The crystal structure of dichlorido-bis(3-methyl- 3-imidazolium-1-ylpropionato-κ 2 O , O ′ )-zinc(II), C

C 14 H 20 Cl 2 N 4 O 4 Zn, monoclinic, P 2 1 / n (no. 14), a = 8.562(2) Å, b = 27.953(8) Å, c = 8.804(2) Å, β = 117.092(4) ° , V = 1875.9(9) Å 3 , Z = 4, R gt ( F ) = 0.0441, w R ref ( F 2 ) = 0.1031, T = 296 K.


Experimental details
All hydrogen atoms in ring and methylene groups were refined using riding coordinates with U iso (H) = 1.2U eq (C), whereas the hydrogen atoms of methyl group were placed in the idealized location with U iso (H) = 1.5U eq (C).

Comment
The functionalization of traditional ionic liquids can enrich the number of ionic liquids, extend their applications, and attract more and more attention as an effective approach for a special task.Carboxyl-functionalized ionic liquids not only exhibit designability and diversity of ionic liquid but also possess coordination ability derived from carboxyl groups to construct the various coordinating polymers.These unique properties make them crucial in absorption and separation, catalysis, proton conduction, and other significant fields [6][7][8].
For example, Huang et al. [8] reported a novel clean method for separating zinc and cobalt using a carboxyl-functionalized ionic liquid and a higher separation effect on zinc and cobalt.Ma and co-workers [7] have synthesized a series of carboxylfunctionalized imidazolium salts, and further investigation demonstrated that their hydrosilylation reactions exhibited higher styrene conversion and β-adduct selectivity.In this work, we used the prepared carboxyethyl-3-methylimidazolium chloride to react with zinc, and obtained a mononuclear Zn (II) coordination compound.
The title compound crystallizes in the monoclinic system, and its asymmetric unit, as shown in figure, contains one Zn 2+ cation, two Cl − anions, and two 3-methyl-3-imidazolium-1-ylpropionate zwitter ions, similar to those reported in a Cd(II) complex [9].The central Zn 2+ cation is four-coordinated in a slightly distorted tetrahedral geometry with two Cl − anions and two oxygen atoms of two carboxylate groups.In this tetrahedron, the bond distance of Cl1-Zn1 and Cl2-Zn1 is 2.2556(12) Å and 2.2879(11) Å, respectively.Meanwhile, the bond lengths of Zn1-O2 (1.955(3) Å) and Zn1-O4 (1.988(2) Å) fall in the desired ranges.Interestingly, the alkyl chain of carboxyethyl-3-methylimidazolium adopts a highly bent conformation.The torsion angles of O1-C1-C2-C3 and C1-C2-C3-N1 are 6.1 (5)°and 60.2(5)°, respectively.In contrast, the carbon atoms of methyl and ethyl groups, closest to the ring, and imidazole ring are approximately coplanar, because the torsion angles of C7-N2-C6-C5 and C3-N1-C5-C6 are −178.5(4)Å and 176.4(4)Å.This conformation of cation is the same as those of the anhydrous zwitterionic compound [10] and salt with acid anion [5] in the crystal structure, but different from that in another Zn(II) complex [11].In the crystal packing, neighboring complexes are connected by numerous weak C-H⋯O and C-H⋯Cl interactions.In addition, the C⋯C short contact with a distance of 3.399 Å between two adjacent imidazolium rings is present, forming a one-dimensional chain along the a-axis of the crystal.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.Research funding: The School-level Innovation Fund project of Xinxiang Institute of Engineering (2023ZK-1) is gratefully acknowledged.

Conflict of interest statement:
The authors declare no conflicts of interest regarding this article.

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