catena-Poly[[bis­(1-ethyl-1H-imidazole-κN 3)cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN 3)cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN 3)cadmium]-di-μ-chlorido-[bis­(1-ethyl-1H-imidazole-κN 3)cadmium]]

Qian Xu; Run-Qiang Zhu

doi:10.1107/S160053681104894X

. 2011 Nov 30;67(Pt 12):m1850–m1851. doi: 10.1107/S160053681104894X

catena-Poly[[bis(1-ethyl-1H-imidazole-κN ³)cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN ³)cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN ³)cadmium]-di-μ-chlorido-[bis(1-ethyl-1H-imidazole-κN ³)cadmium]]

Qian Xu ^a,^*, Run-Qiang Zhu ^a

PMCID: PMC3238745 PMID: 22199622

Abstract

The asymmetric unit of the crystal structure of the title compound, [Cd₂Cl₄(C₅H₈N₂)₃]_n, contains two Cd^II cations, three 1-ethyl-1H-imidazole ligands, and four Cl⁻ anions. The two Cd^II atoms have quite different coordination environments: one is octahedrally coordinated by four Cl atoms and two N atoms from two 1-ethyl-1H-imidazole ligands, and the second is in a severely distorted fivefold coordination by four Cl atoms and one N atom from a 1-ethyl-1H-imidazole ligand. Adjacent Cd^II cations are interconnected alternately by pairs of chloride bridges, generating an infinite step-like chain along the a axis. One ethyl group of the 1-ethyl-1H-imidazole ligand is disordered over two sets of sites with a 0.668 (13):0.332 (13) site-occupancy ratio.

Related literature

For general background to compounds with organic framework structures and with ferroelectric properties, see: Ye et al. (2009 ▶); Zhang et al. (2009 ▶).

Experimental

Crystal data

[Cd₂Cl₄(C₅H₈N₂)₃]
M _r = 655.02
Monoclinic,
a = 15.227 (3) Å
b = 8.8651 (18) Å
c = 18.069 (4) Å
β = 110.34 (3)°
V = 2286.9 (8) Å³
Z = 4
Mo Kα radiation
μ = 2.34 mm⁻¹
T = 293 K
0.30 × 0.25 × 0.20 mm

Data collection

Rigaku SCXmini diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ▶) T _min = 0.501, T _max = 0.626
23098 measured reflections
5241 independent reflections
4674 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.028
wR(F ²) = 0.059
S = 1.17
5241 reflections
251 parameters
33 restraints
H-atom parameters constrained
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.78 e Å⁻³

Data collection: CrystalClear (Rigaku, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 1999 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S160053681104894X/vn2017sup1.cif

e-67-m1850-sup1.cif^{(28.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681104894X/vn2017Isup2.hkl

e-67-m1850-Isup2.hkl^{(256.7KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Cd1—N1	2.250 (2)
Cd1—N3	2.267 (2)
Cd1—Cl1	2.6259 (11)
Cd1—Cl1ⁱ	2.6995 (8)
Cd1—Cl2	2.7203 (8)
Cd1—Cl3	2.8930 (12)
Cd2—N5	2.227 (2)
Cd2—Cl3	2.4713 (8)
Cd2—Cl4	2.5120 (8)
Cd2—Cl2	2.6340 (11)
Cd2—Cl4ⁱⁱ	2.7526 (11)

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors are grateful to the starter fund of Southeast University for financial support to buy the X-ray diffractometer.

supplementary crystallographic information

Comment

The title compound, [C₁₅H₂₄Cd₂Cl₄N₆], (I), was prepared from 1-ethyl-1H-imidazole and cadmium(II) chloride in N,N-dimethylformamide. The X-ray crystal structure of the title complex at 298 K (Fig. 1) shows a novel infinite one-dimensional coordination chain along the a axis (Fig. 2). There are two types of Cd atoms with different coordination environments: Cd(1) is coordinated by two 2-ethyl imidazole ligands and four bridging Cl atoms, and Cd(2) is in severely distorted pentahedral coordination by four bridging Cl atoms, and one 2-ethyl imidazole ligand.

In order to examine possible structure phase transitions of compound (I), we measured its temperature-dependent dielectric constant. Large dielectric anomalies usually indicate structural changes such as paraelectric-to-ferroelectric phase transitions. Unfortunately, the dielectric constant of compound (I) goes smoothly in the temperature range 93–273 K, suggesting the absence of distinct phase transitions (Ye et al., 2009; Zhang et al., 2009).

Experimental

A mixture of CdCl2 (2.27 g, 10 mmol) and 2-ethyl imidazole (1.82 g, 20 mmol) in water was stirred for several minutes at room temperature, to which was then added 10 ml N,N-dimethylformamide. Colourless block-shaped crystals suitable for X-ray diffraction analysis were obtained by slow evaporation of the solution at room temperature over 2 weeks.