The crystal structure of dichlorido-bis(3-methyl- 3-imidazolium-1-ylpropionato-κ 2 )-cadmium(II), C 14 H 20 CdCl 2 N 4 O 4

C 14 H

The molecular structure is shown in the figure.Table 1 contains crystallographic data and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters.

Source of material
1-Carboxypropyl-3-methylimidazolium chloride was preprared according to the method reported in reference [6].CdO (1 mmol) with an excess of 1-carboxypropyl-3-methylimidazolium chloride (1.5 mmol) were added into a methanol-water (1:1) mixture (20 mL).This mixture was stirred for 24 h at 353 K.After slow evaporation of the filtrate for one week at room temperature, colorless block crystals were obtained.

Experimental details
All hydrogen atoms were refined using riding coordinates with U iso (H) = 1.2U eq (C), whereas the methyl hydrogen atoms were placed in the best location with U iso (H) = 1.5U eq (C).

Comment
COOH-functional ionic liquids have been designed, synthesized and explored in various applications such as separation and extraction [7,8], catalysis [9,10] and ionic liquid-based scavenger [11] and so on.Recently, some of them have also been utilized to construct coordination compounds [12,13].For example, Han et al. [12] reported the first example of lanthanide coordination frameworks, and demonstrated that the introduction of a functional group opens up new possibilities in crystal engineering and the material fabrication.
Due to the limited investigation on COOH-functional ionic liquids, we used the prepared carboxypropyl-3-methylimidazolium chloride to directly react with CdO, and obtained a mononuclear Cd(II) coordination compound, which is different to the one-dimensional polymeric structure obtained from ionic liquid 1-carboxymethyl-3-methylimidazolium chloride and Cd(OH) 2 [14].
Structural representation and the atom numbering scheme of the title compound are provided in Figure 1.The asymmetric unit of the title structure consists of one Cd 2+ cation, two neutral 3-methyl-3-imidazolium-1-ylpropionate ligands and two chloride ligands.The central metal ion Cd(II) attains a strongly distorted octahedral geometry.Here the equatorial plane is formed by three oxygen atoms of two organic ligands and one Cl − anion, while the axial positions are respectively occupied by another Cl − anion and the remaining coordinated O atom of one organic ligand.The bond distances of Cd-O [2.288 (2)-2.585(3) Å] and Cd-Cl [2.4452 (9)-2.4930( 9) Å] fall in the desired ranges.The alkyl chain is nearly vertical to the imidazole ring plane 86.7°, similar to that of zwitterionic compound [15] and salt with Cl Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

Table  :
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å  ).