Structure, Energies, and Vibrational Frequencies of Solvated Li+ in Ionic Liquids: Role of Cation Type

Faina Dubnikova, Yehuda Zeiri

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

This study examines the structure of five ionic liquids all of them containing bis[(trifluoromethyl)sulfonyl]imide (TFSI) as the anion with five different cations: Dimethylammonium, N-propylammonium, N-methyl-1-propylpiperidinium, N-methyl-3-methylpyridinium, and N-methylpyrrolidinium. This study is based on quantum chemical calculations of structure, energetics, and vibrational spectroscopy associated with solutions of Li+ in the five ionic liquids examined. We have shown that the Li-TFSI ion-pair stabilization is 2.5-4 fold larger than those of the ion pairs of five cations with TFSI. A large number of different species containing LikTFSInCtm (Ct represent one of five cations studied, k, n, m = 0-2) were examined in detail. The results suggest that Li-(TFSI)2 is a highly stable species and may be responsible for the transport of Li ions in these ionic liquids. The vibrational analysis suggests that the high stability of the Li-TFSI ion pair is mainly due to Coulomb interaction between the Li ion and two oxygen atoms bound to the two sulfur atoms in the TFSI anion. This O-Li-O bond exhibits stretching and bending modes that may allow monitoring of these ion pairs.

Original languageEnglish
Pages (from-to)3079-3087
Number of pages9
JournalJournal of Physical Chemistry A
Volume120
Issue number19
DOIs
StatePublished - 19 May 2016

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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