Zoledronate complexes. I. Poly[[μ₂-aqua­[μ₃-1-hydr­oxy-2-(1H,3H-imidazol-3-ium-1-yl)ethyl­idenediphosphon­ato]potassium(I)] monohydrate]

The title compound, {[K(C₅H₉N₂O₇P₂)(H₂O)]·H₂O}_n, is polymeric and consists of layers parallel to (001) inter­connected by hydrogen-bonding and π–π inter­actions. The K⁺ cation is eightfold coordinated in a KO₈ environment by O atoms from three different chelating zoledronate units and two coordinated water mol­ecules. The zoledronate group presents its usual zwitterionic character, with negative charges in the singly protonated phospho­nate groups and a positive charge at the protonated imidazole N atom. The anion binds to three different K⁺ cations in a (so far unreported) triply chelating manner. Intra- and inter­planar inter­actions are enhanced by a variety of hydrogen bonds involving all available O—H and N—H donors. A strong imidazole–phosphon­ate C—H...O inter­action is present in the structure.

S1. Comment

Bisphosphonates (BPs) constitute an extensive family of compounds (including etidronate, pamidronate, zoledronate etc.) characterized by a P—C—P backbone and which can be considered stable analogues of naturally occurring pyrophosphates. The main interest in BP-derived compounds lies in the outstanding role they play in clinical medicine due to the fact that several BPs have been established as the standard treatment for various diseases associated with excessive bone resorption, such as Paget's disease, myeloma, bone metastases, osteoporosis etc. (Fleisch, 2000; Ross et al., 2004; Smith, 2005; Ralston et al., 1989; Reid et al., 2005; Rauch & Glorieux, 2005; Chesnut et al., 2004). The P—C—P base structure allows BPs to bind to many metallic cations, in particular mono- and divalent metal ions, and as a result they can adhere to bone surfaces in vivo (Fleisch et al., 1968). Third-generation BPs are characterized by having an N-containing cyclic side chain (in the case of zoledronate, an imidazole group) which tends to make them most effective for medical treatment (Green et al., 1994). Much work has been devoted to structural, magnetic and other studies of derivatives of these sorts of compounds; two arbitrarily chosen recent works on the subject are Stahl et al. (2006) and Zhang et al. (2007). In particular, a large number of metal derivatives of etidronate and pamidronate are known where the bisphosphonate ligand displays a variety of coordination modes, but surprisingly, relatively few metal derivatives of zoledronic acid have been structurally characterized so far, in spite of its utmost importance as a pharmacological drug, viz. Co [Cambridge Structural Database (CSD; Version?; Allen, 2002) refcodes VIMXEV and VIMXOF; References?], Ni (VIMXIZ and VIMXUL; Cao et al., 2007); Cu (DOGYEE, DOGYII, DOGYOO and DOGYUU; Cao et al., 2008); and Zn (Not yet in the CSD [Any update?]; Freire & Vega, 2009a,b). In particular, no such reports have been published to date for alkaline metals. In an attempt to fill this gap in the literature, and as the first report in a series on zoledronate complexes of mono- and divalent alkaline cations, we present here the crystal structure of the title potassium compound, (I).

The structure of (I) is polymeric and consists of layers parallel to (001), interconnected by hydrogen-bonding and π–π interactions. Fig. 1 shows an ellipsoid plot of the elemental unit of (I), which consists of a K⁺ centre (K1), a zoledronate^-1 zwitterion, one aqua ligand (O1W) and one solvent water molecule (O2W). The K⁺ cation is eight-coordinated in a KO₈ environment by O atoms from three different chelating zoledronate units and two coordinated water molecules. This eightfold coordination is the most common for the many KO_n arrangements reported in the literature, where a diversity of compounds with n as low as 3 and as high as 12 can be found.

The K—O bond distances in (I) (Table 1) fall well within the (normally broad) range observed in eight-coordinated potassium complexes, which display upper and lower limits of 2.62 and 3.52 Å, respectively, in the ca 350 cases reported in the 2009 version of the CSD.

The zoledronate group presents its usual zwitterionic character, with negative charges in the singly protonated phosphonate groups and a positive charge at the protonated imidazole atom N2. The resulting single negative charge provides charge balance for the cationic centre.

Bond distances in the imidazole ring suggest an approximately equal charge distribution on the two N atoms, with two short [C3—N1 = 1.330 (2) and C3—N2 = 1.323 (2) Å] and two long [C4—N2 = 1.373 (3) and C5—N1 = 1.384 (2) Å] bonds, implying partial double-bond character between atoms C3 and N1/N2, and essentially single-bond character at N1—C5 and N2—C4. The remaining double bond in the ring is found at C4—C5 [1.356 (3) Å].

Both phosphonates are singly protonated, at O13 and O22, respectively (Fig. 1), and this fact is clearly reflected in the corresponding P—O lengthening (about 0.05 Å) relative to the remaining two P—O pairs in each phosphonate [P1—O13 = 1.5567 (14), P1—O11 = 1.5034 (14) and P1—O12 = 1.5082 (14) Å, and P2—O22 = 1.5658 (14), P2—O21 = 1.5121 (14) and P2—O23 = 1.5030 (14) Å].

The anion binds to three different K⁺ cations in a triply chelating manner, one of the bites (O22—P2—O23) being internal to one phosphonate centre and the remaining two bites involving one O atom from each phosphonate centre (O11—P1—C1—P2—O21 and O13—P1—C1—P2—O22). Even though this binding mode (entry f in Fig. 2) has already been observed in other related bisphosphonates (see, for instance, Stahl et al., 2006), it is new for the zoledronate anion and adds to the diversity shown in the few zoledronate complexes described so far in the literature, spanning a wide range in both µ values (1 to 4) [Definition of µ needed?] and denticity (2 to 7) (Fig. 2).

Atoms O22 and O1W are shared by two different symmetry-related cations, resulting in a concatenated chain of centrosymmetric K₂O₂ loops running along a (shaded in Figs. 3 and 4). The K···K distances in these linear arrays are not particularly short: 4.5062 (15) Å in the bridge mediated by atom O1W and 4.7034 (19) Å in that due to atom O22, compared with the mean value of 3.85 Å in similar K₂O₂ loops in the literature. These chains are interconnected along b by multiple phosphonate links to form a tightly bound two-dimensional hydrophilic structure parallel to (001) (Fig. 3). The hydrophobic aromatic side chains in turn evolve outwards on both sides of the plane and engage in close π–π contacts with their neighbouring counterparts (Fig. 4 and Table 2). Intra- and interplanar interactions are in turn enhanced by a variety of hydrogen bonds involving all the available O—H and N—H donors (Table 3) and where some of the phosphonate O atoms acting as acceptors receive as many as three strong interactions (e.g. atom O23). Incidentally, one of these contacts, a non-conventional C—H···O hydrogen bond involving an imidazole C—H group and a phosphonate O atom, appeared to be rather short for this type of usually very weak interaction (H···O = 2.36 Å; Table 3, last entry). However, data mining in the CSD showed that even if this distance is in fact short compared with those obtained for a general unrestricted C—H···O interaction [such an open search showed that less than 3% of the reported H···O values lie below the target of 2.36 Å found in (I)], it does not appear so singular when compared with values found in complexes containing similar C—H donors with enhanced acidity (due to N-atom vicinity, as in imidazole, pyridine etc.) and eager O acceptors (as in phosphates, phosphonates etc.) which returned a much higher rate of short C—H···O contacts. In particular, a search among zoledronate complexes alone provided many occurrences comparable with those in (I) (e.g. for DOGYEE and DOGYUU, H···O = 2.36 Å) and even smaller distances [VIMXIZ (2.32 Å), VIMXEV (2.30 Å) and DOGYUU (2.24 Å)], confirming that the simultaneous presence of imidazole and biphosphonate appears to be particularly favourable for the occurrence of this kind of strong C—H···O interaction.

S2. Experimental

Crystals of (I) were synthesized by neutralization of a solution of zoledronic acid (provided by GADOR ARGENTINA S.A.) with a KOH solution in a 1:1 stoichometric ratio. After a few days, large colourless blocks of (I) were obtained, suitable for X-ray diffraction.

S3. Refinement

H atoms attached to O and N atoms were found in a difference Fourier map, further idealized (O—H = 0.82 and N—H = 0.87 Å) and finally allowed to ride. H atoms attached to C atoms were placed in calculated positions (C—H = 0.93 and C—H₂ = 0.97 Å) and allowed to ride. For all H atoms, U_iso(H) = 1.2 or 1.5U_eq(parent).

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); cell refinement: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); data reduction: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures

	Fig. 1. Ellipsoid plot of (I), showing the atom-numnbering scheme. Full lines and bonds indicate the asymmetric unit, and empty ellipsoids and bonds the symmetry-related part completing the coordination polyhedron. Displacement ellipsoids are drawn at the ??% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) x, y + 1, z; (ii) -x + 1, -y + 2, -z; (iii) -x + 2, -y + 2, -z; (iv) x, y - 1, z.]
	Fig. 2. The reported coordination schemes found for zoledronate. (a) Freire & Vega (2009a,b); Cao et al. (2007, 2008). (b), (c), (d) Cao et al. (2008). (e) Cao et al. (2007). (f) This work.
	Fig. 3. A packing diagram for (I), viewed along c and displaying the two-dimensional structure parallel to (001). Note the ···K—O2—K—O2—K··· chains running along b. O22-bridged loops are shown in dark grey and O1W-bridged ones in light grey. Pendant imidazole and hydroxyl groups, and H atoms, have been omitted for clarity.
	Fig. 4. A packing diagram for (I), viewed along a and showing the planes in projection. Note the overlap of neighbouring imidazole rings.

Poly[[µ₂-aqua[µ₃-1-hydroxy-2-(1H,3H-imidazol-3-ium-1- yl)ethylidenediphosphonato]potassium(I)] monohydrate]

Crystal data

[K(C5H9N2O7P2)(H2O)]·H2O	Z = 2
Mr = 346.21	F(000) = 356
Triclinic, P1	Dx = 1.824 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.9610 (14) Å	Cell parameters from 25 reflections
b = 7.0380 (14) Å	θ = 7.5–12.5°
c = 13.322 (3) Å	µ = 0.72 mm^−1
α = 94.82 (2)°	T = 295 K
β = 103.75 (3)°	Block, colourless
γ = 92.58 (2)°	0.32 × 0.30 × 0.26 mm
V = 630.3 (2) Å^3

Data collection

Rigaku AFC-6S diffractometer	2333 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.019
Graphite monochromator	θmax = 26.0°, θmin = 1.6°
ω/2θ scans	h = −8→8
Absorption correction: ψ scan (North et al., 1968)	k = −1→8
Tmin = 0.78, Tmax = 0.83	l = −16→16
3124 measured reflections	3 standard reflections every 150 reflections
2482 independent reflections	intensity decay: 1%

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)] = 0.026	H-atom parameters constrained
wR(F^2) = 0.070	w = 1/[σ^2(Fo^2) + (0.028P)^2 + 0.4297P] where P = (Fo^2 + 2Fc^2)/3
S = 1.12	(Δ/σ)max < 0.001
2482 reflections	Δρmax = 0.44 e Å^−3
181 parameters	Δρmin = −0.31 e Å^−3
0 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: 0.112 (4)

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	0.79017 (7)	1.20460 (6)	0.04721 (4)	0.03328 (14)
P1	0.42467 (6)	0.49289 (6)	0.19068 (3)	0.01914 (13)
O11	0.4905 (2)	0.3654 (2)	0.11067 (11)	0.0335 (3)
O12	0.36040 (19)	0.38748 (19)	0.27244 (10)	0.0295 (3)
O13	0.26050 (19)	0.6207 (2)	0.13818 (11)	0.0303 (3)
H13	0.1510	0.6002	0.1494	0.087 (12)*
P2	0.78598 (6)	0.74636 (6)	0.16772 (3)	0.01890 (13)
O21	0.90172 (18)	0.58028 (18)	0.14159 (11)	0.0271 (3)
O22	0.63208 (19)	0.80226 (18)	0.07023 (9)	0.0254 (3)
H22	0.6032	0.7312	0.0161	0.064 (9)*
O23	0.90917 (19)	0.92362 (19)	0.22082 (10)	0.0291 (3)
O1	0.76594 (18)	0.57690 (18)	0.33804 (9)	0.0241 (3)
H1	0.8244	0.4943	0.3126	0.043 (7)*
C1	0.6368 (2)	0.6646 (2)	0.25665 (12)	0.0173 (3)
C2	0.5700 (3)	0.8428 (2)	0.31097 (13)	0.0223 (4)
H2A	0.6839	0.9327	0.3387	0.027*
H2B	0.4755	0.9042	0.2602	0.027*
C3	0.5790 (3)	0.7566 (3)	0.48896 (14)	0.0249 (4)
H3	0.7163	0.7578	0.5110	0.030*
C4	0.2628 (3)	0.7265 (3)	0.48642 (16)	0.0318 (4)
H4	0.1461	0.7032	0.5071	0.038*
C5	0.2782 (3)	0.7791 (3)	0.39290 (15)	0.0274 (4)
H5	0.1741	0.7991	0.3373	0.033*
N1	0.4784 (2)	0.7973 (2)	0.39607 (11)	0.0210 (3)
N2	0.4522 (3)	0.7142 (2)	0.54492 (12)	0.0286 (4)
H2	0.4884	0.6807	0.6078	0.049 (7)*
O1W	0.8299 (2)	0.9435 (2)	−0.10922 (14)	0.0429 (4)
H1WA	0.8804	0.9891	−0.1523	0.062 (9)*
H1WB	0.7462	0.8633	−0.1441	0.100 (14)*
O2W	0.0079 (2)	0.2820 (2)	0.32857 (12)	0.0369 (3)
H2WA	0.1074	0.3211	0.3118	0.058 (9)*
H2WB	−0.0349	0.1777	0.2971	0.062 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.0328 (2)	0.0335 (2)	0.0367 (3)	0.01104 (17)	0.01212 (18)	0.00611 (18)
P1	0.0164 (2)	0.0215 (2)	0.0194 (2)	−0.00089 (16)	0.00453 (16)	0.00224 (16)
O11	0.0252 (7)	0.0404 (8)	0.0316 (7)	0.0004 (6)	0.0061 (6)	−0.0126 (6)
O12	0.0261 (7)	0.0311 (7)	0.0314 (7)	−0.0060 (5)	0.0061 (5)	0.0111 (6)
O13	0.0161 (6)	0.0375 (8)	0.0391 (8)	0.0031 (5)	0.0055 (5)	0.0176 (6)
P2	0.0160 (2)	0.0217 (2)	0.0198 (2)	−0.00086 (16)	0.00636 (16)	0.00252 (16)
O21	0.0189 (6)	0.0286 (7)	0.0364 (7)	0.0035 (5)	0.0113 (5)	0.0025 (5)
O22	0.0280 (7)	0.0293 (7)	0.0192 (6)	0.0053 (5)	0.0051 (5)	0.0041 (5)
O23	0.0274 (7)	0.0293 (7)	0.0299 (7)	−0.0088 (5)	0.0087 (5)	−0.0008 (5)
O1	0.0237 (6)	0.0291 (7)	0.0198 (6)	0.0093 (5)	0.0036 (5)	0.0054 (5)
C1	0.0165 (8)	0.0200 (8)	0.0158 (7)	0.0016 (6)	0.0042 (6)	0.0035 (6)
C2	0.0263 (9)	0.0215 (8)	0.0221 (8)	0.0021 (7)	0.0111 (7)	0.0033 (7)
C3	0.0271 (9)	0.0253 (9)	0.0222 (9)	0.0048 (7)	0.0056 (7)	0.0007 (7)
C4	0.0309 (10)	0.0361 (11)	0.0325 (10)	0.0017 (8)	0.0159 (8)	0.0031 (8)
C5	0.0218 (9)	0.0353 (10)	0.0259 (9)	0.0047 (7)	0.0073 (7)	0.0014 (8)
N1	0.0216 (7)	0.0228 (7)	0.0196 (7)	0.0037 (6)	0.0071 (6)	0.0017 (6)
N2	0.0379 (9)	0.0289 (8)	0.0216 (8)	0.0048 (7)	0.0110 (7)	0.0053 (6)
O1W	0.0439 (9)	0.0328 (8)	0.0551 (10)	−0.0094 (7)	0.0225 (8)	−0.0027 (7)
O2W	0.0356 (8)	0.0313 (8)	0.0480 (9)	0.0009 (6)	0.0201 (7)	0.0000 (7)

Geometric parameters (Å, º)

K1—O11^i	2.6901 (16)	O1—H1	0.8200
K1—O1W	2.7335 (19)	C1—C2	1.541 (2)
K1—O13^ii	2.8053 (16)	C2—N1	1.477 (2)
K1—O21^i	2.8225 (16)	C2—H2A	0.9700
K1—O1W^iii	2.8491 (19)	C2—H2B	0.9700
K1—O22^ii	2.9795 (16)	C3—N2	1.323 (2)
K1—O22	3.0576 (16)	C3—N1	1.330 (2)
K1—O23	3.1546 (17)	C3—H3	0.9300
P1—O11	1.5034 (14)	C4—C5	1.356 (3)
P1—O12	1.5082 (14)	C4—N2	1.373 (3)
P1—O13	1.5567 (14)	C4—H4	0.9300
P1—C1	1.8591 (18)	C5—N1	1.384 (2)
O13—H13	0.8200	C5—H5	0.9300
P2—O23	1.5030 (14)	N2—H2	0.8710
P2—O21	1.5121 (14)	O1W—H1WA	0.8200
P2—O22	1.5658 (14)	O1W—H1WB	0.8200
P2—C1	1.8599 (17)	O2W—H2WA	0.8200
O22—H22	0.8200	O2W—H2WB	0.8200
O1—C1	1.437 (2)
O11^i—K1—O1W	136.86 (5)	P1—O13—K1^ii	130.63 (8)
O11^i—K1—O13^ii	96.34 (5)	P1—O13—H13	115.7
O1W—K1—O13^ii	70.44 (5)	K1^ii—O13—H13	108.2
O11^i—K1—O21^i	68.32 (5)	O23—P2—O21	115.33 (8)
O1W—K1—O21^i	144.40 (5)	O23—P2—O22	108.42 (8)
O13^ii—K1—O21^i	83.83 (5)	O21—P2—O22	112.28 (8)
O11^i—K1—O1W^iii	146.03 (5)	O23—P2—C1	107.63 (8)
O1W—K1—O1W^iii	72.37 (7)	O21—P2—C1	107.03 (8)
O13^ii—K1—O1W^iii	112.80 (5)	O22—P2—C1	105.59 (7)
O21^i—K1—O1W^iii	96.85 (5)	P2—O21—K1^iv	133.42 (7)
O11^i—K1—O22^ii	52.62 (4)	P2—O22—K1^ii	147.90 (7)
O1W—K1—O22^ii	85.14 (5)	P2—O22—K1	102.44 (7)
O13^ii—K1—O22^ii	66.76 (4)	K1^ii—O22—K1	102.35 (5)
O21^i—K1—O22^ii	107.33 (5)	P2—O22—H22	120.9
O1W^iii—K1—O22^ii	155.44 (5)	K1^ii—O22—H22	65.1
O11^i—K1—O22	92.19 (5)	K1—O22—H22	114.3
O1W—K1—O22	67.56 (5)	P2—O23—K1	100.04 (7)
O13^ii—K1—O22	126.27 (5)	C1—O1—H1	109.6
O21^i—K1—O22	146.81 (4)	O1—C1—C2	105.27 (13)
O1W^iii—K1—O22	84.55 (5)	O1—C1—P1	109.55 (11)
O22^ii—K1—O22	77.65 (5)	C2—C1—P1	112.26 (11)
O11^i—K1—O23	99.07 (5)	O1—C1—P2	108.07 (11)
O1W—K1—O23	93.95 (5)	C2—C1—P2	107.97 (11)
O13^ii—K1—O23	163.41 (4)	P1—C1—P2	113.33 (9)
O21^i—K1—O23	107.56 (4)	N1—C2—C1	112.71 (14)
O1W^iii—K1—O23	54.96 (5)	N1—C2—H2A	109.0
O22^ii—K1—O23	118.91 (4)	C1—C2—H2A	109.0
O22—K1—O23	47.22 (4)	N1—C2—H2B	109.0
O11^i—K1—K1^iii	165.24 (4)	C1—C2—H2B	109.0
O1W—K1—K1^iii	37.06 (4)	H2A—C2—H2B	107.8
O13^ii—K1—K1^iii	92.40 (4)	N2—C3—N1	108.98 (16)
O21^i—K1—K1^iii	124.65 (4)	N2—C3—H3	125.5
O1W^iii—K1—K1^iii	35.32 (4)	N1—C3—H3	125.5
O22^ii—K1—K1^iii	121.58 (4)	C5—C4—N2	107.06 (17)
O22—K1—K1^iii	73.05 (3)	C5—C4—H4	126.5
O23—K1—K1^iii	71.26 (3)	N2—C4—H4	126.5
O11^i—K1—K1^ii	68.92 (4)	C4—C5—N1	106.84 (17)
O1W—K1—K1^ii	72.44 (4)	C4—C5—H5	126.6
O13^ii—K1—K1^ii	97.74 (4)	N1—C5—H5	126.6
O21^i—K1—K1^ii	137.11 (4)	C3—N1—C5	108.25 (15)
O1W^iii—K1—K1^ii	120.96 (4)	C3—N1—C2	124.38 (15)
O22^ii—K1—K1^ii	39.42 (3)	C5—N1—C2	127.29 (15)
O22—K1—K1^ii	38.23 (3)	C3—N2—C4	108.88 (16)
O23—K1—K1^ii	82.23 (4)	C3—N2—H2	123.3
K1^iii—K1—K1^ii	98.17 (3)	C4—N2—H2	127.7
O11—P1—O12	113.93 (9)	K1—O1W—K1^iii	107.63 (7)
O11—P1—O13	110.93 (9)	K1—O1W—H1WA	113.9
O12—P1—O13	111.03 (8)	K1^iii—O1W—H1WA	82.1
O11—P1—C1	107.84 (8)	K1—O1W—H1WB	127.9
O12—P1—C1	108.09 (8)	K1^iii—O1W—H1WB	112.4
O13—P1—C1	104.48 (8)	H1WA—O1W—H1WB	103.5
P1—O11—K1^iv	148.17 (8)	H2WA—O2W—H2WB	110.8

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O13—H13···O21^v	0.82	1.71	2.5124 (18)	165
O22—H22···O11^vi	0.82	1.73	2.526 (2)	164
O1—H1···O2W^vii	0.82	2.00	2.744 (2)	150
N2—H2···O12^viii	0.87	1.81	2.646 (2)	161
O1W—H1WA···O23^iii	0.82	2.00	2.783 (2)	159
O1W—H1WB···O12^vi	0.82	2.31	3.068 (2)	152
O1W—H1WB···O11^vi	0.82	2.39	3.039 (2)	136
O2W—H2WA···O12	0.82	2.00	2.817 (2)	173
O2W—H2WB···O23^ix	0.82	1.96	2.768 (2)	170
C5—H5···O23^v	0.93	2.36	3.274 (3)	166

Symmetry codes: (iii) −x+2, −y+2, −z; (v) x−1, y, z; (vi) −x+1, −y+1, −z; (vii) x+1, y, z; (viii) −x+1, −y+1, −z+1; (ix) x−1, y−1, z.