Study of hydrogen bond between the anion and cation in the methyl ethyl imidazolium bis (tri fluoro methylsulfonylmethane) amide ionic liquid using density functional theory (DFT)

Subject Areas :

Hossein Azizi Toupkanloo ¹ (Teacher at University of Neyshabur)

Received: 2017-03-14 Accepted : 2017-05-27 Published : 2017-08-23

Keywords: Hydrogen bond, Anion-Cation Interaction, density functional theory, Ionic liquid,

Abstract :

It is crucially important to understand the structural properties of ionic liquids. In the present work, the structures of cation, anion and cation-anion ion pair [C2mim][NTF2] imidazolium-based ionic liquid systematically using density functional theory (DFT) at B3LYP/6-311G ** were optimized. The zero point energy and basis set superposition errors corrections were obtained using the results of frequency calculations at the B3LYP level with the mentioned basis sets, without considering any scaling. According to the calculated Mulliken charge distributions on the anion and cations, the interaction between 〖[NTF_2]〗^- and 〖[C_2 mim]〗^+ is expected to be occured in more positive or negative charged regions. Various conformers ion pair [C2mim][NTF2] were optimized. The most stable structure of [C_2 mim][NTF_2 ] ion pair indicates that hydrogen bonding interactions between oxygen and nitrogen atoms on 〖[NTF_2]〗^- anion and the hydrogen atoms on the imidazolium ring play a main role in the formation of ion pair. It was found that there exist four hydrogen bonded in the most conformer of [C_2 mim][NTF_2 ]. Compared with the isolated 〖[C_2 mim]〗^+, the strengths of C-H bonds in the imidazolium ring were weaken more or less due to the formation of the intermolecular hydrogen bonds.