Tris(1-ethyl-3-methyl­imidazolium) hexa­bromidoeuropate(III)

Michael Pellens; Ben Thijs; Kristof Van Hecke; Luc Van Meervelt; Koen Binnemans; Peter Nockemann

doi:10.1107/S1600536808018382

. 2008 Jun 21;64(Pt 7):m945. doi: 10.1107/S1600536808018382

Tris(1-ethyl-3-methylimidazolium) hexabromidoeuropate(III)

Michael Pellens ^a, Ben Thijs ^a, Kristof Van Hecke ^b, Luc Van Meervelt ^b, Koen Binnemans ^a, Peter Nockemann ^a,^*

PMCID: PMC2961749 PMID: 21202797

Abstract

The crystal structure of the title compound, (C₆H₁₁N₂)₃[EuBr₆], consists of 1-ethyl-3-methylimidazolium cations and centrosymmetric octahedral hexabromidoeuropate anions. The [EuBr₆]³⁻ anions are located at the corners and face-centres of the monoclinic unit cell. Characteristic hydrogen-bonding interactions can be observed between the bromide anions and the acidic H atoms of the imidazolium cations.

Related literature

For related literature, see: Arenz et al. (2005 ▶); Binnemans (2007 ▶); Chaumont & Wipff (2003 ▶); Driesen et al. (2004 ▶); Matsumoto et al. (2002 ▶); Nockemann et al. (2005 ▶, 2006 ▶, 2008 ▶); Reichert et al. (2006 ▶); Taubert (2004 ▶); Tsuda et al. (2001 ▶); Zhao et al. (2004 ▶).

Experimental

Crystal data

(C₆H₁₁N₂)₃[EuBr₆]
M _r = 964.87
Monoclinic,
a = 15.765 (1) Å
b = 12.729 (1) Å
c = 14.920 (1) Å
β = 90.36 (1)°
V = 2994.0 (4) Å³
Z = 4
Mo Kα radiation
μ = 10.12 mm⁻¹
T = 100 (2) K
0.18 × 0.17 × 0.16 mm

Data collection

Oxford Diffraction Gemini A Ultra diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008 ▶) T _min = 0.148, T _max = 0.200
17678 measured reflections
7019 independent reflections
5043 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.029
wR(F ²) = 0.099
S = 1.07
7019 reflections
290 parameters
H-atom parameters constrained
Δρ_max = 1.75 e Å⁻³
Δρ_min = −1.44 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2007 ▶); software used to prepare material for publication: PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808018382/hg2399sup1.cif

e-64-0m945-sup1.cif^{(22.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808018382/hg2399Isup2.hkl

e-64-0m945-Isup2.hkl^{(343.5KB, hkl)}

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

Acknowledgments

The authors acknowledge the FWO-Flanders for financial support (project No. G.0508.07). Financial support by the Katholieke Universiteit Leuven is also acknowledged (project Nos. GOA08/05 and IDO/05/005). Dr Oliver Presly from Oxford Diffraction Ltd is greatly acknowledged for the collection and processing of the diffraction data.

supplementary crystallographic information

Comment

Ionic liquids are increasingly attracting the attention of inorganic and materials chemists (Taubert, 2004; Reichert et al., 2006; Nockemann et al., 2008). Lanthanide compounds dissolved in ionic liquids have been of interest especially due to their photoluminescence behavior (Driesen et al., 2004; Binnemans, 2007; Nockemann et al., 2005). Experimental and theoretical studies on lanthanide ions in halide containing imidazolium ionic liquids have been investigated regarding electrochemical and spectroscopic properties (Arenz et al., 2005; Chaumont & Wipff, 2003; Tsuda et al., 2001). Imidazolium cations have been reported to yield low-melting lanthanide-containing ionic liquids like [BMIM]₅[Eu(SCN)₈] (Nockemann et al., 2006). An analogue structure to the title compound, [EMIM]₃[LaCl₆], has been reported previously (Matsumoto et al., 2002). The title compound crystallized unexpectedly after dissolving europium bis(trifluoromethylsulfonyl)imide hexahydrate, Eu(Tf₂N)₃.6H₂O in a mixture of [EMIM]Br and a nitrile functionalized imidazolium ionic liquid, 1-butyronitrile-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C₃CNMIM][Tf₂N]. The crystal structure of [EMIM]₃[EuBr₆] (Fig. 1) consists of 1-ethyl-3-methylimidazolium cations and octahedral [EuBr₆]^3- anions. The Eu—Br distances are in the range of 2.7793 (6) Å to 2.8187 (6) Å. The octahedral geometry of the two crystallographically independent [EuBr₆]^3- anions is slightly distorted with the surrounding of Eu1 more distorted than Eu2 with Br—Eu—Br angles ranging from 86.90 (2)° to 93.10 (2)° for Eu1, compared to angles ranging from 89.11 (2)° to 90.89 (2)° for Eu2. All bromine anions exhibit short contacts to neighboring H-atoms of imidazolium rings ranging from 2.76 Å to 2.90 Å. All three H-atoms of each of the three crystallographically independent imidazolium cations form hydrogen bonds with bromide atoms, which is exemplarily shown in Fig. 2 for one cation. In the packing of [EMIM]₃[EuBr₆], the [EuBr₆]^3- anions are located on the corners and face-centers of the monoclinic unit cell (Fig. 3).

Experimental

[EMIM]₃[EuBr₆] crystallized unintentionally after dissolving europium(III) bis(trifluoromethylsulfonyl)imide hexahydrate, Eu(Tf₂N)₃.6H₂O (0.5 g, 0.454 mmol) in a mixture of 5 ml of [EMIM]Br and 5 ml of a nitrile functionalized imidazolium ionic liquid, 1-butyronitrile-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C₃CNMIM][Tf₂N]. [EMIM]Br was purchased from IoLiTec. The nitrile functionalized imidazolium ionic liquid has been synthesized following a procedure that has been reported in the literature (Zhao et al. 2004). The title compound crystallized as small slightly yellow blocks.