An oxonium hydrogen sulfate of 3a,6a-diphenyl­glycoluril

In the title compound, (5-oxo-3a,6a-diphenyl­perhydro­imidazo[4,5-d]imidazol-2-ylidene)oxonium hydrogen sulfate, C₁₆H₁₅N₄O₂⁺·HSO₄⁻, the asymmetric unit contains a hydrogen sulfate anion and a 3a,6a-diphenyl­glycoluril oxonium cation. The hydrogen sulfate anion is joined to the oxonium cation via a strong O—H...O hydrogen bond (H...O = 1.69 Å). The crystal packing is mainly dominated by inter­actions involving the hydrogen sulfate anion. The diphenyl­glycoluril oxonium cations also self-assemble through N—H...O hydrogen bonds, forming mol­ecular chains along the [001] vector. Four intra­molecular C—H...N hydrogen bonds are observed, having an S(5) motif.

S1. Comment

Glycoluril and its derivatives, formed in the condensation reaction of two equivalents of urea with one equivalent of glyoxal (Petersen, 1973), have attracted a great deal of attention recently because of wider developments in the fields of cucurbituril chemistry (Freeman et al., 1981; Kim et al., 2000; Lee et al., 2003), anion sensors (Kang et al., 2004; Kang & Kim, 2005) and materials (Kölbel & Menger, 2001). Thus, various glycoluril derivatives have been synthesized and reported (Wu et al., 2002; Burnett et al., 2003). As part of this study of cucurbituril chemistry to prepare new cucurbiturils, we synthesized the title compound, (I). Although many crystal structures of glycoluril and its derivatives have been reported to date (Xu et al., 1994; Wu et al., 2002; Fettinger et al., 2003, 2004; Creaven et al., 2004), and Moon and co-workers have reported the co-crystallized structure of the title organic compound with pyridine (Moon et al., 2003), this is the first report of the new and interesting structure of (I).

In (I), the asymmetric unit contains a hydrogen sulfate anion and a 3a,6a-diphenylglycoluril oxonium cation (Fig. 1). Carbonyl atom O2 is protonated, forming the oxonium ion. The H atoms bonded to atoms O5 and O2 were found directly in the difference Fourier map and positioned correctly, and are not disordered over O1 or other atoms of the HSO₄ group. Geometric differences are observed between the unprotonated atom O1 and the oxonium atom O2: the C4═O2 bond of 1.279 (4) Å is significantly longer than the C3═ O1 bond of 1.245 (4) Å. Furthermore, the two tetrahydroimidazole rings differ in their geometric structures (Table 1). The C1—C2 distance of 1.624 (5) Å is significantly longer? than that of 1.604 (3) Å reported by Moon et al. (2003). The two tetrahydroimidazole rings form a dihedral angle of 65.51 (1)°.

Owing to the peculiar spatial arrangement of the crystal structure of (I), four intramolecular C—H···N hydrogen bonds (Afonin et al., 2002) [Please cite unique reference] are formed, with the aromatic CH groups acting as donors (Table 2). These have a common motif of S(5) (Bernstein et al., 1995), which was also found in the structures reported by Moon et al. (2003). The C5—C2—C1—C11 torsion angle is 13.4 (4)°, the C16—C11—C2—C1 and C12—C11—C2—C1 torsion angles are −94.1 (4) and 83.1 (4)°, respectively, and the C2—C1—C5—C6 and C2—C1—C5—C10 torsion angles are −94.0 (4) and 83.2 (4)°, respectively.

There is an intramolecular π–π interaction, as elucidated by PLATON (Spek, 2003), between the two phenyl ring planes, with a centroid-to-centroid distance of 4.058 (3) Å; the corresponding distance is 4.108 (2) Å in Moon's crystal structure.

The geometric parameters of the hydrogen sulfate anion in (I) are consistent with those reported by Hemamalini et al. (2005). The O—S—O bond angles of the sulfate group, in the range 103.46 (16)–113.15 (17)°, indicate a distorted tetrahedron. The HSO₄⁻ anion is anchored to the diphenylglycoluril oxonium cation by a strong O—H···O hydrogen bond, indicated by the H···O distance of 1.69 Å, with an O—H···O angle of 165°. As well as this strong interaction, the hydrogen sulfate anion is hydrogen bonded to five diphenylglycoluril molecules via O—H···O, N—H···O and C—H···O interactions (Fig. 2 and Table 2). These interactions involving the hydrogen sulfate anion dominate the crystal packing of (I) in a way that is distinctly different from the packing of glycoluril and its derivatives published previously, where hydrogen-bonded tapes were formed (Xu et al., 1994; Wu et al., 2002; Moon et al., 2003). In addition, there is also an N3—H3···O1 hydrogen bond, with atom N3 of one glycoluril moiety as donor and carbonyl atom O1 of the other glycoluril moiety as acceptor, which links the molecules of (I) into an infinite one-dimensional chain along the [001] vector. All these interactions form a network of hydrogen-bonded hydrophilic zones, separating hydrophobic zones composed of the phenyl groups, similar to the structure described by Moon (Fig. 3).

In conclusion, we have obtained an interesting crystal structure of diphenylglycoluril hydrogen sulfate oxonium from its sulfuric acid solution. X-ray analysis demonstrates that the crystal adopts a different packing from the extensive hydrogen-bonding networks reported previously, because of the presence of the hydrogen sulfate.

S2. Experimental

Compound (I) (100 mg) was dissolved in an aqueous solution of H₂SO₄ (1 M, 1 ml). The solution was allowed to evaporate slowly at room temperature over one week. Colourless crystals of (I) suitable for X-ray crystallography were collected.

S3. Refinement

All H atoms were found by difference Fourier synthesis and fixed on their parent atoms, with U_iso(H) values set to 1.5U_eq(parent atom) for O atoms and 1.2U_eq(parent atom) for other H atoms. The C—H distances were fixed in the range 0.93–0.99 Å, O—H distances were fixed at 0.83 Å and N—H distances were fixed at 0.87 Å. The R factor of 0.077 may be due to random protonatation of the diphenylglycoluril by the hydrogen sulfate to form the oxonium ion.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A view of the molecular structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The hydrogen sulfate anion of (I) and its surroudings. Hydrogen-bonding interactions are indicated by dotted lines. Only atoms involved in the hydrogen bonds are labelled.
	Fig. 3. A packing diagram for (I), viewed down the c axis.

cis-1,5-Diphenyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione hydrogen sulfate5-oxo-3a,6a-diphenylperhydroimidazo[4,5-d]imidazol-2-yloxonium hydrogen sulfate

Crystal data

C16H15N4O2^+·HO4S^−	F(000) = 816
Mr = 392.39	Dx = 1.452 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7302 reflections
a = 8.4695 (18) Å	θ = 2.4–26.9°
b = 20.686 (4) Å	µ = 0.22 mm^−1
c = 10.269 (2) Å	T = 203 K
β = 93.655 (3)°	Block, colourless
V = 1795.5 (7) Å^3	0.50 × 0.20 × 0.10 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	3160 independent reflections
Radiation source: fine-focus sealed tube	2888 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
Detector resolution: 100x100 microns pixels mm^-1	θmax = 25.0°, θmin = 2.0°
ω scans	h = −5→10
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −23→24
Tmin = 0.897, Tmax = 0.978	l = −12→12
7302 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.077	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.149	H-atom parameters constrained
S = 1.28	w = 1/[σ^2(Fo^2) + (0.0348P)^2 + 2.3309P] where P = (Fo^2 + 2Fc^2)/3
3160 reflections	(Δ/σ)max < 0.001
250 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.36 e Å^−3

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 > 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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.6774 (5)	0.33269 (17)	0.2813 (3)	0.0249 (8)
C10	0.8728 (5)	0.34823 (19)	0.4735 (4)	0.0331 (9)
C11	0.8477 (5)	0.41951 (17)	0.1621 (4)	0.0298 (9)
C12	0.9328 (6)	0.3903 (2)	0.0674 (5)	0.0498 (12)
C13	1.0861 (7)	0.4104 (3)	0.0484 (6)	0.0659 (16)
C14	1.1525 (6)	0.4593 (3)	0.1220 (7)	0.0688 (18)
C15	1.0707 (7)	0.4879 (3)	0.2157 (6)	0.0642 (16)
C16	0.9182 (5)	0.4683 (2)	0.2356 (5)	0.0442 (11)
C2	0.6839 (5)	0.39505 (16)	0.1858 (3)	0.0257 (8)
C3	0.5727 (5)	0.30628 (17)	0.0731 (3)	0.0254 (8)
C4	0.5160 (5)	0.41521 (17)	0.3478 (3)	0.0259 (9)
C5	0.8297 (5)	0.31624 (17)	0.3584 (3)	0.0274 (9)
C6	0.9317 (6)	0.2719 (2)	0.3118 (5)	0.0527 (13)
C7	1.0751 (7)	0.2601 (3)	0.3786 (6)	0.0706 (17)
C8	1.1176 (6)	0.2922 (3)	0.4929 (5)	0.0559 (14)
C9	1.0172 (5)	0.3359 (2)	0.5402 (4)	0.0441 (11)
N1	0.6001 (4)	0.36989 (14)	0.0702 (3)	0.0294 (8)
N2	0.6223 (4)	0.28321 (14)	0.1906 (3)	0.0305 (8)
N3	0.5553 (4)	0.35370 (14)	0.3670 (3)	0.0258 (7)
N4	0.5903 (4)	0.44128 (14)	0.2517 (3)	0.0272 (7)
O1	0.5117 (3)	0.27309 (11)	−0.0179 (2)	0.0312 (6)
O2	0.4207 (3)	0.44896 (12)	0.4116 (2)	0.0330 (7)
O3	0.3492 (3)	0.41119 (13)	0.6309 (2)	0.0341 (7)
O4	0.5949 (4)	0.35524 (13)	0.6834 (3)	0.0407 (8)
O5	0.3611 (3)	0.33289 (13)	0.7975 (3)	0.0370 (7)
O6	0.4994 (4)	0.43406 (12)	0.8316 (2)	0.0349 (7)
S1	0.45866 (12)	0.38556 (4)	0.73304 (9)	0.0251 (3)
H1	0.5698	0.3941	0.0040	0.035*
H10	0.8034	0.3786	0.5069	0.040*
H12	0.8868	0.3568	0.0160	0.057 (15)*
H13	1.1441	0.3903	−0.0153	0.079*
H14	1.2556	0.4732	0.1079	0.083*
H15	1.1178	0.5212	0.2670	0.077*
H16	0.8620	0.4886	0.3002	0.046 (13)*
H2	0.6214	0.2423	0.2102	0.055 (14)*
H2A	0.4023	0.4299	0.4801	0.050*
H3	0.5136	0.3288	0.4238	0.031*
H4	0.5834	0.4819	0.2305	0.033*
H5	0.4180	0.3138	0.8541	0.055*
H6	0.9039	0.2495	0.2341	0.063*
H7	1.1449	0.2298	0.3457	0.087 (19)*
H8	1.2156	0.2837	0.5378	0.067*
H9	1.0453	0.3580	0.6183	0.053*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.032 (2)	0.0205 (18)	0.0222 (18)	−0.0019 (16)	0.0027 (17)	0.0034 (15)
C10	0.036 (2)	0.032 (2)	0.032 (2)	0.0023 (19)	0.0016 (19)	−0.0010 (17)
C11	0.037 (2)	0.0206 (19)	0.032 (2)	−0.0001 (17)	−0.0031 (18)	0.0085 (16)
C12	0.050 (3)	0.046 (3)	0.055 (3)	−0.002 (2)	0.015 (2)	0.001 (2)
C13	0.052 (3)	0.072 (4)	0.077 (4)	0.008 (3)	0.029 (3)	0.018 (3)
C14	0.035 (3)	0.071 (4)	0.099 (5)	−0.006 (3)	0.000 (3)	0.042 (4)
C15	0.053 (3)	0.057 (3)	0.080 (4)	−0.025 (3)	−0.016 (3)	0.013 (3)
C16	0.043 (3)	0.040 (2)	0.049 (3)	−0.011 (2)	−0.001 (2)	0.005 (2)
C2	0.038 (2)	0.0122 (17)	0.0265 (19)	−0.0016 (16)	0.0014 (17)	−0.0001 (14)
C3	0.034 (2)	0.0182 (19)	0.0235 (19)	0.0017 (17)	0.0006 (17)	0.0012 (15)
C4	0.033 (2)	0.0238 (19)	0.0193 (18)	0.0031 (17)	−0.0075 (17)	−0.0050 (15)
C5	0.035 (2)	0.0220 (19)	0.025 (2)	0.0005 (17)	0.0031 (17)	0.0046 (15)
C6	0.054 (3)	0.046 (3)	0.057 (3)	0.018 (2)	−0.005 (3)	−0.013 (2)
C7	0.051 (3)	0.075 (4)	0.085 (4)	0.036 (3)	−0.008 (3)	−0.014 (3)
C8	0.039 (3)	0.062 (3)	0.065 (3)	0.009 (3)	−0.014 (3)	0.010 (3)
C9	0.042 (3)	0.054 (3)	0.035 (2)	−0.004 (2)	−0.004 (2)	0.002 (2)
N1	0.049 (2)	0.0177 (16)	0.0205 (15)	−0.0005 (15)	−0.0066 (15)	0.0037 (12)
N2	0.047 (2)	0.0164 (16)	0.0271 (17)	−0.0014 (15)	−0.0033 (16)	0.0027 (13)
N3	0.0308 (18)	0.0223 (16)	0.0245 (16)	0.0002 (14)	0.0040 (14)	0.0075 (13)
N4	0.041 (2)	0.0146 (15)	0.0272 (17)	0.0017 (14)	0.0072 (15)	0.0030 (13)
O1	0.0464 (17)	0.0200 (13)	0.0267 (14)	−0.0027 (12)	−0.0027 (13)	−0.0040 (11)
O2	0.0447 (18)	0.0281 (14)	0.0266 (14)	0.0096 (13)	0.0056 (13)	0.0014 (11)
O3	0.0400 (17)	0.0358 (16)	0.0262 (14)	−0.0010 (13)	−0.0011 (13)	0.0030 (11)
O4	0.0486 (19)	0.0255 (14)	0.0498 (18)	0.0058 (14)	0.0162 (15)	0.0028 (13)
O5	0.0412 (17)	0.0335 (16)	0.0356 (16)	−0.0073 (14)	−0.0026 (14)	0.0107 (12)
O6	0.058 (2)	0.0179 (13)	0.0277 (14)	0.0033 (13)	−0.0053 (14)	0.0020 (11)
S1	0.0325 (5)	0.0180 (4)	0.0249 (5)	−0.0001 (4)	0.0030 (4)	0.0000 (4)

Geometric parameters (Å, º)

S1—O4	1.435 (3)	C11—C12	1.386 (6)
S1—O6	1.451 (3)	C11—C2	1.511 (5)
S1—O3	1.455 (3)	C5—C6	1.367 (6)
S1—O5	1.542 (3)	C5—C10	1.383 (5)
O1—C3	1.245 (4)	C10—C9	1.387 (6)
O2—C4	1.279 (4)	C10—H10	0.9400
O2—H2A	0.8300	C12—C13	1.389 (7)
N4—C4	1.319 (5)	C12—H12	0.9400
N4—C2	1.439 (4)	C6—C7	1.378 (7)
N4—H4	0.8700	C6—H6	0.9400
N2—C3	1.340 (4)	C9—C8	1.353 (7)
N2—C1	1.442 (5)	C9—H9	0.9400
N2—H2	0.8700	C16—C15	1.381 (7)
O5—H5	0.8300	C16—H16	0.9400
N1—C3	1.337 (4)	C15—C14	1.357 (8)
N1—C2	1.441 (5)	C15—H15	0.9400
N1—H1	0.8700	C8—C7	1.376 (7)
N3—C4	1.327 (4)	C8—H8	0.9400
N3—C1	1.465 (5)	C7—H7	0.9400
N3—H3	0.8700	C14—C13	1.361 (8)
C1—C5	1.509 (5)	C14—H14	0.9400
C1—C2	1.624 (5)	C13—H13	0.9400
C11—C16	1.374 (6)
O3—S1—O5	103.46 (16)	N1—C3—N2	109.0 (3)
O4—S1—O3	113.15 (17)	N4—C2—N1	111.7 (3)
O4—S1—O5	107.98 (16)	N4—C2—C11	113.1 (3)
O4—S1—O6	112.89 (18)	N1—C2—C11	113.4 (3)
O6—S1—O3	111.29 (16)	N4—C2—C1	101.7 (3)
O6—S1—O5	107.42 (16)	N1—C2—C1	100.2 (3)
C4—O2—H2A	109.5	C11—C2—C1	115.5 (3)
C4—N4—C2	112.6 (3)	C5—C10—C9	120.7 (4)
C4—N4—H4	123.7	C5—C10—H10	119.7
C2—N4—H4	123.7	C9—C10—H10	119.7
C3—N2—C1	113.5 (3)	C11—C12—C13	120.0 (5)
C3—N2—H2	123.2	C11—C12—H12	120.0
C1—N2—H2	123.2	C13—C12—H12	120.0
S1—O5—H5	109.5	C5—C6—C7	120.0 (5)
C3—N1—C2	114.5 (3)	C5—C6—H6	120.0
C3—N1—H1	122.8	C7—C6—H6	120.0
C2—N1—H1	122.8	C8—C9—C10	120.1 (4)
C4—N3—C1	112.0 (3)	C8—C9—H9	120.0
C4—N3—H3	124.0	C10—C9—H9	120.0
C1—N3—H3	124.0	C11—C16—C15	120.8 (5)
N2—C1—N3	112.8 (3)	C11—C16—H16	119.6
N2—C1—C5	114.2 (3)	C15—C16—H16	119.6
N3—C1—C5	111.3 (3)	C14—C15—C16	120.1 (5)
N2—C1—C2	101.3 (3)	C14—C15—H15	120.0
N3—C1—C2	100.4 (3)	C16—C15—H15	120.0
C5—C1—C2	115.8 (3)	C9—C8—C7	119.5 (5)
O2—C4—N4	120.4 (3)	C9—C8—H8	120.3
O2—C4—N3	127.5 (3)	C7—C8—H8	120.3
N4—C4—N3	112.1 (3)	C8—C7—C6	120.9 (5)
C16—C11—C12	118.6 (4)	C8—C7—H7	119.5
C16—C11—C2	122.0 (4)	C6—C7—H7	119.5
C12—C11—C2	119.4 (4)	C15—C14—C13	120.4 (5)
C6—C5—C10	118.8 (4)	C15—C14—H14	119.8
C6—C5—C1	120.4 (4)	C13—C14—H14	119.8
C10—C5—C1	120.7 (3)	C14—C13—C12	120.1 (5)
O1—C3—N1	126.2 (3)	C14—C13—H13	119.9
O1—C3—N2	124.8 (3)	C12—C13—H13	119.9
C3—N2—C1—N3	96.0 (4)	C12—C11—C2—N1	−31.7 (5)
C3—N2—C1—C5	−135.6 (3)	C16—C11—C2—C1	−94.1 (4)
C3—N2—C1—C2	−10.4 (4)	C12—C11—C2—C1	83.1 (4)
C4—N3—C1—N2	−115.8 (3)	N2—C1—C2—N4	126.5 (3)
C4—N3—C1—C5	114.4 (3)	N3—C1—C2—N4	10.5 (3)
C4—N3—C1—C2	−8.8 (4)	C5—C1—C2—N4	−109.4 (3)
C2—N4—C4—O2	−176.1 (3)	N2—C1—C2—N1	11.6 (3)
C2—N4—C4—N3	4.9 (4)	N3—C1—C2—N1	−104.4 (3)
C1—N3—C4—O2	−175.6 (4)	C5—C1—C2—N1	135.6 (3)
C1—N3—C4—N4	3.3 (4)	N2—C1—C2—C11	−110.6 (3)
N2—C1—C5—C6	23.1 (5)	N3—C1—C2—C11	133.4 (3)
N3—C1—C5—C6	152.2 (4)	C5—C1—C2—C11	13.4 (4)
C2—C1—C5—C6	−94.0 (4)	C6—C5—C10—C9	0.4 (6)
N2—C1—C5—C10	−160.6 (3)	C1—C5—C10—C9	−176.0 (4)
N3—C1—C5—C10	−31.5 (5)	C16—C11—C12—C13	0.1 (7)
C2—C1—C5—C10	82.3 (4)	C2—C11—C12—C13	−177.2 (4)
C2—N1—C3—O1	−175.2 (4)	C10—C5—C6—C7	−0.5 (7)
C2—N1—C3—N2	4.6 (5)	C1—C5—C6—C7	175.9 (5)
C1—N2—C3—O1	−175.5 (4)	C5—C10—C9—C8	−0.1 (7)
C1—N2—C3—N1	4.7 (5)	C12—C11—C16—C15	0.0 (6)
C4—N4—C2—N1	96.2 (4)	C2—C11—C16—C15	177.2 (4)
C4—N4—C2—C11	−134.3 (3)	C11—C16—C15—C14	0.4 (7)
C4—N4—C2—C1	−9.8 (4)	C10—C9—C8—C7	−0.1 (8)
C3—N1—C2—N4	−117.4 (3)	C9—C8—C7—C6	−0.1 (9)
C3—N1—C2—C11	113.3 (4)	C5—C6—C7—C8	0.4 (9)
C3—N1—C2—C1	−10.3 (4)	C16—C15—C14—C13	−1.0 (8)
C16—C11—C2—N4	22.5 (5)	C15—C14—C13—C12	1.0 (8)
C12—C11—C2—N4	−160.3 (3)	C11—C12—C13—C14	−0.6 (8)
C16—C11—C2—N1	151.1 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···N2	0.94	2.50	2.838 (6)	101
C10—H10···N3	0.94	2.52	2.839 (5)	100
C12—H12···N1	0.94	2.54	2.851 (6)	100
C16—H16···N4	0.94	2.52	2.849 (6)	101
N1—H1···O6^i	0.87	2.01	2.869 (4)	169
N2—H2···O4^ii	0.87	2.05	2.874 (4)	158
N3—H3···O1^iii	0.87	2.19	2.910 (4)	140
N4—H4···O6^iv	0.87	1.96	2.806 (4)	162
O5—H5···O1^v	0.83	1.71	2.538 (4)	172
C7—H7···O5^vi	0.94	2.32	3.244 (6)	166
O2—H2A···O3	0.83	1.69	2.495 (4)	165

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