0436 (8)	0.0418 (8)	0.0324 (7)	0.0089 (7)	0.0154 (6)	−0.0037 (6)
O3	0.0305 (7)	0.0324 (7)	0.0315 (7)	0.0082 (6)	0.0007 (5)	0.0033 (5)
O4	0.0324 (8)	0.0516 (10)	0.0708 (11)	0.0029 (7)	0.0147 (8)	0.0358 (9)
O5	0.0356 (7)	0.0252 (6)	0.0419 (8)	0.0001 (6)	0.0045 (6)	0.0094 (6)
O6	0.0525 (10)	0.0407 (9)	0.0335 (8)	0.0069 (7)	−0.0078 (7)	−0.0156 (6)
O7	0.0591 (10)	0.0392 (8)	0.0218 (6)	0.0212 (7)	0.0061 (6)	−0.0037 (6)
O8	0.0470 (9)	0.0448 (9)	0.0454 (9)	−0.0054 (8)	0.0066 (7)	0.0210 (7)
O9	0.0348 (7)	0.0230 (6)	0.0306 (6)	0.0049 (5)	0.0073 (5)	−0.0017 (5)
O1W	0.0338 (8)	0.0331 (8)	0.0359 (7)	−0.0025 (6)	0.0064 (6)	0.0061 (6)
N1	0.0291 (8)	0.0261 (7)	0.0294 (7)	−0.0014 (6)	0.0061 (6)	−0.0001 (6)
N2	0.0352 (9)	0.0279 (8)	0.0350 (8)	−0.0015 (7)	0.0085 (7)	0.0026 (7)
C1	0.0264 (8)	0.0258 (8)	0.0294 (8)	−0.0014 (7)	0.0055 (7)	−0.0015 (7)
C2	0.0392 (11)	0.0373 (11)	0.0323 (10)	−0.0051 (9)	0.0044 (8)	0.0045 (8)
C3	0.0442 (12)	0.0455 (13)	0.0428 (12)	−0.0135 (10)	0.0122 (10)	0.0040 (10)
C4	0.0312 (11)	0.0496 (13)	0.0508 (13)	−0.0097 (10)	0.0067 (10)	−0.0007 (11)
C5	0.0313 (10)	0.0422 (12)	0.0380 (11)	0.0008 (9)	0.0015 (8)	−0.0005 (9)
C6	0.0322 (10)	0.0350 (10)	0.0324 (9)	−0.0008 (8)	0.0059 (8)	0.0036 (8)
C7	0.071 (2)	0.080 (2)	0.0672 (19)	−0.0334 (17)	0.0143 (16)	0.0215 (16)
C8	0.0433 (14)	0.078 (2)	0.0486 (14)	−0.0039 (13)	−0.0086 (11)	0.0127 (13)
C9	0.0334 (9)	0.0254 (8)	0.0316 (9)	−0.0034 (7)	0.0091 (7)	0.0019 (7)
C10	0.0438 (12)	0.0372 (11)	0.0306 (9)	0.0016 (9)	0.0087 (9)	−0.0024 (8)
C11	0.0446 (12)	0.0513 (14)	0.0341 (11)	−0.0006 (11)	−0.0003 (9)	−0.0010 (10)
C12	0.0362 (12)	0.0537 (15)	0.0579 (15)	0.0039 (11)	0.0057 (11)	0.0023 (12)
C13	0.0438 (12)	0.0412 (12)	0.0558 (14)	−0.0026 (10)	0.0217 (11)	−0.0076 (11)
C14	0.0423 (12)	0.0380 (11)	0.0377 (10)	−0.0082 (9)	0.0124 (9)	−0.0095 (9)
C15	0.070 (2)	0.090 (2)	0.0484 (15)	0.0066 (18)	−0.0148 (14)	−0.0129 (16)
C16	0.0589 (18)	0.082 (2)	0.098 (3)	0.0113 (17)	0.0369 (18)	−0.028 (2)

Geometric parameters (Å, º) top

P1—O2	1.4619 (15)	C3—C7	1.515 (3)
P1—O3	1.4744 (14)	C4—C5	1.388 (3)
P1—O4	1.6024 (16)	C4—H4	0.9300
P1—O1	1.6187 (15)	C5—C6	1.392 (3)
P2—O5	1.4706 (15)	C5—C8	1.505 (3)
P2—O6	1.4832 (15)	C6—H6	0.9300
P2—O4	1.5692 (16)	C7—H7A	0.9600
P2—O7	1.5930 (15)	C7—H7B	0.9600
P3—O9	1.4728 (15)	C7—H7C	0.9600
P3—O8	1.4980 (16)	C8—H8A	0.9600
P3—O7	1.5790 (14)	C8—H8B	0.9600
P3—O1ⁱ	1.5859 (15)	C8—H8C	0.9600
O1—P3ⁱ	1.5859 (15)	C9—C14	1.371 (3)
O8—H8	0.8200	C9—C10	1.377 (3)
O1W—H2W	0.847 (9)	C10—C11	1.383 (3)
O1W—H1W	0.846 (9)	C10—H10	0.9300
N1—C1	1.466 (2)	C11—C12	1.387 (4)
N1—H1A	0.8900	C11—C15	1.510 (3)
N1—H1B	0.8900	C12—C13	1.393 (3)
N1—H1C	0.8900	C12—H12	0.9300
N2—C9	1.465 (3)	C13—C14	1.384 (3)
N2—H2A	0.8900	C13—C16	1.512 (4)
N2—H2B	0.8900	C14—H14	0.9300
N2—H2C	0.8900	C15—H15A	0.9600
C1—C2	1.376 (3)	C15—H15B	0.9600
C1—C6	1.377 (3)	C15—H15C	0.9600
C2—C3	1.384 (3)	C16—H16A	0.9600
C2—H2	0.9300	C16—H16B	0.9600
C3—C4	1.386 (3)	C16—H16C	0.9600

O2—P1—O3	121.63 (9)	C4—C5—C8	121.8 (2)
O2—P1—O4	106.02 (10)	C6—C5—C8	120.0 (2)
O3—P1—O4	111.25 (9)	C1—C6—C5	119.6 (2)
O2—P1—O1	109.87 (9)	C1—C6—H6	120.2
O3—P1—O1	106.24 (8)	C5—C6—H6	120.2
O4—P1—O1	99.66 (10)	C3—C7—H7A	109.5
O5—P2—O6	120.50 (10)	C3—C7—H7B	109.5
O5—P2—O4	106.25 (9)	H7A—C7—H7B	109.5
O6—P2—O4	109.92 (11)	C3—C7—H7C	109.5
O5—P2—O7	111.32 (9)	H7A—C7—H7C	109.5
O6—P2—O7	104.90 (9)	H7B—C7—H7C	109.5
O4—P2—O7	102.57 (10)	C5—C8—H8A	109.5
O9—P3—O8	115.72 (10)	C5—C8—H8B	109.5
O9—P3—O7	106.50 (8)	H8A—C8—H8B	109.5
O8—P3—O7	108.87 (10)	C5—C8—H8C	109.5
O9—P3—O1ⁱ	113.06 (8)	H8A—C8—H8C	109.5
O8—P3—O1ⁱ	108.80 (9)	H8B—C8—H8C	109.5
O7—P3—O1ⁱ	103.02 (9)	C14—C9—C10	121.9 (2)
P3ⁱ—O1—P1	125.79 (9)	C14—C9—N2	118.34 (18)
P2—O4—P1	137.54 (11)	C10—C9—N2	119.63 (18)
P3—O7—P2	136.74 (10)	C9—C10—C11	119.6 (2)
P3—O8—H8	109.5	C9—C10—H10	120.2
H2W—O1W—H1W	111.4 (19)	C11—C10—H10	120.2
C1—N1—H1A	109.5	C10—C11—C12	118.5 (2)
C1—N1—H1B	109.5	C10—C11—C15	120.4 (2)
H1A—N1—H1B	109.5	C12—C11—C15	121.1 (2)
C1—N1—H1C	109.5	C11—C12—C13	122.0 (2)
H1A—N1—H1C	109.5	C11—C12—H12	119.0
H1B—N1—H1C	109.5	C13—C12—H12	119.0
C9—N2—H2A	109.5	C14—C13—C12	118.4 (2)
C9—N2—H2B	109.5	C14—C13—C16	120.5 (2)
H2A—N2—H2B	109.5	C12—C13—C16	121.2 (2)
C9—N2—H2C	109.5	C9—C14—C13	119.6 (2)
H2A—N2—H2C	109.5	C9—C14—H14	120.2
H2B—N2—H2C	109.5	C13—C14—H14	120.2
C2—C1—C6	121.79 (18)	C11—C15—H15A	109.5
C2—C1—N1	118.35 (17)	C11—C15—H15B	109.5
C6—C1—N1	119.83 (17)	H15A—C15—H15B	109.5
C1—C2—C3	119.47 (19)	C11—C15—H15C	109.5
C1—C2—H2	120.3	H15A—C15—H15C	109.5
C3—C2—H2	120.3	H15B—C15—H15C	109.5
C2—C3—C4	118.8 (2)	C13—C16—H16A	109.5
C2—C3—C7	119.8 (2)	C13—C16—H16B	109.5
C4—C3—C7	121.4 (2)	H16A—C16—H16B	109.5
C3—C4—C5	122.1 (2)	C13—C16—H16C	109.5
C3—C4—H4	118.9	H16A—C16—H16C	109.5
C5—C4—H4	118.9	H16B—C16—H16C	109.5
C4—C5—C6	118.2 (2)

Symmetry code: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O8—H8···O6ⁱⁱ	0.82	1.71	2.421 (2)	144
O1W—H2W···O9	0.85 (1)	2.01 (1)	2.831 (2)	164 (2)
O1W—H1W···O5ⁱ	0.85 (1)	2.00 (1)	2.829 (2)	165 (2)
N1—H1A···O9ⁱⁱⁱ	0.89	2.03	2.910 (2)	170
N1—H1B···O1W	0.89	1.89	2.769 (2)	169
N1—H1C···O3	0.89	1.93	2.738 (2)	151
N2—H2A···O3ⁱⁱ	0.89	1.94	2.801 (2)	161
N2—H2B···O2^iv	0.89	1.97	2.768 (2)	148
N2—H2C···O5	0.89	1.83	2.719 (2)	175

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x, −y+3/2, z−1/2; (iii) x, −y+1/2, z+1/2; (iv) −x, y+1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	4C₈H₁₂N⁺·H₂P₆O₁₈⁴⁻·2H₂O
M_r	1000.61
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	17.254 (3), 11.763 (5), 11.556 (2)
β (°)	106.41 (3)
V (Å³)	2249.9 (11)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.32
Crystal size (mm)	0.35 × 0.20 × 0.01

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	10097, 9844, 5567
R_int	0.039
(sin θ/λ)_max (Å⁻¹)	0.806

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.052, 0.141, 1.02
No. of reflections	9844
No. of parameters	295
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)	0.50, −0.51

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS86 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).