2-Ethyl­imidazolium terephthalate

Run-Qiang Zhu; Chun-Hua Yu

doi:10.1107/S1600536811038578

. 2011 Sep 30;67(Pt 10):o2746. doi: 10.1107/S1600536811038578

2-Ethylimidazolium terephthalate

Run-Qiang Zhu ^a,^*, Chun-Hua Yu ^a

PMCID: PMC3201371 PMID: 22058806

Abstract

The asymmetric unit of the title compound, C₅H₉N₂ ⁺·C₈H₅O₄ ⁻, consists of one protonated 2-ethylimidazolium cation and two half terephthalate anions. The anions and cations are linked through N—H⋯O hydrogen bonds while the anions are associated via O—H⋯O interactions, resulting in a layered structure. The ethyl group of the cation is disordered over twosites of occupancies 0.812 (14) and 0.188 (14). The hydroxy H atoms of the anions are equally disordered over two symmetry-related sites.

Related literature

The title compound was synthesized as part of our search for ferroelectric materials. For general background to ferroelectric organic frameworks, see: Fu et al. (2009 ▶); Ye et al. (2006 ▶); Zhang et al. (2008 ▶, 2010 ▶). For related structures, see: Tian (2007 ▶); Qu (2007 ▶).

Experimental

Crystal data

C₅H₉N₂ ⁺·C₈H₅O₄ ⁻
M _r = 262.26
Triclinic,
a = 6.4587 (13) Å
b = 7.0719 (14) Å
c = 14.688 (3) Å
α = 78.60 (3)°
β = 78.77 (3)°
γ = 89.50 (3)°
V = 644.7 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.10 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 = 0.970, T _max = 0.980
6568 measured reflections
2933 independent reflections
2197 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.060
wR(F ²) = 0.171
S = 1.07
2933 reflections
194 parameters
H-atom parameters constrained
Δρ_max = 0.29 e Å⁻³
Δρ_min = −0.24 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, 2005 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811038578/vm2120sup1.cif

e-67-o2746-sup1.cif^{(17.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811038578/vm2120Isup2.hkl

e-67-o2746-Isup2.hkl^{(143.9KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811038578/vm2120Isup3.cml

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
O4—H4A⋯O4ⁱ	0.82	1.67	2.452 (3)	160
O2—H2⋯O2ⁱⁱ	0.82	1.64	2.450 (3)	170
N2—H2C⋯O1ⁱⁱⁱ	0.86	1.90	2.739 (3)	166
N1—H1D⋯O3	0.86	1.86	2.713 (3)	173

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

Acknowledgments

This work was supported by Southeast University.

supplementary crystallographic information

Comment

With reference to the compounds 2(C₄H₇N₂)⁺.C₈H₄O₄^2-.2(C₄H₆N₂).4(H₂O) (Qu, 2007) and 2(C₃H₅N)⁺.C₈H₄O₄^2-(Tian, 2007), we synthesized the title compound to find ferroelectric material by dielectric measurements of compound as a function of temperature (Fu et al., 2009; Ye et al., 2006; Zhang et al., 2008; Zhang et al., 2010). In the range from 190 K to near its melting point (m.p.>423 K), no dielectric anomaly was observed.

In the crystal structure (Fig. 1) determined at 293 K, we observe short O···O distances in the range 2.448 (3)–2.450 (3) Å between the interacting carboxylic acid groups. The H atoms attached to O2 and O4 are disordered. The O···O distances are much shorter than the N···O distances which are 2.714 (3) and 2.738 Å (Table 1).

Experimental

A mixture of 2-ethyl imidazole (2.4 g, 25 mmol), terephthalic acid (25 mmol) in water was stirred for several days at ambient temperature. Colourless block crystals were obtained.