Poly[[tetra­aqua­(μ6-2,2′-diiodo­biphenyl-4,4′,5,5′-tetra­carboxyl­ato)dizinc(II)] dihydrate]

Wang, Y.; Li, Y.-Q.; Shen, Y.-Z.

doi:10.1107/S1600536808026494

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 9| September 2008| Pages m1203-m1204

doi:10.1107/S1600536808026494

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Poly[[tetraaqua(μ₆-2,2′-diiodobiphenyl-4,4′,5,5′-tetracarboxylato)dizinc(II)] dihydrate]

Yan Wang,^a Yue-Qin Li ^a and Ying-Zhong Shen ^a ^*

^aApplied Chemistry Department, School of Material Science & Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, People's Republic of China
^*Correspondence e-mail: yz_shen@nuaa.edu.cn

(Received 23 June 2008; accepted 18 August 2008; online 30 August 2008)

In the title compound, {[Zn₂(C₁₆H₄I₂O₈)(H₂O)₄]·2H₂O}_n, two crystallographically independent Zn^II atoms are each located on a twofold rotation axis. Both Zn^II atoms are in distorted octahedral coordination geometries: one is coordinated by six O atoms from four carboxylate groups, while the other is coordinated by two carboxylate groups and four water molecules. The tetracarboxylate ligand molecules connect the Zn^II atoms, completing a three-dimensional metal–organic framework. O—H⋯O hydrogen bonds link the metal–organic framework with the uncoordinated water molecules.

Related literature

For related literature, see: Beringer et al. (1953 ); Cordes et al. (2006 ); Garay et al. (2007 ); Noro et al. (2007 ); Qiu et al. (2007 ); Wang et al. (2007 ); Weng et al. (2007 ); Williams et al. (2005 ).

Experimental

Crystal data

[Zn₂(C₁₆H₄I₂O₈)(H₂O)₄]·2H₂O
M_r = 816.83
Monoclinic, C 2
a = 10.9466 (16) Å
b = 9.8135 (14) Å
c = 11.3913 (17) Å
β = 100.187 (3)°
V = 1204.4 (3) Å³
Z = 2
Mo Kα radiation
μ = 4.62 mm⁻¹
T = 295 (2) K
0.40 × 0.30 × 0.20 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: numerical (SADABS; Bruker, 2000 ) T_min = 0.20, T_max = 0.39
3279 measured reflections
2126 independent reflections
1767 reflections with I > 2σ(I)
R_int = 0.040

Refinement

R[F² > 2σ(F²)] = 0.052
wR(F²) = 0.088
S = 0.97
2126 reflections
155 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 1.07 e Å⁻³
Δρ_min = −1.01 e Å⁻³
Absolute structure: Flack (1983 ), 870 Friedel pairs
Flack parameter: 0.00 (4)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5A⋯O3ⁱ	0.85	2.35	3.074 (9)	144
O5—H5A⋯O1ⁱⁱ	0.85	2.30	2.967 (9)	136
O5—H5B⋯O7ⁱⁱⁱ	0.85	1.97	2.807 (15)	169
O6—H6A⋯O3^iv	0.85	2.01	2.772 (10)	148
O6—H6B⋯O7	0.85	2.50	3.113 (16)	129
O7—H7B⋯O4	0.85	2.23	2.910 (16)	137
Symmetry codes: (i) -x, y, -z+1; (ii) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iii) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (iv) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+1]$ .

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); 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: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808026494/is2308sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808026494/is2308Isup2.hkl

checkCIF report

Comment top

Interest in the self-assembled construction of coordination polymers is rapidly increasing not only owing to their potential applications in gas storage, ion-exchange, catalysis, electrical conductivity, nonlinear optics and magnetism, but also because of their fascinating diversified architectures and topologies (Cordes et al., 2006; Garay et al., 2007). Multicarboxylate ligands, such as 1,4-benzenedicarboxylate (Williams et al., 2005), 1,3,5-benzenetricarboxylate (Noro et al., 2007) and biphenyl-3,3',4,4'-tetracarboxylate (Weng et al., 2007), have been extensively employed in the construction of novel metal-organic complexes with multidimensional networks and interesting properties. In view of the excellent coordination capability of multicarboxylate anions and the solubility of diaryliodonium salts, we employed 2,2'-diiodobiphenyl-4,4',5,5'-tetracarboxylic acid (H₄L), as an organic building unit to generate three dimensional metal-organic framework. In this paper, we describe the synthesis of a novel zinc(II) complexes, namely, [Zn₂(L)(H₂O)_4.2H₂O]_n, by reaction of Zn(NO₃)₂.6H₂O and H₄L via hydrothermal method, which was characterized by IR, elemental analysis and X-ray single-crystal analysis. To the best of our knowledge, transition metal coordination polymers based on diiodobiphenyl tetracarboxylate has never been reported before. This work may provide useful information for the further design of metal-organic frameworks with interesting architectures using diiodobiphenyl tetracarboxylate as versatile multidentate ligands.

The title complex crystallizes in the monoclinic system, space group C2, with two crystallographically independent Zn^II atoms each located on a twofold axis. As shown in Fig. 1, both Zn^II atoms are in distorted octahedral configurations and are connected by carboxylate groups. The Zn1 center is coordinated by four carboxylate groups, that is, 4(4')-COO^- from two different L^4- ligands in a monodentate fashion (O1 and O1ⁱⁱ) and 5(5')-COO^- from other two L^4- ligands in a bischelating fashion (O3ⁱ, O4ⁱ, O3ⁱⁱⁱ and O4ⁱⁱⁱ). In contrast, the Zn2 center is coordinated by four O atoms of water (O5, O6, O5ⁱⁱ and O6ⁱⁱ) and two carboxylate groups: 4(4')-COO^- from two different L^4- ligands in a monodentate fashion (O2 and O2ⁱⁱ). The Zn–O bond lengths fall in the range of 1.953 (6)–2.368 (7) Å, similar to those in other zinc-tetracarboxylate coordination polymers (Wang et al., 2007). Hence, the L^4- ligand acts as a octadentate ligand, linking six different Zn^II atoms to form a three-dimensional metal–organic framework (Fig. 2); the 5,5'-carboxyl groups adopt a bidentate bridging mode, while the 4,4'-carboxyl groups exhibit a bis(monodentate) bridging mode. Within the L^4- ligand, the two phenyl rings are almost perpendicular to each other with the dihedral angle of 88.6 (1)°, and the dihedral angles between 4,5(4',5')-carboxylate groups and the plane of correspondingly linked phenyl rings are respectively 72.0 (1) and 27.3 (1)°.

There are various O—H···O hydrogen bonds associated with the coordinated water molecules, uncoordinated water molecules and carboxylate O atoms in the title complex, linking the metal-organic framework with the uncoordinated water molecules.

Related literature top

For related literature, see: Beringer et al. (1953); Cordes et al. (2006); Garay et al. (2007); Noro et al. (2007); Qiu et al. (2007); Wang et al. (2007); Weng et al. (2007); Williams et al. (2005).

Experimental top

All chemicals were of analytical grade and used without further purification. According to the reported procedure (Beringer et al., 1953; Qiu et al., 2007), H₄L was prepared by iodine substitution of the N-methyl protected 3,3',4,4'-biphenyltetracarboxylicdianhydride, hydrolysis by 3M KOH and acidification by 6.5 M HCl to pH 1.0. The hydrothermal reaction was performed in a 25 ml Teflon-lined stainless steel autoclave under autogenous pressure. An solution of H₄L (58 mg, 0.1 mmol), Zn(NO₃)₂.6H₂O (59 mg, 0.2 mmol), 2 ml EtOH and 8 ml H₂O was adjusted to pH 7 with 1 M NaOH solution and then heated at 140 °C for 3 days. After the sample was cooled slowly to room temperature, colourless crystals were obtained and air-dried by filtration ca 60% yield based on Zn. Anal. calcd for C₈H₈O₇IZn: C 23.53, H 1.97%; Found: C 23.48, H 2.02%. IR (KBr discs, ν_max/cm^-1): 3379(vs), 1599(s), 1562(s), 1539(s), 1472(w), 1401(vs), 1318(w), 1254(m), 1163(w), 1098(m), 953(w), 915(w), 873(m), 846(m), 802(m), 678(w), 605(w), 543(w).

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); 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).

Figures top

	Fig. 1. A view of the title complex, depicting the Zn^II coordination environment. Displacement ellipsoids are drawn at the 30% probability level. The solvent water molecules and H atoms have been omitted for clarity [symmetry codes: (i) -x + 1/2, y - 1/2, -z + 1; (ii) -x, y, -z + 1; (iii) x - 1/2, y - 1/2, z].
	Fig. 2. Packing diagram of the title complex viewed along the a axis, showing a three-dimensional metal-organic framework. The dashed lines indicate hydrogen bonds.

Poly[[tetraaqua(µ₆-2,2'-diiodobiphenyl-4,4',5,5'-tetracarboxylato)dizinc(II)] dihydrate] top

Crystal data top

[Zn₂(C₁₆H₄I₂O₈)(H₂O)₄]·2H₂O	F(000) = 780
M_r = 816.83	D_x = 2.252 Mg m⁻³
Monoclinic, C2	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: C 2y	Cell parameters from 762 reflections
a = 10.9466 (16) Å	θ = 2.8–18.3°
b = 9.8135 (14) Å	µ = 4.62 mm⁻¹
c = 11.3913 (17) Å	T = 295 K
β = 100.187 (3)°	Block, colourless
V = 1204.4 (3) Å³	0.40 × 0.30 × 0.20 mm
Z = 2

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	2126 independent reflections
Radiation source: fine-focus sealed tube	1767 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.040
ϕ and ω scans	θ_max = 26.0°, θ_min = 2.8°
Absorption correction: numerical (SADABS; Bruker, 2000)	h = −9→13
T_min = 0.20, T_max = 0.39	k = −11→12
3279 measured reflections	l = −14→14

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)] = 0.052	H-atom parameters constrained
wR(F²) = 0.088	w = 1/[σ²(F_o²) + (0.0207P)²] where P = (F_o² + 2F_c²)/3
S = 0.98	(Δ/σ)_max < 0.001
2126 reflections	Δρ_max = 1.07 e Å⁻³
155 parameters	Δρ_min = −1.01 e Å⁻³
1 restraint	Absolute structure: Flack (1983), 870 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.00 (4)

Crystal data top

[Zn₂(C₁₆H₄I₂O₈)(H₂O)₄]·2H₂O	V = 1204.4 (3) Å³
M_r = 816.83	Z = 2
Monoclinic, C2	Mo Kα radiation
a = 10.9466 (16) Å	µ = 4.62 mm⁻¹
b = 9.8135 (14) Å	T = 295 K
c = 11.3913 (17) Å	0.40 × 0.30 × 0.20 mm
β = 100.187 (3)°

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	2126 independent reflections
Absorption correction: numerical (SADABS; Bruker, 2000)	1767 reflections with I > 2σ(I)
T_min = 0.20, T_max = 0.39	R_int = 0.040
3279 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.052	H-atom parameters constrained
wR(F²) = 0.088	Δρ_max = 1.07 e Å⁻³
S = 0.98	Δρ_min = −1.01 e Å⁻³
2126 reflections	Absolute structure: Flack (1983), 870 Friedel pairs
155 parameters	Absolute structure parameter: 0.00 (4)
1 restraint

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
I1	0.31728 (8)	0.46912 (8)	1.05780 (7)	0.0770 (3)
Zn1	0.0000	0.52673 (14)	0.5000	0.0296 (4)
Zn2	0.0000	0.94976 (18)	0.5000	0.0373 (4)
O1	0.1541 (6)	0.6253 (7)	0.5567 (6)	0.0404 (17)
O2	0.1099 (7)	0.8284 (7)	0.6272 (6)	0.0399 (18)
O3	0.3711 (6)	0.8475 (7)	0.5451 (6)	0.0454 (19)
O4	0.4839 (6)	0.9757 (8)	0.6747 (6)	0.0543 (19)
O5	−0.1277 (5)	0.9419 (7)	0.6112 (5)	0.0454 (18)
H5A	−0.2029	0.9518	0.5787	0.054*
H5B	−0.1254	0.8743	0.6577	0.054*
O6	0.1005 (8)	1.1179 (7)	0.5892 (7)	0.057 (2)
H6A	0.1232	1.1982	0.5746	0.068*
H6B	0.1538	1.0920	0.6488	0.068*
O7	0.3492 (12)	1.2077 (15)	0.7470 (11)	0.116 (4)
H7A	0.3346	1.2367	0.8145	0.139*
H7B	0.4010	1.1431	0.7670	0.139*
C1	0.1734 (8)	0.7220 (12)	0.6301 (8)	0.032 (2)
C2	0.4137 (9)	0.8752 (11)	0.6505 (9)	0.038 (3)
C3	0.3828 (10)	0.7879 (9)	0.7465 (9)	0.030 (2)
C4	0.2774 (9)	0.7090 (10)	0.7331 (8)	0.027 (2)
C5	0.2594 (9)	0.6187 (9)	0.8224 (9)	0.036 (2)
H5	0.1881	0.5652	0.8124	0.043*
C6	0.3468 (9)	0.6073 (9)	0.9266 (8)	0.033 (2)
C7	0.4536 (8)	0.6899 (9)	0.9425 (7)	0.028 (2)
C8	0.4700 (9)	0.7767 (9)	0.8536 (9)	0.031 (2)
H8	0.5411	0.8305	0.8636	0.038*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
I1	0.0650 (6)	0.0980 (7)	0.0621 (5)	−0.0337 (6)	−0.0053 (4)	0.0436 (5)
Zn1	0.0288 (9)	0.0325 (9)	0.0269 (8)	0.000	0.0029 (7)	0.000
Zn2	0.0294 (8)	0.0396 (10)	0.0414 (9)	0.000	0.0021 (7)	0.000
O1	0.030 (4)	0.042 (4)	0.047 (5)	0.000 (4)	0.000 (3)	−0.011 (3)
O2	0.037 (4)	0.049 (5)	0.032 (4)	0.015 (4)	−0.001 (3)	0.001 (3)
O3	0.049 (5)	0.050 (5)	0.040 (4)	0.009 (4)	0.015 (4)	0.004 (4)
O4	0.041 (4)	0.054 (5)	0.062 (5)	−0.014 (4)	−0.006 (3)	0.032 (4)
O5	0.027 (3)	0.057 (5)	0.053 (4)	0.012 (4)	0.009 (3)	0.009 (4)
O6	0.079 (6)	0.035 (4)	0.048 (5)	−0.012 (4)	−0.010 (4)	0.010 (3)
O7	0.118 (10)	0.116 (9)	0.124 (10)	0.014 (8)	0.049 (8)	0.031 (8)
C1	0.028 (5)	0.039 (6)	0.029 (5)	−0.006 (5)	0.008 (4)	0.009 (5)
C2	0.027 (6)	0.041 (7)	0.043 (7)	0.004 (5)	−0.003 (5)	0.008 (5)
C3	0.035 (6)	0.021 (5)	0.033 (6)	−0.005 (4)	0.006 (5)	−0.002 (4)
C4	0.035 (6)	0.029 (5)	0.017 (5)	0.006 (5)	0.000 (4)	0.008 (4)
C5	0.026 (6)	0.035 (6)	0.047 (7)	−0.004 (5)	0.009 (5)	0.001 (5)
C6	0.039 (6)	0.028 (5)	0.028 (6)	0.007 (5)	−0.002 (5)	0.003 (4)
C7	0.023 (5)	0.042 (6)	0.022 (5)	0.007 (4)	0.007 (4)	−0.006 (4)
C8	0.021 (5)	0.030 (6)	0.043 (6)	−0.008 (4)	0.006 (5)	0.001 (4)

Geometric parameters (Å, º) top

I1—C6	2.085 (9)	O5—H5A	0.85
Zn1—O1	1.953 (6)	O5—H5B	0.85
Zn1—O1ⁱ	1.953 (6)	O6—H6A	0.85
Zn1—O4ⁱⁱ	2.090 (6)	O6—H6B	0.85
Zn1—O4ⁱⁱⁱ	2.090 (6)	O7—H7A	0.85
Zn1—O3ⁱⁱⁱ	2.368 (7)	O7—H7B	0.85
Zn1—O3ⁱⁱ	2.368 (7)	C1—C4	1.488 (12)
Zn2—O5	2.047 (5)	C2—C3	1.475 (13)
Zn2—O5ⁱ	2.047 (5)	C3—C4	1.375 (13)
Zn2—O2ⁱ	2.085 (7)	C3—C8	1.415 (14)
Zn2—O2	2.085 (7)	C4—C5	1.389 (12)
Zn2—O6	2.138 (8)	C5—C6	1.391 (13)
Zn2—O6ⁱ	2.138 (7)	C5—H5	0.9300
O1—C1	1.258 (12)	C6—C7	1.408 (12)
O2—C1	1.251 (12)	C7—C8	1.359 (12)
O3—C2	1.239 (11)	C7—C7^iv	1.509 (17)
O4—C2	1.251 (11)	C8—H8	0.9300

O1—Zn1—O1ⁱ	120.6 (4)	C1—O2—Zn2	138.1 (6)
O1—Zn1—O4ⁱⁱ	102.7 (3)	C2—O3—Zn1^v	84.9 (6)
O1ⁱ—Zn1—O4ⁱⁱ	91.0 (3)	C2—O4—Zn1^v	97.5 (6)
O1—Zn1—O4ⁱⁱⁱ	91.0 (3)	H5A—O5—H5B	106.00
O1ⁱ—Zn1—O4ⁱⁱⁱ	102.7 (3)	H6A—O6—H6B	104.00
O4ⁱⁱ—Zn1—O4ⁱⁱⁱ	152.3 (5)	H7A—O7—H7B	103.00
O1—Zn1—O3ⁱⁱⁱ	144.0 (3)	O2—C1—O1	125.7 (9)
O1ⁱ—Zn1—O3ⁱⁱⁱ	85.8 (2)	O2—C1—C4	115.9 (9)
O4ⁱⁱ—Zn1—O3ⁱⁱⁱ	100.5 (3)	O1—C1—C4	118.3 (10)
O4ⁱⁱⁱ—Zn1—O3ⁱⁱⁱ	57.4 (3)	O3—C2—O4	119.9 (10)
O1—Zn1—O3ⁱⁱ	85.8 (2)	O3—C2—C3	119.6 (9)
O1ⁱ—Zn1—O3ⁱⁱ	144.0 (3)	O4—C2—C3	120.5 (9)
O4ⁱⁱ—Zn1—O3ⁱⁱ	57.4 (3)	C4—C3—C8	118.5 (8)
O4ⁱⁱⁱ—Zn1—O3ⁱⁱ	100.5 (3)	C4—C3—C2	122.9 (9)
O3ⁱⁱⁱ—Zn1—O3ⁱⁱ	84.1 (3)	C8—C3—C2	118.4 (9)
O5—Zn2—O5ⁱ	175.7 (4)	C3—C4—C5	120.2 (9)
O5—Zn2—O2ⁱ	92.0 (3)	C3—C4—C1	123.3 (8)
O5ⁱ—Zn2—O2ⁱ	85.5 (3)	C5—C4—C1	116.3 (9)
O5—Zn2—O2	85.5 (3)	C4—C5—C6	120.7 (9)
O5ⁱ—Zn2—O2	92.0 (3)	C4—C5—H5	120
O2ⁱ—Zn2—O2	110.3 (4)	C6—C5—H5	120
O5—Zn2—O6	94.9 (3)	C5—C6—C7	119.6 (9)
O5ⁱ—Zn2—O6	88.4 (3)	C5—C6—I1	119.6 (7)
O2ⁱ—Zn2—O6	163.0 (3)	C7—C6—I1	120.8 (7)
O2—Zn2—O6	85.7 (3)	C8—C7—C6	118.8 (9)
O5—Zn2—O6ⁱ	88.4 (3)	C8—C7—C7^iv	119.3 (9)
O5ⁱ—Zn2—O6ⁱ	94.9 (3)	C6—C7—C7^iv	121.9 (8)
O2ⁱ—Zn2—O6ⁱ	85.7 (3)	C7—C8—C3	122.2 (9)
O2—Zn2—O6ⁱ	163.0 (3)	C7—C8—H8	119
O6—Zn2—O6ⁱ	79.0 (4)	C3—C8—H8	119
C1—O1—Zn1	128.9 (6)

O1ⁱ—Zn1—O1—C1	49.0 (8)	O3—C2—C3—C8	150.4 (9)
O4ⁱⁱ—Zn1—O1—C1	147.9 (8)	O4—C2—C3—C8	−28.7 (14)
O4ⁱⁱⁱ—Zn1—O1—C1	−56.4 (9)	C8—C3—C4—C5	−1.3 (16)
O3ⁱⁱⁱ—Zn1—O1—C1	−83.0 (9)	C2—C3—C4—C5	173.6 (8)
O3ⁱⁱ—Zn1—O1—C1	−156.9 (8)	C8—C3—C4—C1	173.6 (9)
C2ⁱⁱⁱ—Zn1—O1—C1	−67.9 (9)	C2—C3—C4—C1	−11.5 (17)
C2ⁱⁱ—Zn1—O1—C1	176.4 (8)	O2—C1—C4—C3	−70.1 (13)
O5—Zn2—O2—C1	132.2 (10)	O1—C1—C4—C3	112.1 (12)
O5ⁱ—Zn2—O2—C1	−44.3 (10)	O2—C1—C4—C5	105.0 (11)
O2ⁱ—Zn2—O2—C1	41.7 (9)	O1—C1—C4—C5	−72.8 (12)
O6—Zn2—O2—C1	−132.6 (11)	C3—C4—C5—C6	0.4 (15)
O6ⁱ—Zn2—O2—C1	−158.2 (10)	C1—C4—C5—C6	−174.8 (9)
Zn2—O2—C1—O1	−28.8 (16)	C4—C5—C6—C7	1.1 (14)
Zn2—O2—C1—C4	153.7 (7)	C4—C5—C6—I1	−179.4 (7)
Zn1—O1—C1—O2	−50.1 (14)	C5—C6—C7—C8	−1.7 (13)
Zn1—O1—C1—C4	127.4 (8)	I1—C6—C7—C8	178.8 (6)
Zn1^v—O3—C2—O4	5.3 (9)	C5—C6—C7—C7^iv	175.1 (8)
Zn1^v—O3—C2—C3	−173.8 (9)	I1—C6—C7—C7^iv	−4.4 (11)
Zn1^v—O4—C2—O3	−6.1 (10)	C6—C7—C8—C3	0.8 (13)
Zn1^v—O4—C2—C3	173.0 (8)	C7^iv—C7—C8—C3	−176.1 (9)
O3—C2—C3—C4	−24.4 (15)	C4—C3—C8—C7	0.7 (16)
O4—C2—C3—C4	156.5 (10)	C2—C3—C8—C7	−174.4 (8)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5A···O3ⁱ	0.85	2.35	3.074 (9)	144
O5—H5A···O1^vi	0.85	2.30	2.967 (9)	136
O5—H5B···O7ⁱⁱⁱ	0.85	1.97	2.807 (15)	169
O6—H6A···O3^vii	0.85	2.01	2.772 (10)	148
O6—H6B···O7	0.85	2.50	3.113 (16)	129
O7—H7B···O4	0.85	2.23	2.910 (16)	137

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

Experimental details

Crystal data
Chemical formula	[Zn₂(C₁₆H₄I₂O₈)(H₂O)₄]·2H₂O
M_r	816.83
Crystal system, space group	Monoclinic, C2
Temperature (K)	295
a, b, c (Å)	10.9466 (16), 9.8135 (14), 11.3913 (17)
β (°)	100.187 (3)
V (Å³)	1204.4 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	4.62
Crystal size (mm)	0.40 × 0.30 × 0.20

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Numerical (SADABS; Bruker, 2000)
T_min, T_max	0.20, 0.39
No. of measured, independent and observed [I > 2σ(I)] reflections	3279, 2126, 1767
R_int	0.040
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.052, 0.088, 0.98
No. of reflections	2126
No. of parameters	155
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.07, −1.01
Absolute structure	Flack (1983), 870 Friedel pairs
Absolute structure parameter	0.00 (4)

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), 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
O5—H5A···O3ⁱ	0.85	2.35	3.074 (9)	144
O5—H5A···O1ⁱⁱ	0.85	2.30	2.967 (9)	136
O5—H5B···O7ⁱⁱⁱ	0.85	1.97	2.807 (15)	169
O6—H6A···O3^iv	0.85	2.01	2.772 (10)	148
O6—H6B···O7	0.85	2.50	3.113 (16)	129
O7—H7B···O4	0.85	2.23	2.910 (16)	137

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

Acknowledgements

We gratefully acknowledge the National 863 Research Project (2006 A A03Z219), the Natural Science Foundation of Jiangsu Province (BK2007199), the `Liu Da Ren Cai' Foundation of Jiangsu Province (06-E-021), the State Postdoctoral Foundation of China (No. 2006040932) and the Postdoctoral Foundation of Jiangsu Province (No. 0602008B).

References

Beringer, F. M., Drexler, M., Gindler, E. M. & Lumpkin, C. C. (1953). J. Am. Chem. Soc. 75, 2705–2708. CrossRef CAS Web of Science Google Scholar
Bruker (2000). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cordes, D. B., Hanton, L. R. & Spicer, M. D. (2006). Inorg. Chem. 45, 7651–7664. Web of Science CSD CrossRef PubMed CAS Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Garay, A. L., Pichon, A. & James, S. L. (2007). Chem. Soc. Rev. 36, 846–855. CrossRef PubMed CAS Google Scholar
Noro, S., Akutagawa, T. & Nakamura, T. (2007). Cryst. Growth Des. 7, 1205–1208. Web of Science CSD CrossRef CAS Google Scholar
Qiu, Z.-M., Chen, G., Zhang, Q.-Y. & Zhang, S.-B. (2007). Eur. Polym. J. 43, 194–204. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wang, J.-J., Gou, L., Hu, H.-M., Han, Z.-X., Li, D.-S., Xue, G.-L., Yang, M.-L. & Shi, Q.-Z. (2007). Cryst. Growth Des. 7, 1514–1521. Web of Science CSD CrossRef CAS Google Scholar
Weng, D.-F., Zheng, X.-J., Li, L.-C., Yang, W.-W. & Jin, L.-P. (2007). Dalton Trans. pp. 4822–4828. Web of Science CSD CrossRef Google Scholar
Williams, C. A., Blake, A. J., Hubberstey, P. & Schroder, M. (2005). Chem. Commun. pp. 5435–5437. Web of Science CSD CrossRef Google Scholar

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