catena-Poly[[diaqua­copper(II)]-μ-7-oxa­bicyclo­[2.2.1]heptane-2,3-dicarboxyl­ato]

Wang, Y.-Y.; Hu, R.-D.; Wang, Y.-J.

doi:10.1107/S1600536809000270

metal-organic compounds

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ISSN: 2056-9890

Volume 65| Part 2| February 2009| Page m169

doi:10.1107/S1600536809000270

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catena-Poly[[diaquacopper(II)]-μ-7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylato]

Yun-Yun Wang,^a Rui-Ding Hu ^a ^* and Yan-Jun Wang ^a

^aZhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, People's Republic of China, and, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, Zhejiang, People's Republic of China
^*Correspondence e-mail: huruiding@zjnu.cn

(Received 18 December 2008; accepted 5 January 2009; online 10 January 2009)

In the crystal structure of the title compound, [Cu(C₈H₈O₅)(H₂O)₂]_n, the Cu(II) cation is in a Jahn–Teller distorted six-coordination by two O atoms from water molecules, by the bridging O atom from the bicyclo moiety, by two carboxylate O atoms from two different carboxylate groups and by one carboxylate O atom from a symmetry-related bridging ligand.The polymeric structure is made up from double-strands propagating parallel to the c axis that are held together via intermolecular O—H⋯O hydrogen bonds.

Related literature

For related literature, see: Yin et al. (2003 ).

Experimental

Crystal data

[Cu(C₈H₈O₅)(H₂O)₂]
M_r = 283.72
Orthorhombic, I b a 2
a = 10.5512 (4) Å
b = 19.3389 (9) Å
c = 9.7435 (4) Å
V = 1988.15 (14) Å³
Z = 8
Mo Kα radiation
μ = 2.22 mm⁻¹
T = 296 (2) K
0.29 × 0.20 × 0.12 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.60, T_max = 0.78
7372 measured reflections
2078 independent reflections
1897 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.022
wR(F²) = 0.059
S = 1.02
2078 reflections
157 parameters
9 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.38 e Å⁻³
Absolute structure: Flack (1983 ), 857 Friedel pairs
Flack parameter: 0.001 (16)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1WA⋯O1ⁱ	0.842 (17)	2.05 (2)	2.835 (3)	154 (4)
O1W—H1WB⋯O2ⁱⁱ	0.852 (17)	1.91 (2)	2.731 (2)	161 (3)
O2W—H2WA⋯O1ⁱⁱⁱ	0.871 (17)	2.001 (18)	2.870 (2)	175 (3)
O2W—H2WB⋯O1Wⁱ	0.795 (18)	2.21 (3)	2.920 (3)	148 (3)
O2W—H2WB⋯O4ⁱ	0.795 (18)	2.20 (3)	2.780 (3)	130 (3)
Symmetry codes: (i) $[x, -y, z-{\script{1\over 2}}]$ ; (ii) -x, -y, z; (iii) $[-x, y, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; 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: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809000270/at2697sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809000270/at2697Isup2.hkl

checkCIF report

Comment top

7-Oxabicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride (norcantharidin), a traditional Chinese drug, has great anti-cancer activity. It has been widely used as an anticancer drug to treat hepatoma, lung cancer, esophagus cancer and gastric cancer for a long time. Copper is an essential microelement in human body and it exists in the form of copper proteins in animal bodies. Copper coordination compounds have strong bioactivity and various structures, therefore people pay more attention to them and have synthesized some complexes that have pronounced anticancer activity, bactericidal activity, anti-proliferative effect in recent years (Yin et al., 2003). In order to prepare compounds with pronounced anti-cancer activity, we synthesized Cu^II complex of norcantharidin, whose anti-cancer activity test is being carried out.

In the title compound, each Cu^II ion is six-coordinated by two oxygen atoms from water, one bridge oxygen, two carboxylate oxygen atoms in two different carboxylate groups and one carboxylate oxygen atom in another asymmetric unit. O4, O5, O2W and O1W lie in the equatorial plane with the torsion angle -1.004 (62)°. Carboxylate oxygen atom O2 and O3 from another bridge ligand unit are in the axial positions. The bond angle of O2—Cu1—O3 is 171.256 (73)°, so it forms a distorted octahedral. Owing to the binding of the bridge oxygen atom with Cu, two six-membered rings (Cu1—O5—C4—C5—C8—O4 and Cu1—O2—C7—C6—C1—O5) are created. In addition, a seven-membered ring (Cu1—O4—C8—C5—C6—C7—O2) is formed because of the coordination of carboxylate oxygen atoms O2 and O4. What's more, intermolecular hydrogen bonds of the complex make the compound more stable.

Related literature top

For related literature, see: Yin et al. (2003).

Experimental top

A mixture of norcantharidin and CuCl_2.2H₂O was dissolved in 20 mL absolute ethyl alcohol and stirred for 4 h at room temperature and then refluxed for 2 h at 333 K. The blue solution was filtered and after 2 weeks block green single crystals were obtained.

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); 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: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. A view of the molecule of (I) showing the atom-labelling scheme with displacement ellipsoids drawn at the 30% probability.

catena-Poly[[diaquacopper(II)]-µ-7-oxabicyclo[2.2.1]heptane-2,3- dicarboxylato] top

Crystal data top

[Cu(C₈H₈O₅)(H₂O)₂]	F(000) = 1160
M_r = 283.72	D_x = 1.896 Mg m⁻³
Orthorhombic, Iba2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: I 2 -2c	Cell parameters from 4186 reflections
a = 10.5512 (4) Å	θ = 2.1–27.5°
b = 19.3389 (9) Å	µ = 2.22 mm⁻¹
c = 9.7435 (4) Å	T = 296 K
V = 1988.15 (14) Å³	Block, green
Z = 8	0.29 × 0.20 × 0.12 mm

Data collection top

Bruker APEXII area-detector diffractometer	2078 independent reflections
Radiation source: fine-focus sealed tube	1897 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
ω scans	θ_max = 27.5°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −13→13
T_min = 0.60, T_max = 0.78	k = −21→25
7372 measured reflections	l = −10→12

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.022	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.059	w = 1/[σ²(F_o²) + (0.0368P)²] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max < 0.001
2078 reflections	Δρ_max = 0.32 e Å⁻³
157 parameters	Δρ_min = −0.38 e Å⁻³
9 restraints	Absolute structure: Flack (1983), 857 Freidel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.001 (16)

Crystal data top

[Cu(C₈H₈O₅)(H₂O)₂]	V = 1988.15 (14) Å³
M_r = 283.72	Z = 8
Orthorhombic, Iba2	Mo Kα radiation
a = 10.5512 (4) Å	µ = 2.22 mm⁻¹
b = 19.3389 (9) Å	T = 296 K
c = 9.7435 (4) Å	0.29 × 0.20 × 0.12 mm

Data collection top

Bruker APEXII area-detector diffractometer	2078 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1897 reflections with I > 2σ(I)
T_min = 0.60, T_max = 0.78	R_int = 0.021
7372 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.022	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.059	Δρ_max = 0.32 e Å⁻³
S = 1.02	Δρ_min = −0.38 e Å⁻³
2078 reflections	Absolute structure: Flack (1983), 857 Freidel pairs
157 parameters	Absolute structure parameter: 0.001 (16)
9 restraints

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
Cu1	0.243032 (19)	0.040771 (14)	0.45597 (9)	0.02570 (9)
O1	0.08219 (15)	0.14342 (9)	0.76589 (19)	0.0351 (4)
O1W	0.11498 (18)	−0.05770 (11)	0.4992 (2)	0.0476 (6)
H1WA	0.117 (3)	−0.0923 (14)	0.447 (3)	0.071*
H1WB	0.044 (2)	−0.0648 (17)	0.538 (3)	0.071*
O2	0.12635 (15)	0.09609 (10)	0.5661 (2)	0.0367 (5)
O2W	0.16510 (19)	0.08276 (13)	0.2897 (2)	0.0471 (6)
H2WA	0.092 (2)	0.1034 (16)	0.283 (4)	0.071*
H2WB	0.170 (3)	0.0631 (18)	0.218 (3)	0.071*
O3	0.34512 (15)	0.02601 (8)	0.85851 (18)	0.0285 (4)
O4	0.31828 (14)	0.00547 (9)	0.63735 (17)	0.0287 (4)
O5	0.38661 (12)	0.13101 (8)	0.4694 (2)	0.0278 (3)
C1	0.3288 (2)	0.19244 (12)	0.5275 (3)	0.0324 (6)
H1A	0.2597	0.2112	0.4717	0.039*
C2	0.4418 (3)	0.24140 (14)	0.5415 (3)	0.0458 (7)
H2A	0.4284	0.2749	0.6142	0.055*
H2B	0.4588	0.2655	0.4562	0.055*
C3	0.5491 (2)	0.19062 (15)	0.5777 (3)	0.0421 (7)
H3A	0.6159	0.1915	0.5092	0.051*
H3B	0.5851	0.2007	0.6671	0.051*
C4	0.4799 (2)	0.12166 (13)	0.5777 (3)	0.0284 (5)
H4A	0.5357	0.0818	0.5635	0.034*
C5	0.39748 (19)	0.11620 (12)	0.7068 (2)	0.0242 (5)
H5A	0.4444	0.1336	0.7865	0.029*
C6	0.2864 (2)	0.16753 (12)	0.6698 (3)	0.0269 (5)
H6A	0.2863	0.2065	0.7343	0.032*
C7	0.1552 (2)	0.13317 (12)	0.6683 (3)	0.0268 (5)
C8	0.35037 (18)	0.04365 (11)	0.7353 (3)	0.0221 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.02380 (12)	0.03211 (16)	0.02120 (16)	0.00285 (9)	−0.00032 (15)	−0.00532 (16)
O1	0.0333 (8)	0.0431 (10)	0.0290 (10)	0.0053 (8)	0.0067 (8)	−0.0028 (8)
O1W	0.0330 (9)	0.0613 (12)	0.0486 (16)	−0.0163 (8)	0.0057 (8)	−0.0157 (10)
O2	0.0241 (8)	0.0512 (11)	0.0347 (13)	0.0028 (8)	0.0018 (7)	−0.0157 (10)
O2W	0.0439 (10)	0.0700 (16)	0.0276 (12)	0.0251 (10)	−0.0055 (9)	−0.0087 (10)
O3	0.0294 (8)	0.0350 (9)	0.0210 (10)	−0.0072 (7)	−0.0016 (7)	0.0082 (8)
O4	0.0346 (8)	0.0295 (9)	0.0222 (9)	−0.0048 (7)	0.0009 (6)	−0.0027 (7)
O5	0.0289 (6)	0.0320 (8)	0.0226 (9)	−0.0002 (6)	0.0016 (7)	0.0006 (8)
C1	0.0382 (13)	0.0283 (12)	0.0307 (16)	0.0052 (10)	−0.0037 (11)	0.0056 (12)
C2	0.0594 (19)	0.0329 (15)	0.0451 (19)	−0.0131 (12)	0.0053 (14)	0.0066 (14)
C3	0.0381 (14)	0.0525 (17)	0.0358 (18)	−0.0196 (12)	0.0025 (12)	0.0060 (13)
C4	0.0240 (10)	0.0346 (13)	0.0267 (14)	−0.0013 (9)	0.0013 (9)	0.0051 (11)
C5	0.0227 (9)	0.0287 (13)	0.0211 (13)	−0.0014 (9)	−0.0027 (8)	0.0002 (10)
C6	0.0322 (10)	0.0243 (12)	0.0242 (13)	0.0040 (9)	0.0004 (10)	−0.0038 (11)
C7	0.0254 (10)	0.0273 (12)	0.0277 (14)	0.0076 (9)	−0.0022 (10)	0.0022 (11)
C8	0.0134 (8)	0.0285 (12)	0.0245 (14)	0.0024 (8)	0.0014 (8)	0.0003 (10)

Geometric parameters (Å, º) top

Cu1—O3ⁱ	1.9313 (16)	C1—C2	1.528 (4)
Cu1—O2	1.9524 (17)	C1—C6	1.535 (4)
Cu1—O2W	1.990 (2)	C1—H1A	0.9800
Cu1—O4	2.0542 (19)	C2—C3	1.540 (4)
Cu1—O5	2.3147 (14)	C2—H2A	0.9700
Cu1—O1W	2.3726 (19)	C2—H2B	0.9700
O1—C7	1.240 (3)	C3—C4	1.521 (3)
O1W—H1WA	0.842 (17)	C3—H3A	0.9700
O1W—H1WB	0.852 (17)	C3—H3B	0.9700
O2—C7	1.264 (3)	C4—C5	1.533 (3)
O2W—H2WA	0.871 (17)	C4—H4A	0.9800
O2W—H2WB	0.795 (18)	C5—C8	1.514 (3)
O3—C8	1.249 (3)	C5—C6	1.578 (3)
O3—Cu1ⁱⁱ	1.9313 (16)	C5—H5A	0.9800
O4—C8	1.253 (3)	C6—C7	1.536 (3)
O5—C1	1.450 (3)	C6—H6A	0.9800
O5—C4	1.454 (3)

O3ⁱ—Cu1—O2	171.25 (8)	C3—C2—H2A	111.5
O3ⁱ—Cu1—O2W	95.92 (9)	C1—C2—H2B	111.5
O2—Cu1—O2W	87.90 (8)	C3—C2—H2B	111.5
O3ⁱ—Cu1—O4	89.15 (7)	H2A—C2—H2B	109.3
O2—Cu1—O4	87.30 (8)	C4—C3—C2	101.87 (19)
O2W—Cu1—O4	174.69 (8)	C4—C3—H3A	111.4
O3ⁱ—Cu1—O5	99.62 (6)	C2—C3—H3A	111.4
O2—Cu1—O5	88.19 (7)	C4—C3—H3B	111.4
O2W—Cu1—O5	90.51 (9)	C2—C3—H3B	111.4
O4—Cu1—O5	87.07 (6)	H3A—C3—H3B	109.3
O3ⁱ—Cu1—O1W	82.43 (8)	O5—C4—C3	102.49 (19)
O2—Cu1—O1W	89.03 (8)	O5—C4—C5	102.70 (16)
O2W—Cu1—O1W	103.70 (9)	C3—C4—C5	109.4 (2)
O4—Cu1—O1W	78.49 (7)	O5—C4—H4A	113.7
O5—Cu1—O1W	165.41 (8)	C3—C4—H4A	113.7
Cu1—O1W—H1WA	121 (2)	C5—C4—H4A	113.7
Cu1—O1W—H1WB	135 (2)	C8—C5—C4	113.6 (2)
H1WA—O1W—H1WB	99 (2)	C8—C5—C6	112.40 (17)
C7—O2—Cu1	126.29 (15)	C4—C5—C6	100.98 (19)
Cu1—O2W—H2WA	128 (3)	C8—C5—H5A	109.9
Cu1—O2W—H2WB	120 (3)	C4—C5—H5A	109.9
H2WA—O2W—H2WB	102 (2)	C6—C5—H5A	109.9
C8—O3—Cu1ⁱⁱ	132.82 (15)	C1—C6—C7	112.9 (2)
C8—O4—Cu1	124.31 (15)	C1—C6—C5	100.79 (19)
C1—O5—C4	95.93 (17)	C7—C6—C5	113.56 (18)
C1—O5—Cu1	111.39 (12)	C1—C6—H6A	109.7
C4—O5—Cu1	112.98 (13)	C7—C6—H6A	109.7
O5—C1—C2	102.40 (19)	C5—C6—H6A	109.7
O5—C1—C6	102.60 (18)	O1—C7—O2	123.0 (2)
C2—C1—C6	110.0 (2)	O1—C7—C6	118.9 (2)
O5—C1—H1A	113.6	O2—C7—C6	118.1 (2)
C2—C1—H1A	113.6	O3—C8—O4	124.0 (2)
C6—C1—H1A	113.6	O3—C8—C5	116.3 (2)
C1—C2—C3	101.5 (2)	O4—C8—C5	119.7 (2)
C1—C2—H2A	111.5

O2W—Cu1—O2—C7	−131.2 (2)	C2—C3—C4—O5	34.5 (2)
O4—Cu1—O2—C7	46.5 (2)	C2—C3—C4—C5	−74.0 (3)
O5—Cu1—O2—C7	−40.6 (2)	O5—C4—C5—C8	86.0 (2)
O1W—Cu1—O2—C7	125.0 (2)	C3—C4—C5—C8	−165.65 (19)
O3ⁱ—Cu1—O4—C8	139.29 (16)	O5—C4—C5—C6	−34.5 (2)
O2—Cu1—O4—C8	−48.70 (17)	C3—C4—C5—C6	73.8 (2)
O5—Cu1—O4—C8	39.62 (16)	O5—C1—C6—C7	−85.9 (2)
O1W—Cu1—O4—C8	−138.26 (17)	C2—C1—C6—C7	165.7 (2)
O3ⁱ—Cu1—O5—C1	174.10 (15)	O5—C1—C6—C5	35.6 (2)
O2—Cu1—O5—C1	−9.87 (16)	C2—C1—C6—C5	−72.8 (2)
O2W—Cu1—O5—C1	78.01 (16)	C8—C5—C6—C1	−122.0 (2)
O4—Cu1—O5—C1	−97.26 (16)	C4—C5—C6—C1	−0.6 (2)
O1W—Cu1—O5—C1	−89.0 (3)	C8—C5—C6—C7	−0.9 (3)
O3ⁱ—Cu1—O5—C4	−79.25 (15)	C4—C5—C6—C7	120.5 (2)
O2—Cu1—O5—C4	96.78 (15)	Cu1—O2—C7—O1	−148.85 (19)
O2W—Cu1—O5—C4	−175.34 (15)	Cu1—O2—C7—C6	31.8 (3)
O4—Cu1—O5—C4	9.39 (14)	C1—C6—C7—O1	−142.1 (2)
O1W—Cu1—O5—C4	17.7 (3)	C5—C6—C7—O1	104.0 (3)
C4—O5—C1—C2	56.4 (2)	C1—C6—C7—O2	37.3 (3)
Cu1—O5—C1—C2	173.91 (15)	C5—C6—C7—O2	−76.7 (3)
C4—O5—C1—C6	−57.6 (2)	Cu1ⁱⁱ—O3—C8—O4	−25.2 (3)
Cu1—O5—C1—C6	59.9 (2)	Cu1ⁱⁱ—O3—C8—C5	154.10 (15)
O5—C1—C2—C3	−34.9 (3)	Cu1—O4—C8—O3	148.71 (18)
C6—C1—C2—C3	73.6 (3)	Cu1—O4—C8—C5	−30.6 (2)
C1—C2—C3—C4	0.2 (3)	C4—C5—C8—O3	142.9 (2)
C1—O5—C4—C3	−56.3 (2)	C6—C5—C8—O3	−103.2 (2)
Cu1—O5—C4—C3	−172.55 (15)	C4—C5—C8—O4	−37.8 (3)
C1—O5—C4—C5	57.25 (19)	C6—C5—C8—O4	76.1 (3)
Cu1—O5—C4—C5	−59.00 (19)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1ⁱ	0.84 (2)	2.05 (2)	2.835 (3)	154 (4)
O1W—H1WB···O2ⁱⁱⁱ	0.85 (2)	1.91 (2)	2.731 (2)	161 (3)
O2W—H2WA···O1^iv	0.87 (2)	2.00 (2)	2.870 (2)	175 (3)
O2W—H2WB···O1Wⁱ	0.80 (2)	2.21 (3)	2.920 (3)	148 (3)
O2W—H2WB···O4ⁱ	0.80 (2)	2.20 (3)	2.780 (3)	130 (3)

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

Experimental details

Crystal data
Chemical formula	[Cu(C₈H₈O₅)(H₂O)₂]
M_r	283.72
Crystal system, space group	Orthorhombic, Iba2
Temperature (K)	296
a, b, c (Å)	10.5512 (4), 19.3389 (9), 9.7435 (4)
V (Å³)	1988.15 (14)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	2.22
Crystal size (mm)	0.29 × 0.20 × 0.12

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.60, 0.78
No. of measured, independent and observed [I > 2σ(I)] reflections	7372, 2078, 1897
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.022, 0.059, 1.02
No. of reflections	2078
No. of parameters	157
No. of restraints	9
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.38
Absolute structure	Flack (1983), 857 Freidel pairs
Absolute structure parameter	0.001 (16)

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1ⁱ	0.842 (17)	2.05 (2)	2.835 (3)	154 (4)
O1W—H1WB···O2ⁱⁱ	0.852 (17)	1.91 (2)	2.731 (2)	161 (3)
O2W—H2WA···O1ⁱⁱⁱ	0.871 (17)	2.001 (18)	2.870 (2)	175 (3)
O2W—H2WB···O1Wⁱ	0.795 (18)	2.21 (3)	2.920 (3)	148 (3)
O2W—H2WB···O4ⁱ	0.795 (18)	2.20 (3)	2.780 (3)	130 (3)

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

Acknowledgements

The authors acknowledge financial support from the Natural Science Foundation of Zhejiang Province, China (grant No. Y407301).

References

Bruker (2004). SAINT and APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yin, F.-L., Shen, J., Zou, J.-J. & Li, R.-C. (2003). Acta Chim. Sin. 61, 556–561. CAS Google Scholar

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