Poly[hexa­aqua­bis­(μ3-hepta­nedioato-κ3 O:O′:O′′)dimagnesium]

Xia-Xia Guo; Jian-li Lin

doi:10.1107/S1600536811015492

. 2011 May 7;67(Pt 6):m665. doi: 10.1107/S1600536811015492

Poly[hexaaquabis(μ₃-heptanedioato-κ³ O:O′:O′′)dimagnesium]

Xia-Xia Guo ^a, Jian-li Lin ^a,^*

PMCID: PMC3120615 PMID: 21754577

Abstract

In the title compound, [Mg₂(C₇H₁₀O₄)₂(H₂O)₆]_n, the Mg^II ion is coordinated by three aqua ligands and three O atoms from three heptanedioato ligands in a distorted octahedral geometry. Each heptanedioato ligand bridges three Mg atoms, generating polymeric layers parallel to the bc plane. The polymeric layers related by translation along the a axis interact further via O—H⋯O hydrogen bonds, which consolidate the crystal packing.

Related literature

For general background to microporous coordination polymers, see: Borkowski & Cahill (2006 ▶); Dimos et al. (2002 ▶); Kim et al. (2001 ▶). For related structures, see: Liu et al. (2009 ▶).

Experimental

Crystal data

[Mg₂(C₇H₁₀O₄)₂(H₂O)₆]
M _r = 236.51
Monoclinic,
a = 14.311 (3) Å
b = 8.2080 (16) Å
c = 9.1280 (18) Å
β = 96.22 (3)°
V = 1065.9 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.18 mm⁻¹
T = 293 K
0.1 × 0.1 × 0.1 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.982, T _max = 0.982
8118 measured reflections
1880 independent reflections
1440 reflections with I > 2σ(I)
R _int = 0.040

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.121
S = 1.16
1880 reflections
136 parameters
H-atom parameters constrained
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.46 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 1998 ▶); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 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.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811015492/cv5076sup1.cif

e-67-0m665-sup1.cif^{(15.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811015492/cv5076Isup2.hkl

e-67-0m665-Isup2.hkl^{(92.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5C⋯O2ⁱ	0.84	1.92	2.741 (3)	165
O5—H5D⋯O6ⁱⁱ	0.84	1.99	2.818 (3)	168
O6—H6C⋯O2ⁱⁱⁱ	0.82	2.07	2.882 (3)	170
O6—H6D⋯O5ⁱⁱⁱ	0.82	2.06	2.879 (3)	171
O7—H7A⋯O4^iv	0.83	1.94	2.725 (3)	158
O7—H7B⋯O2^v	0.79	2.26	2.798 (3)	127

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

This project was supported by the Scientific Research Fund of Ningbo University (grant No. XKL069) and the Education Department of Zhejiang Province. Grateful thanks are also extended to the K. C. Wong Magna Fund in Ningbo University.

supplementary crystallographic information

Comment

The past decade has witnessed enormous expansion of research on robust microporous coordination polymers (Borkowski et al., 2006; Dimos et al., 2002; Kim et al., 2001). For such purpose, design and synthesis of novel coordination polymers have been focused on organic ligands, others have reported lists of complexs used dicarboxylic acids. In this contribution, we report the crystal structure of the title compound (I).

In (I) (Fig. 1), two carboxylate groups of pimelato (pim^2–) ligand display different coordination behaviour - in the O1–C1–O2 group only one O1 atom coordinate one Mg center, while the O3–C7–O4 carboxylate group coordinate two Mg centers in an syn/anti mode. The Mg atoms are six-coordinated by three oxygen atoms from three pim^2– anions and three aqua ligands to complete a distorted MgO₆ octahedra with the Mg–O distances in the range of 1.999 (3)–2.156 (2) Å. The trans– and cisoid– O–Mg–O angles lie in the region 81.4 (1)–98.7 (1)° and 168.5 (1)– 171.8 (1)°.The Mg coordination sphere in (I) is similar to that observed in Mg₂(H₂O)₆(BTEC) (Liu et al., 2009). The Mg²⁺ ions are bridged by the pimelate anions, forming the polymeric layers parallel to (100) (Fig. 2). When the Mg atom and the pim^2– anions are treated as 3– nodes, the two-dimensional layers can be best described as (4.8²) topological network. Intermolecular O—H···O hydrogen bonds (Table 1) between the aqua ligand and carboxylate oxygen atoms make a contribution to stabilization of the three-dimensional framework.

Experimental

Dropwise addition of 1 M NaOH (1.0 ml) to a stirred aqueous solution of (0.1248 g, 0.5 mmol) MgSO₄.7H₂O in 5.0 ml H₂O produced pale-white Mg(OH)₂.xH₂O precipitate, which was separated by centrifugation and washed with distilled water several times until no detectable SO₄^2– anions in the supernatant. Subsequently, the 0.0815 g (0.5 mmol) pimelic acid was dissolved completely with 15 ml H₂O, and then the precipitate was added. The resulting mixture was further stirred for 30 min and then filtered. The white filtrate (pH = 5.70) was allowed to stand at room temperature. Slow evaporation for several days afforded colourless platelet-like crystals.