Poly[diaqua­di-μ4-citrato-trizinc(II)]

Wu, J.

doi:10.1107/S1600536808007642

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 4| April 2008| Pages m583-m584

doi:10.1107/S1600536808007642

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Poly[diaquadi-μ₄-citrato-trizinc(II)]

Jian Wu ^a ^*

^aCollege of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006, Guangxi, People's Republic of China
^*Correspondence e-mail: wujian2007gx@126.com

(Received 8 March 2008; accepted 20 March 2008; online 29 March 2008)

The title compound, [Zn₃(C₆H₅O₇)₂(H₂O)₂]_n, is a polymer in which the repeating unit contains three zinc atoms, two hepta-dentate Hcit ligands (Hcit = citric acid trianion) and two coordinated water molecules, only half of which are independent due to one of the metal atoms lying on a centre of symmetry. The two independent cations both exhibit an octahedral geometry, but the way in which they are coordinate are different; while the Zn atom in a general position is bound to three Hcit ligands and one water molecule, the one at the centre of symmetry is coordinated by six O atoms from two symmetry-related Hcit ligands through the (protonated) hydroxyl and carboxylate groups. The three carboxylate groups coordinate to the Zn centres in three different ways, viz. chelating, bridging and a mixture of both, in an unusual coordination mode for citrate. The result is a two-dimensional structure parallel to (010), built up by a square-grid motif. Intermolecular O—H⋯O hydrogen bonds are present in the crystal structure

Related literature

For related literature, see: Albrecht et al. (2000 ); Dybtsev et al. (2004 ); Lightfoot & Sueddden (1999 ); Ma et al. (2000 ); Xie et al. (2004 , 2005 ); Yaghi & Li (1996 ); Yaghi & Rowsell (2006 ); Zhao et al. (2006 ); Zou et al. (2006 ).

Experimental

Crystal data

[Zn₃(C₆H₅O₇)₂(H₂O)₂]
M_r = 610.34
Monoclinic, P 2₁ /c
a = 6.1073 (5) Å
b = 15.3132 (12) Å
c = 9.7858 (8) Å
β = 102.79 (10)°
V = 892.48 (12) Å³
Z = 2
Mo Kα radiation
μ = 4.09 mm⁻¹
T = 298 (2) K
0.20 × 0.18 × 0.18 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ) T_min = 0.46, T_max = 0.48
4693 measured reflections
1749 independent reflections
1694 reflections with I > 2σ(I)
R_int = 0.026

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.233
S = 1.36
1648 reflections
143 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 1.18 e Å⁻³
Δρ_min = −1.06 e Å⁻³

Table 1
Selected bond lengths (Å)

Zn1—O7	2.270 (6)
Zn1—O4	2.285 (6)
Zn1—O3	2.319 (6)
Zn2—O5ⁱ	2.232 (7)
Zn2—O1W	2.244 (7)
Zn2—O6ⁱⁱ	2.316 (6)
Zn2—O2	2.338 (6)
Zn2—O1	2.371 (7)
Zn2—O7ⁱⁱ	2.485 (6)
Symmetry codes: (i) x-1, y, z-1; (ii) -x+1, -y, -z+1.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2ⁱⁱⁱ	0.82	1.88	2.691 (8)	172
O1W—H1WA⋯O7^iv	0.82	2.35	3.071 (10)	148
O1W—H1WB⋯O6^v	0.82	2.00	2.811 (10)	171
Symmetry codes: (iii) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iv) -x, -y, -z+1; (v) x-1, y, z.

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) and DIAMOND (Brandenburg, 2004 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808007642/bg2172sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808007642/bg2172Isup2.hkl

checkCIF report

Comment top

The rational design and syntheses of novel coordination polymers have achieved considerable progress in the field of supramolecular chemistry and crystal engineering, owing to their potential applications as gas storage (Yaghi & Rowsell, 2006), sensor technology (Albrecht et al., 2000), separation processes (Dybtsev et al., 2004), ion exchange (Yaghi & Li, 1996), luminescence (Zhao et al., 2006), magnetism (Ma et al., 2000), and catalysis (Zou et al., 2006), as well as due to their intriguing variety of architectures and topologies. Flexible di- and polycarboxylic acids are good candidates for the construction of novel metal-organic compounds as the carboxyl groups can form C—O—M—O four-membered rings with central metal ions, thereby improving the stability of transition metal-organic frameworks (MOFs). Furthermore, di- and polycarboxylic acids have two or more carboxyl groups that can be completely or partially deprotonated, which results in a rich variety of coordination modes and many interesting structures with higher dimensions. However, the hydroxyl polycarboxylates (HPCs), such as malate, citrate and tartrate, have been less studied as building blocks in the construction of metal-organic frameworks (Lightfoot & Sueddden,1999; Xie et al., 2004, 2005). Hydroxypolycarboxylic acids can act not only as hydrogen-bond acceptors but also as hydrogen-bond donors, depending on the number of deprotonated carboxyl group. In all known citrate-bridging compounds, the oxygen atoms of the alkoxyl or hydroxyl groups participate the coordination, which allows the formation of five- and six-membered rings, stabilizing the solid networks. In this paper, we report the synthesis and crystal structure of the title complex,(I).

As shown in the Scheme and in Fig. 1, the compound is a polymer where the repeating unit contains three zinc atoms, two hepta-dentate Hcit ligand (Hcit =citric acid trianion) and two coordinated water molecules, only half of which are independent due to the Zn1 atom lying on centre of symmetry.Both cations present an octahedral geometry; Zn2 is bound to three Hcit ligands and one coordinated water molecule, while the centrosymmetric Zn1 is coordinated by six oxygens from two symmetry related Hcit groups through the (protonated) hydroxyl and carboxylate groups.

The mean Zn—O bond length is 2.26 (2)Å (Table.1).

The carboxylate groups bind to the Zn centres in three different ways. The first group (O1—O2) chelates Zn2, the second (O4—O5) adopts a Zn1—Zn2 bridging mode while the third (O6—O7) chelates Zn2 while serving as a Zn1—Zn2 bridge as well. As a result of this unusual coordination mode via its three carboxylates groups and the hydroxy group, each citrate molecule binds four different Zn centres, viz.: to Zn1, in a tridentate way, and to three symmetry related Zn2, in bidentate or bridging fashion (Fig. 1). The result is a two-dimensional structure parallel to (010), built up by a square grid motive with cavity dimension of about 6.10*5.10 Å (Fig.2).

Related literature top

For related literature, see: Albrecht et al. (2000); Dybtsev et al. (2004); Lightfoot & Sueddden (1999); Ma et al. (2000); Xie et al. (2004, 2005); Yaghi & Li (1996); Yaghi & Rowsell (2006); Zhao et al. (2006); Zou et al. (2006)

Experimental top

ZnSO4(0.025 g, 0.013 mmol), citric acid(0.021 g, 0.016 mmol) and NaOH(0.048 mmol,0.12 mmol), were mixed in acetonitrile, and the mixture was heated for six hours under reflux. During the process stirring and influx were required. The resultant was then filtered to give a pure solution which was infiltrated by diethyl ether freely in a closed vessel. Four weeks later some single crystals of a suitable size for X-Ray diffraction analysis appeared.

Computing details top

Data collection: APEX2 (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) and DIAMOND (Brandenburg,2004); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Molecular diagram of (I), showing 30% probability displacement ellipsoids. In bold, the asymmetric unit. Symmetry codes: (i) x - 1, y, z - 1; (ii) -x + 1, -y, -z + 1, (iii) -x + 1, -y, -z + 2.
	Fig. 2. Two-dimensional network structure of complex (I). Colour codes: yellow, Zn1 polyhedra, pink, Zn2 polyhedra.

Poly[diaquadi-µ₄-citrato-trizinc(II)] top

Crystal data top

[Zn₃(C₆H₅O₇)₂(H₂O)₂]	F(000) = 608
M_r = 610.34	D_x = 2.271 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1749 reflections
a = 6.1073 (5) Å	θ = 2.5–26.0°
b = 15.3132 (12) Å	µ = 4.09 mm⁻¹
c = 9.7858 (8) Å	T = 298 K
β = 102.791 (1)°	Block, colourless
V = 892.48 (12) Å³	0.20 × 0.18 × 0.18 mm
Z = 2

Data collection top

Bruker APEXII area-detector diffractometer	1749 independent reflections
Radiation source: fine-focus sealed tube	1694 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.026
ϕ and ω scan	θ_max = 26.0°, θ_min = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −4→7
T_min = 0.46, T_max = 0.48	k = −18→18
4693 measured reflections	l = −12→11

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)] = 0.048	H-atom parameters constrained
wR(F²) = 0.233	w = 1/[σ²(F_o²) + (0.160P)² + 1.0412P] where P = (F_o² + 2F_c²)/3
S = 1.36	(Δ/σ)_max < 0.001
1648 reflections	Δρ_max = 1.18 e Å⁻³
143 parameters	Δρ_min = −1.07 e Å⁻³
1 restraint	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.021 (6)

Crystal data top

[Zn₃(C₆H₅O₇)₂(H₂O)₂]	V = 892.48 (12) Å³
M_r = 610.34	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 6.1073 (5) Å	µ = 4.09 mm⁻¹
b = 15.3132 (12) Å	T = 298 K
c = 9.7858 (8) Å	0.20 × 0.18 × 0.18 mm
β = 102.791 (1)°

Data collection top

Bruker APEXII area-detector diffractometer	1749 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	1694 reflections with I > 2σ(I)
T_min = 0.46, T_max = 0.48	R_int = 0.026
4693 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	1 restraint
wR(F²) = 0.233	H-atom parameters constrained
S = 1.36	Δρ_max = 1.18 e Å⁻³
1648 reflections	Δρ_min = −1.07 e Å⁻³
143 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.

Some reflections data are omiited may attributted to their bad reflections.

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

	x	y	z	U_iso*/U_eq
Zn1	0.5000	0.0000	1.0000	0.0150 (5)
Zn2	0.11561 (9)	0.09674 (4)	0.31681 (6)	0.0129 (5)
O1W	−0.1974 (13)	0.0915 (4)	0.4010 (8)	0.0543 (17)
H1WA	−0.2908	0.0542	0.3686	0.081*
H1WB	−0.1748	0.0841	0.4860	0.081*
O1	0.3216 (12)	0.0872 (4)	0.5521 (7)	0.0506 (17)
O2	0.3258 (10)	0.2105 (4)	0.4410 (7)	0.0473 (14)
O3	0.4296 (10)	0.1275 (4)	0.8697 (6)	0.0427 (13)
H3	0.3866	0.1764	0.8859	0.064*
O4	0.8310 (11)	0.0722 (5)	1.0802 (7)	0.0504 (16)
O5	1.0418 (12)	0.1871 (5)	1.1333 (7)	0.0566 (19)
O6	0.8360 (11)	0.0532 (4)	0.6858 (6)	0.0471 (15)
O7	0.6177 (11)	−0.0177 (4)	0.7974 (7)	0.0464 (15)
C1	0.3868 (13)	0.1633 (5)	0.5492 (8)	0.0383 (17)
C2	0.5471 (15)	0.2027 (5)	0.6762 (9)	0.0408 (19)
H2A	0.4776	0.2546	0.7046	0.049*
H2B	0.6825	0.2210	0.6478	0.049*
C3	0.6146 (12)	0.1423 (6)	0.8041 (8)	0.0349 (17)
C4	0.8172 (15)	0.1853 (6)	0.9036 (9)	0.0419 (19)
H4A	0.9423	0.1854	0.8574	0.050*
H4B	0.7793	0.2458	0.9168	0.050*
C5	0.8961 (12)	0.1437 (5)	1.0478 (8)	0.0356 (16)
C6	0.6918 (13)	0.0533 (5)	0.7569 (8)	0.0360 (17)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn1	0.0192 (7)	0.0147 (7)	0.0113 (7)	−0.0059 (3)	0.0041 (4)	0.0027 (3)
Zn2	0.0151 (6)	0.0123 (6)	0.0095 (6)	0.0008 (2)	−0.0014 (4)	0.0000 (2)
O1W	0.066 (4)	0.056 (4)	0.044 (4)	−0.001 (3)	0.018 (3)	−0.004 (3)
O1	0.061 (4)	0.038 (3)	0.044 (4)	−0.009 (3)	−0.008 (3)	0.005 (3)
O2	0.054 (4)	0.047 (3)	0.036 (3)	−0.007 (3)	0.000 (3)	0.002 (2)
O3	0.049 (3)	0.037 (3)	0.042 (3)	0.007 (3)	0.009 (3)	−0.003 (3)
O4	0.053 (4)	0.051 (4)	0.043 (4)	−0.015 (3)	−0.001 (3)	0.011 (3)
O5	0.060 (4)	0.055 (4)	0.046 (4)	−0.012 (3)	−0.007 (3)	0.008 (3)
O6	0.048 (3)	0.048 (4)	0.047 (3)	0.001 (3)	0.016 (3)	−0.002 (3)
O7	0.059 (4)	0.039 (3)	0.042 (3)	−0.005 (3)	0.012 (3)	0.003 (3)
C1	0.039 (4)	0.040 (4)	0.036 (4)	0.006 (3)	0.008 (3)	0.006 (3)
C2	0.047 (5)	0.033 (4)	0.040 (5)	−0.003 (3)	0.005 (4)	−0.001 (3)
C3	0.035 (4)	0.037 (4)	0.031 (4)	0.002 (3)	0.003 (3)	0.001 (3)
C4	0.045 (5)	0.041 (4)	0.038 (5)	−0.006 (3)	0.006 (4)	−0.003 (3)
C5	0.035 (4)	0.034 (4)	0.035 (4)	−0.002 (3)	0.002 (3)	−0.004 (3)
C6	0.036 (4)	0.041 (4)	0.029 (4)	−0.001 (3)	0.003 (3)	0.001 (3)

Geometric parameters (Å, º) top

Zn1—O7	2.270 (6)	O3—H3	0.82
Zn1—O7ⁱ	2.270 (6)	O4—C5	1.231 (10)
Zn1—O4ⁱ	2.285 (6)	O5—C5	1.266 (10)
Zn1—O4	2.285 (6)	O5—Zn2^iv	2.232 (7)
Zn1—O3ⁱ	2.319 (6)	O6—C6	1.237 (9)
Zn1—O3	2.319 (6)	O6—Zn2ⁱⁱⁱ	2.316 (6)
Zn2—O5ⁱⁱ	2.232 (7)	O7—C6	1.273 (10)
Zn2—O1W	2.244 (7)	O7—Zn2ⁱⁱⁱ	2.485 (6)
Zn2—O6ⁱⁱⁱ	2.316 (6)	C1—C2	1.526 (11)
Zn2—O2	2.338 (6)	C2—C3	1.538 (11)
Zn2—O1	2.371 (7)	C2—H2A	0.9700
Zn2—O7ⁱⁱⁱ	2.485 (6)	C2—H2B	0.9700
O1W—H1WA	0.8200	C3—C4	1.543 (11)
O1W—H1WB	0.8200	C3—C6	1.546 (11)
O1—C1	1.233 (10)	C4—C5	1.526 (11)
O2—C1	1.268 (10)	C4—H4A	0.9700
O3—C3	1.435 (9)	C4—H4B	0.9700

O7—Zn1—O7ⁱ	180.000 (1)	C3—O3—H3	105.1
O7—Zn1—O4ⁱ	94.0 (2)	Zn1—O3—H3	133.7
O7ⁱ—Zn1—O4ⁱ	86.0 (2)	C5—O4—Zn1	130.9 (5)
O7—Zn1—O4	86.0 (2)	C5—O5—Zn2^iv	101.2 (5)
O7ⁱ—Zn1—O4	94.0 (2)	C6—O6—Zn2ⁱⁱⁱ	96.6 (5)
O4ⁱ—Zn1—O4	180.0	C6—O7—Zn1	111.9 (5)
O7—Zn1—O3ⁱ	108.9 (2)	C6—O7—Zn2ⁱⁱⁱ	87.8 (5)
O7ⁱ—Zn1—O3ⁱ	71.1 (2)	Zn1—O7—Zn2ⁱⁱⁱ	144.8 (3)
O4ⁱ—Zn1—O3ⁱ	79.9 (2)	O1—C1—O2	121.4 (8)
O4—Zn1—O3ⁱ	100.1 (2)	O1—C1—C2	120.5 (7)
O7—Zn1—O3	71.1 (2)	O2—C1—C2	118.1 (7)
O7ⁱ—Zn1—O3	108.9 (2)	C1—C2—C3	115.6 (7)
O4ⁱ—Zn1—O3	100.1 (2)	C1—C2—H2A	108.4
O4—Zn1—O3	79.9 (2)	C3—C2—H2A	108.4
O3ⁱ—Zn1—O3	180.000 (1)	C1—C2—H2B	108.4
O5ⁱⁱ—Zn2—O1W	106.3 (3)	C3—C2—H2B	108.4
O5ⁱⁱ—Zn2—O6ⁱⁱⁱ	127.5 (3)	H2A—C2—H2B	107.4
O1W—Zn2—O6ⁱⁱⁱ	95.1 (2)	O3—C3—C2	111.3 (6)
O5ⁱⁱ—Zn2—O2	86.9 (2)	O3—C3—C4	112.7 (6)
O1W—Zn2—O2	104.5 (2)	C2—C3—C4	106.8 (7)
O6ⁱⁱⁱ—Zn2—O2	133.4 (2)	O3—C3—C6	108.5 (6)
O5ⁱⁱ—Zn2—O1	142.1 (2)	C2—C3—C6	109.4 (6)
O1W—Zn2—O1	87.3 (3)	C4—C3—C6	108.1 (6)
O6ⁱⁱⁱ—Zn2—O1	84.7 (2)	C5—C4—C3	116.7 (7)
O2—Zn2—O1	55.2 (2)	C5—C4—H4A	108.1
O5ⁱⁱ—Zn2—O7ⁱⁱⁱ	88.6 (3)	C3—C4—H4A	108.1
O1W—Zn2—O7ⁱⁱⁱ	147.6 (2)	C5—C4—H4B	108.1
O6ⁱⁱⁱ—Zn2—O7ⁱⁱⁱ	54.1 (2)	C3—C4—H4B	108.1
O2—Zn2—O7ⁱⁱⁱ	104.9 (2)	H4A—C4—H4B	107.3
O1—Zn2—O7ⁱⁱⁱ	98.5 (2)	O4—C5—O5	121.1 (7)
Zn2—O1W—H1WA	117.3	O4—C5—C4	123.8 (7)
Zn2—O1W—H1WB	114.3	O5—C5—C4	115.1 (7)
H1WA—O1W—H1WB	104.0	O6—C6—O7	121.4 (8)
C1—O1—Zn2	91.4 (5)	O6—C6—C3	118.1 (7)
C1—O2—Zn2	92.0 (5)	O7—C6—C3	120.4 (7)
C3—O3—Zn1	108.1 (4)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2^v	0.82	1.88	2.691 (8)	172
O1W—H1WA···O7^vi	0.82	2.35	3.071 (10)	148
O1W—H1WB···O6^vii	0.82	2.00	2.811 (10)	171

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

Experimental details

Crystal data
Chemical formula	[Zn₃(C₆H₅O₇)₂(H₂O)₂]
M_r	610.34
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	6.1073 (5), 15.3132 (12), 9.7858 (8)
β (°)	102.791 (1)
V (Å³)	892.48 (12)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	4.09
Crystal size (mm)	0.20 × 0.18 × 0.18

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2004)
T_min, T_max	0.46, 0.48
No. of measured, independent and observed [I > 2σ(I)] reflections	4693, 1749, 1694
R_int	0.026
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.233, 1.36
No. of reflections	1648
No. of parameters	143
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.18, −1.07

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg,2004), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Zn1—O7	2.270 (6)	Zn2—O6ⁱⁱ	2.316 (6)
Zn1—O4	2.285 (6)	Zn2—O2	2.338 (6)
Zn1—O3	2.319 (6)	Zn2—O1	2.371 (7)
Zn2—O5ⁱ	2.232 (7)	Zn2—O7ⁱⁱ	2.485 (6)
Zn2—O1W	2.244 (7)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2ⁱⁱⁱ	0.82	1.88	2.691 (8)	172.1
O1W—H1WA···O7^iv	0.82	2.35	3.071 (10)	147.9
O1W—H1WB···O6^v	0.82	2.00	2.811 (10)	170.6

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

Acknowledgements

The author is grateful to Gunagxi University for Nationalities for financial support.

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