Tris(2-ethyl-1H-imidazole-κN 3)(terephthalato-κO)zinc(II)

Quan-An Xie; Gui-Ying Dong; Ya-Mei Yu; Yong-Gang Wang

doi:10.1107/S1600536809014755

. 2009 Apr 25;65(Pt 5):m576. doi: 10.1107/S1600536809014755

Tris(2-ethyl-1H-imidazole-κN ³)(terephthalato-κO)zinc(II)

Quan-An Xie ^a,^b,^*, Gui-Ying Dong ^b, Ya-Mei Yu ^b, Yong-Gang Wang ^a

PMCID: PMC2977618 PMID: 21583804

Abstract

The title compound, [Zn(C₈H₄O₄)(C₅H₈N₂)₃], has a neutral monomeric structure in which one terephthalate dianion and three 2-ethyl-1H-imidazole ligands coordinate to the Zn^II ion in a distorted tetrahedral geometry. The methyl group of one of the ethyl groups is disordered over two positions with occupancies of 0.66 (2) and 0.34 (2). In the crystal structure, molecules are linked into a three-dimensional hydrogen-bonded network by intermolecular N—H⋯O interactions involving the uncoordinated carboxylate O atoms.

Related literature

For the crystal structures of related Zn^II complexes, see: Chen et al. (1994 ▶); Kimura et al. (1991 ▶); Yang et al. (2002 ▶).

Experimental

Crystal data

[Zn(C₈H₄O₄)(C₅H₈N₂)₃]
M _r = 517.90
Monoclinic,
a = 11.548 (2) Å
b = 11.759 (2) Å
c = 18.719 (4) Å
β = 91.79 (3)°
V = 2540.7 (8) Å³
Z = 4
Mo Kα radiation
μ = 1.01 mm⁻¹
T = 293 K
0.30 × 0.25 × 0.22 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.742, T _max = 0.812
13021 measured reflections
5719 independent reflections
3534 reflections with I > 2σ(I)
R _int = 0.086

Refinement

R[F ² > 2σ(F ²)] = 0.073
wR(F ²) = 0.114
S = 1.12
5719 reflections
317 parameters
16 restraints
H-atom parameters constrained
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.28 e Å⁻³
Absolute structure: Flack (1983 ▶), 2826 Friedel pairs
Flack parameter: 0.049 (15)

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 1999 ▶); 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.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809014755/ci2775sup1.cif

e-65-0m576-sup1.cif^{(25.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809014755/ci2775Isup2.hkl

e-65-0m576-Isup2.hkl^{(280KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Zn1—O1	1.947 (4)
Zn1—N3	2.018 (4)
Zn1—N5	2.023 (5)
Zn1—N1	2.044 (5)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O4ⁱ	0.86	1.88	2.717 (7)	165
N4—H4⋯O3ⁱⁱ	0.86	1.94	2.787 (7)	167
N6—H6⋯O3ⁱⁱⁱ	0.86	1.96	2.797 (7)	163

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

Acknowledgments

The authors thank the China University of Mining and Technology (Beijing) and Hebei Polytechnic University for supporting this work.

supplementary crystallographic information

Comment

Metal complexes with imidazole can serve as biomimetic ligands for histidine residues which frequently participate in the co-ordination spheres of metalloenzyme active sites. In particular, carboxylate-histidine-zinc triad systems are regularly observed, and play important roles in the catalytic processes of more than thirty zinc enzymes (Chen et al., 1994). However, crystal structure reports of such model zinc complexes containing neutral imidazole ligands are rather rare, and so far only a few examples have been presented (Kimura et al., 1991; Chen et al., 1994). Here, we report the synthesis and crystal structure of the title complex.

The title compound is a monomeric zinc(II) complex (Fig. 1). The Zn^II center is four coordinated by three monodentate 2-ethyl-1H-imidazole ligands and by a monodentate terephthalate group, forming a distorted tetrahedral N3,O geometry. The Zn—N bond lengths are in the range 2.014 (6)–2.047 (7) Å and the Zn—O distance is 1.943 (6) Å (Table 1). The most distorted bond angle is O1—Zn1—N1 at 100.5 (3)°.

The N—H···O hydrogen bonds (Table 2) formed between three uncoordinated 2-ethyl-H-imidazole N atoms and two uncoordinated carboxylate O atoms, resulted in a three-dimensional hydrogen-bonded network.

Experimental

The title compound was synthesized by a solvothermal method from Zn(NO₃)₂.6H₂O (29.8 mg, 0.1 mmol), terephthalic acid (77.6 mg,0.4 mmol), 2-ethylimidazole (38.4 mg, 0.4 mmol) and water-ethanol mixed slovent (3 ml). The starting mixture was homogenized and transferred to a sealed Teflon-lined solvothermal bomb (bomb volume: 25 ml) and heated at 433 K for 3 d under autogenous pressure. After cooling in a water bath, colourless crystals were obtained, which were washed and rinsed with distilled water and absolute ethyl alcohol (yield: 51.8% on the basis of Zn(NO₃)₂.6H₂O). Analysis calculated (%) for C₂₃H₂₈N₆O₄Zn: C 53.34, H 5.45, N 16.23%; found: C 53.18, H 5.43, N 16.13.