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چکیده
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In this work we propose to study the intermolecular interactions of an alicyclic ether-functionalized ammonium based ionic liquid by ab initio calculations. This substance contains [RmPyrr] (1-R-1-methyl pyrrolidinium) with R=MeOCH2CH2- as cation and NTF2- as anion. Our aim is to elucidate the characteristic features of the interactions of cation and anion in this ionic liquid with each other and with lithium metal. The Gaussian 09 program is used for first-principle calculations. Geometry optimization for cationic, anionic and complex species are carried out in the framework of density functional theory by using the popular 6-311 G ** basis set. The optimized geometries are characterized by harmonic analysis. The bonding features of all the studied species are analyzed by means of the natural bond orbital (NBO) and the natural population analysis (NPA). Also the nature of the bonding is analysed by using the Bader's atoms in molecule (AIM) approach.
Six structures were optimized: firstly, the cation, secondly the cation together with lithium, thirdly, the anion, at the fourth, anion with lithium, at the fifth, cation with anion and finally cation with anion and lithium metal. The interaction sites in each pair are found and the nature of the interaction is analyzed by considering the electron density gradient using AIM method. For a better understanding of these interactions, a population analysis of the NBO calculations for the nearest bonds and atoms is used. The charge transfer between ions and second order perturbation stabilization energy for interactions are computed with the NBO program implemented in gaussian09 package. The results are finally compared to those for discrete ions.
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