1-(5-Chloro-2,4-dihydroxy­phen­yl)-2-(4-ethoxy­phen­yl)ethanone

Botting, N.P.; Slawin, A.M.Z.; Zhang, Q.

doi:10.1107/S1600536808030699

organic compounds

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ISSN: 2056-9890

Volume 64| Part 10| October 2008| Page o2030

doi:10.1107/S1600536808030699

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1-(5-Chloro-2,4-dihydroxyphenyl)-2-(4-ethoxyphenyl)ethanone

Nigel P. Botting,^a Alexandra M. Z. Slawin ^a ^* and Qingzhi Zhang ^a

^aDepartment of Chemistry, University of St Andrews, St Andrews KY16 9ST, Scotland
^*Correspondence e-mail: amzs@st-and.ac.uk

(Received 5 September 2008; accepted 23 September 2008; online 27 September 2008)

The structure of the title compound, C₁₆H₁₅ClO₄, contains aryl rings which are inclined by 75.6 (1)° to each other. It displays intramolecular O—H⋯O hydrogen bonding between the 2-hydroxy and carbonyl groups, forming a six-membered ring. Furthermore, the 4-hydroxy group, acting as a hydrogen-bond donor, is bound to the O atom of the 2-hydroxy group of another molecule.

Related literature

For related literature, see: Anderson & Garner (1997 ); Fokialakis et al. (2004 ); Papoutsi et al. (2007 ); Anthony (2002 ); Barnes (1998 ); Barnes & Peterson (1995 ); Dixon & Ferreira (2002 ); Greenwood et al. (2000 ); Setchell (1998 ); Whalley et al. (2000 ). For a related structure, see: Arumugan et al. (2007 ).

Experimental

Crystal data

C₁₆H₁₅ClO₄
M_r = 306.73
Monoclinic, I 2/a
a = 19.255 (6) Å
b = 4.6454 (15) Å
c = 31.109 (11) Å
β = 90.519 (7)°
V = 2782.5 (16) Å³
Z = 8
Mo Kα radiation
μ = 0.29 mm⁻¹
T = 125 (2) K
0.11 × 0.03 × 0.03 mm

Data collection

Bruker SMART diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.983, T_max = 0.997
8448 measured reflections
2515 independent reflections
1401 reflections with I > 2σ(I)
R_int = 0.091

Refinement

R[F² > 2σ(F²)] = 0.049
wR(F²) = 0.101
S = 0.89
2515 reflections
199 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2O⋯O7	0.98 (1)	1.71 (3)	2.542 (3)	141 (3)
O4—H4O⋯O2ⁱ	0.98 (1)	1.821 (9)	2.784 (3)	167 (3)
Symmetry code: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: SMART (Bruker, 2001); cell refinement: SMART; data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808030699/wn2279sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808030699/wn2279Isup2.hkl

checkCIF report

Comment top

Phytoestrogens, in particular the soy isoflavones such as daidzein and genistein, have positive impact on human health (Setchell, 1998; Barnes, 1998 and Dixon & Ferreira, 2002). High consumption of soy products has been associated with a low incidence of hormone-dependent cancers (Barnes & Peterson, 1995), the symptom alleviation of menopause (Greenwood et al., 2000) and protection against osteoporosis (Anderson & Garner, 1997) as well as cardiovascular disease (Anthony, 2002). Consequently, there is growing interest in using phytoestrogens and synthetic derivatives for the chemoprevention and therapy of these diseases.

One of the synthetic routes to daidzein and its derivatives is via the Freidel-Crafts reaction of resorcinol and phenylacetic acid catalysed by boron trifluoride etherate (Whalley, et al., 2000), giving the deoxybenzoin intermediate. In the preparation of 5-chlorodaidzein, 1-(5-chloro-2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone (2) was obtained (yield 77%) from the coupling of 5-cholororesorcinol with 4-hydroxyphenylacetic acid in boron trifluoride etherate. Surprisingly, the title compound, 1-(5-chloro-2,4-dihydroxyphenyl)-2-(4-ethoxyphenyl)-ethanone (1), was also isolated in small amount (5% yield). Boron trifluoride proves to be such a strong Lewis acid, it not only catalyses the Freidel-Crafts reaction, but also activates the diethyl ether and makes it an electrophile. From the position of ethylation, it can be concluded that (1) is formed from the attack of (2) via 4-hydroxyphenyl to the α-position of the actived diethyl ether, because the 4-OH of the benzyl ring is more nucleophilic than the 2-OH and the 4-OH in the other phenyl ring which bears the electron-withdrawing carbonyl group. (1) has been previously synthesized as the major product from 5-chlororesorcinol and 4-ethoxyphenylacetic acid (Fokialakis et al. 2004). The deoxybenzoin shows some estrogenic activity like daidzein (Fokialakis et al., 2004; Papoutsi et al., 2007).

The molecular structure of (1) is conformationally similar to that of deoxyanisoin, MeOC₆H₄C(O)CH₂C₆H₄OMe. (Arumugan et al. 2007) with statistically invariant C═O and C—C bond lengths and very similar backbone torsion angles, though C4—O4 in 1 appears to be marginally shorter at 1.347 (3) Å than in deoxyanisoin at 1.378 (1) Å; this may be a consequence of the neighbouring chloro substituent in (1).

Related literature top

For related literature, see: Anderson & Garner (1997); Fokialakis et al. (2004); Papoutsi et al. (2007); Anthony (2002); Barnes (1998); Barnes & Peterson (1995); Dixon & Ferreira (2002); Greenwood et al. (2000); Setchell (1998); Whalley et al. (2000); Arumugan et al. (2007).

Experimental top

Boron trifluoride diethyl etherate (7.7 ml, 60.7 mmol) was added to a mixture of resorcinol (4.4 g, 30.4 mmol) and 3-chloro-4-hydroxyphenylacetic acid (4.63 g, 30.4 mmol) under a nitrogen atmosphere. The mixture was heated to reflux for 5 h, cooled to room temperature, and saturated aqueous sodium acetate (50 ml) and aqueous sodium hydrogen carbonate (40 ml) added sequentially. The mixture was extracted with diethyl ether (3 × 50 ml), dried MgSO₄ and the solvent removed at reduced pressure.Column chromatography on silica, with hexane/ethyl acetate (1:1) as eluant, gave the title compound (1) (0.47 g, 5%). ¹H NMR and ¹³C NMR (CDCl₃) of (1) as well as MS were in agreement with that in the literature (Fokialakis et al., 2004).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. Carbon-bound H atoms have been omitted; H atoms bonded to oxygen are represented as spheres of arbitrary radius.
	Fig. 2. A packing diagram, with hydrogen bonding interactions indicated as dashed lines. Hydrogen atoms not involved in hydrogen bonding have been omitted.

1-(5-Chloro-2,4-dihydroxyphenyl)-2-(4-ethoxyphenyl)ethanone top

Crystal data top

C₁₆H₁₅ClO₄	F(000) = 1280
M_r = 306.73	D_x = 1.464 Mg m⁻³
Monoclinic, I2/a	Mo Kα radiation, λ = 0.71073 Å
a = 19.255 (6) Å	Cell parameters from 306 reflections
b = 4.6454 (15) Å	θ = 12–28°
c = 31.109 (11) Å	µ = 0.29 mm⁻¹
β = 90.519 (7)°	T = 125 K
V = 2782.5 (16) Å³	Prism, colourless
Z = 8	0.11 × 0.03 × 0.03 mm

Data collection top

Bruker SMART diffractometer	2515 independent reflections
Radiation source: fine-focus sealed tube	1401 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.091
Detector resolution: 0.83 pixels mm^-1	θ_max = 25.4°, θ_min = 2.1°
ϕ and ω scans	h = −22→23
Absorption correction: multi-scan (SADABS; Bruker, 2001)	k = −5→5
T_min = 0.983, T_max = 0.997	l = −37→31
8448 measured reflections

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.101	H atoms treated by a mixture of independent and constrained refinement
S = 0.89	w = 1/[σ²(F_o²) + (0.0438P)²] where P = (F_o² + 2F_c²)/3
2515 reflections	(Δ/σ)_max = 0.033
199 parameters	Δρ_max = 0.28 e Å⁻³
2 restraints	Δρ_min = −0.27 e Å⁻³

Crystal data top

C₁₆H₁₅ClO₄	V = 2782.5 (16) Å³
M_r = 306.73	Z = 8
Monoclinic, I2/a	Mo Kα radiation
a = 19.255 (6) Å	µ = 0.29 mm⁻¹
b = 4.6454 (15) Å	T = 125 K
c = 31.109 (11) Å	0.11 × 0.03 × 0.03 mm
β = 90.519 (7)°

Data collection top

Bruker SMART diffractometer	2515 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	1401 reflections with I > 2σ(I)
T_min = 0.983, T_max = 0.997	R_int = 0.091
8448 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.049	2 restraints
wR(F²) = 0.101	H atoms treated by a mixture of independent and constrained refinement
S = 0.89	Δρ_max = 0.28 e Å⁻³
2515 reflections	Δρ_min = −0.27 e Å⁻³
199 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
C1	0.33978 (15)	0.7593 (6)	0.18759 (10)	0.0179 (7)
C2	0.39148 (16)	0.8676 (6)	0.21571 (10)	0.0178 (8)
O2	0.37615 (11)	1.0672 (4)	0.24646 (7)	0.0217 (5)
H2O	0.3277 (6)	1.130 (8)	0.2439 (13)	0.076 (14)*
C3	0.45909 (15)	0.7723 (6)	0.21336 (10)	0.0189 (7)
H3A	0.4931	0.8474	0.2326	0.023*
C4	0.47810 (16)	0.5683 (6)	0.18323 (10)	0.0193 (8)
O4	0.54308 (11)	0.4628 (5)	0.18053 (7)	0.0258 (6)
H4O	0.5655 (16)	0.516 (8)	0.2078 (6)	0.064 (13)*
C5	0.42808 (16)	0.4638 (6)	0.15414 (10)	0.0195 (8)
Cl5	0.45154 (4)	0.21806 (16)	0.11487 (3)	0.0265 (3)
C6	0.36084 (16)	0.5567 (6)	0.15684 (10)	0.0192 (8)
H6A	0.3273	0.4817	0.1373	0.023*
C7	0.26827 (16)	0.8586 (6)	0.19047 (10)	0.0193 (8)
O7	0.25248 (11)	1.0457 (5)	0.21737 (7)	0.0295 (6)
C8	0.21213 (15)	0.7476 (6)	0.16079 (10)	0.0234 (8)
H8A	0.2267	0.5604	0.1486	0.028*
H8B	0.1692	0.7156	0.1774	0.028*
C9	0.19729 (16)	0.9550 (6)	0.12476 (10)	0.0187 (8)
C10	0.24738 (17)	1.0299 (7)	0.09503 (11)	0.0258 (8)
H10A	0.2925	0.9486	0.0974	0.031*
C11	0.23309 (16)	1.2204 (7)	0.06193 (10)	0.0270 (8)
H11A	0.2681	1.2687	0.0419	0.032*
C12	0.16775 (17)	1.3401 (7)	0.05814 (11)	0.0239 (8)
C13	0.11677 (16)	1.2740 (6)	0.08744 (10)	0.0234 (8)
H13A	0.0719	1.3582	0.0851	0.028*
C14	0.13229 (16)	1.0809 (6)	0.12065 (10)	0.0222 (8)
H14A	0.0974	1.0349	0.1409	0.027*
O12	0.15829 (10)	1.5204 (5)	0.02307 (7)	0.0293 (6)
C15	0.09030 (16)	1.6385 (7)	0.01654 (11)	0.0271 (9)
H15A	0.0773	1.7614	0.0412	0.033*
H15B	0.0556	1.4824	0.0136	0.033*
C16	0.09290 (17)	1.8138 (7)	−0.02397 (11)	0.0336 (9)
H16A	0.0472	1.8999	−0.0296	0.050*
H16B	0.1055	1.6894	−0.0481	0.050*
H16C	0.1276	1.9667	−0.0207	0.050*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0173 (17)	0.0189 (17)	0.0175 (18)	−0.0018 (14)	−0.0035 (14)	0.0016 (14)
C2	0.0209 (19)	0.0137 (16)	0.019 (2)	−0.0004 (14)	−0.0014 (15)	0.0023 (13)
O2	0.0231 (13)	0.0224 (12)	0.0195 (13)	0.0028 (10)	−0.0057 (11)	−0.0029 (10)
C3	0.0188 (17)	0.0197 (17)	0.0181 (18)	−0.0015 (15)	−0.0058 (14)	0.0000 (15)
C4	0.0155 (17)	0.0210 (18)	0.021 (2)	0.0020 (15)	−0.0025 (15)	0.0071 (15)
O4	0.0217 (13)	0.0300 (14)	0.0257 (15)	0.0023 (11)	−0.0048 (11)	−0.0025 (11)
C5	0.0269 (19)	0.0146 (17)	0.0170 (19)	−0.0009 (15)	−0.0009 (16)	0.0008 (14)
Cl5	0.0277 (5)	0.0265 (5)	0.0250 (5)	0.0027 (4)	−0.0029 (4)	−0.0061 (4)
C6	0.0208 (18)	0.0156 (17)	0.021 (2)	0.0002 (14)	−0.0031 (15)	−0.0006 (14)
C7	0.0247 (19)	0.0157 (17)	0.017 (2)	−0.0003 (14)	−0.0004 (16)	0.0028 (14)
O7	0.0270 (13)	0.0342 (14)	0.0273 (15)	0.0057 (11)	−0.0066 (11)	−0.0070 (11)
C8	0.0191 (17)	0.0207 (18)	0.030 (2)	−0.0013 (15)	−0.0065 (15)	0.0011 (16)
C9	0.0183 (18)	0.0181 (18)	0.020 (2)	−0.0014 (15)	−0.0037 (16)	−0.0024 (14)
C10	0.0191 (18)	0.031 (2)	0.028 (2)	0.0033 (16)	−0.0058 (17)	−0.0016 (17)
C11	0.0193 (18)	0.038 (2)	0.024 (2)	−0.0013 (17)	0.0011 (15)	−0.0004 (17)
C12	0.029 (2)	0.0213 (18)	0.021 (2)	−0.0015 (15)	−0.0079 (17)	−0.0006 (15)
C13	0.0203 (17)	0.0201 (18)	0.030 (2)	0.0024 (15)	−0.0057 (16)	−0.0024 (16)
C14	0.0222 (19)	0.0230 (18)	0.021 (2)	−0.0043 (15)	0.0019 (16)	−0.0006 (15)
O12	0.0236 (13)	0.0358 (14)	0.0285 (15)	0.0003 (11)	−0.0052 (11)	0.0087 (11)
C15	0.0272 (19)	0.0232 (18)	0.031 (2)	0.0013 (15)	−0.0077 (17)	0.0063 (15)
C16	0.035 (2)	0.035 (2)	0.031 (2)	0.0023 (18)	−0.0047 (18)	0.0049 (17)

Geometric parameters (Å, º) top

C1—C6	1.404 (4)	C9—C14	1.386 (4)
C1—C2	1.412 (4)	C9—C10	1.387 (4)
C1—C7	1.456 (4)	C10—C11	1.384 (4)
C2—O2	1.366 (4)	C10—H10A	0.9500
C2—C3	1.378 (4)	C11—C12	1.380 (4)
O2—H2O	0.9799 (11)	C11—H11A	0.9500
C3—C4	1.385 (4)	C12—C13	1.380 (5)
C3—H3A	0.9500	C12—O12	1.386 (4)
C4—O4	1.347 (3)	C13—C14	1.398 (4)
C4—C5	1.402 (4)	C13—H13A	0.9500
O4—H4O	0.9800 (11)	C14—H14A	0.9500
C5—C6	1.368 (4)	O12—C15	1.432 (4)
C5—Cl5	1.735 (3)	C15—C16	1.502 (4)
C6—H6A	0.9500	C15—H15A	0.9900
C7—O7	1.246 (4)	C15—H15B	0.9900
C7—C8	1.506 (4)	C16—H16A	0.9800
C8—C9	1.504 (4)	C16—H16B	0.9800
C8—H8A	0.9900	C16—H16C	0.9800
C8—H8B	0.9900

C6—C1—C2	117.0 (3)	C14—C9—C8	120.3 (3)
C6—C1—C7	122.2 (3)	C10—C9—C8	122.0 (3)
C2—C1—C7	120.7 (3)	C11—C10—C9	121.5 (3)
O2—C2—C3	117.7 (3)	C11—C10—H10A	119.3
O2—C2—C1	121.3 (3)	C9—C10—H10A	119.3
C3—C2—C1	120.9 (3)	C12—C11—C10	119.8 (3)
C2—O2—H2O	111 (2)	C12—C11—H11A	120.1
C2—C3—C4	120.8 (3)	C10—C11—H11A	120.1
C2—C3—H3A	119.6	C11—C12—C13	120.5 (3)
C4—C3—H3A	119.6	C11—C12—O12	115.1 (3)
O4—C4—C3	122.8 (3)	C13—C12—O12	124.4 (3)
O4—C4—C5	117.8 (3)	C12—C13—C14	118.8 (3)
C3—C4—C5	119.3 (3)	C12—C13—H13A	120.6
C4—O4—H4O	105 (2)	C14—C13—H13A	120.6
C6—C5—C4	119.7 (3)	C9—C14—C13	121.7 (3)
C6—C5—Cl5	120.2 (2)	C9—C14—H14A	119.1
C4—C5—Cl5	120.0 (2)	C13—C14—H14A	119.1
C5—C6—C1	122.2 (3)	C12—O12—C15	117.2 (3)
C5—C6—H6A	118.9	O12—C15—C16	106.8 (3)
C1—C6—H6A	118.9	O12—C15—H15A	110.4
O7—C7—C1	119.9 (3)	C16—C15—H15A	110.4
O7—C7—C8	118.2 (3)	O12—C15—H15B	110.4
C1—C7—C8	121.9 (3)	C16—C15—H15B	110.4
C9—C8—C7	111.6 (2)	H15A—C15—H15B	108.6
C9—C8—H8A	109.3	C15—C16—H16A	109.5
C7—C8—H8A	109.3	C15—C16—H16B	109.5
C9—C8—H8B	109.3	H16A—C16—H16B	109.5
C7—C8—H8B	109.3	C15—C16—H16C	109.5
H8A—C8—H8B	108.0	H16A—C16—H16C	109.5
C14—C9—C10	117.7 (3)	H16B—C16—H16C	109.5

C6—C1—C2—O2	179.5 (3)	C2—C1—C7—C8	179.8 (3)
C7—C1—C2—O2	0.3 (4)	O7—C7—C8—C9	78.3 (4)
C6—C1—C2—C3	−1.4 (4)	C1—C7—C8—C9	−100.0 (3)
C7—C1—C2—C3	179.4 (3)	C7—C8—C9—C14	−117.3 (3)
O2—C2—C3—C4	179.4 (3)	C7—C8—C9—C10	61.9 (4)
C1—C2—C3—C4	0.2 (5)	C14—C9—C10—C11	−0.9 (5)
C2—C3—C4—O4	−178.1 (3)	C8—C9—C10—C11	179.8 (3)
C2—C3—C4—C5	1.6 (5)	C9—C10—C11—C12	0.1 (5)
O4—C4—C5—C6	177.4 (3)	C10—C11—C12—C13	0.8 (5)
C3—C4—C5—C6	−2.3 (5)	C10—C11—C12—O12	−177.9 (3)
O4—C4—C5—Cl5	−2.6 (4)	C11—C12—C13—C14	−0.8 (5)
C3—C4—C5—Cl5	177.6 (2)	O12—C12—C13—C14	177.8 (3)
C4—C5—C6—C1	1.1 (5)	C10—C9—C14—C13	0.9 (5)
Cl5—C5—C6—C1	−178.8 (2)	C8—C9—C14—C13	−179.8 (3)
C2—C1—C6—C5	0.7 (5)	C12—C13—C14—C9	−0.1 (5)
C7—C1—C6—C5	179.9 (3)	C11—C12—O12—C15	176.9 (3)
C6—C1—C7—O7	−177.6 (3)	C13—C12—O12—C15	−1.7 (4)
C2—C1—C7—O7	1.5 (4)	C12—O12—C15—C16	−177.7 (3)
C6—C1—C7—C8	0.6 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O7	0.98 (1)	1.71 (3)	2.542 (3)	141 (3)
O4—H4O···O2ⁱ	0.98 (1)	1.82 (1)	2.784 (3)	167 (3)

Symmetry code: (i) −x+1, y−1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₁₆H₁₅ClO₄
M_r	306.73
Crystal system, space group	Monoclinic, I2/a
Temperature (K)	125
a, b, c (Å)	19.255 (6), 4.6454 (15), 31.109 (11)
β (°)	90.519 (7)
V (Å³)	2782.5 (16)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.29
Crystal size (mm)	0.11 × 0.03 × 0.03

Data collection
Diffractometer	Bruker SMART diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2001)
T_min, T_max	0.983, 0.997
No. of measured, independent and observed [I > 2σ(I)] reflections	8448, 2515, 1401
R_int	0.091
(sin θ/λ)_max (Å⁻¹)	0.604

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.101, 0.89
No. of reflections	2515
No. of parameters	199
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.27

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O7	0.98 (1)	1.71 (3)	2.542 (3)	141 (3)
O4—H4O···O2ⁱ	0.98 (1)	1.821 (9)	2.784 (3)	167 (3)

Symmetry code: (i) −x+1, y−1/2, −z+1/2.

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Volume 64| Part 10| October 2008| Page o2030

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