A study of the conformers of the N,N-diethyl-N-methyl-N-propylammonium ion by means of infrared spectroscopy and DFT calculations

An Infrared Spectroscopy Study of the Conformational Evolution of the Bis(trifluoromethanesulfonyl)imide Ion in the Liquid and in the Glass State

“…Indeed, the ratio of the intensities, , of the lines attributable to the different rotamers is proportional to their relative concentration. From the changes of as a function of temperature, one can verify the Boltzmann distributions of the concentrations of conformers and calculate the energy difference between the rotamers [16,23].…”

A Study of the Conformers of the (Nonafluorobutanesulfonyl)imide Ion by Means of Infrared Spectroscopy and Density Functional Theory (DFT) Calculations

“…The higher energy conformers span the entire energy range up to ~19 kJ/mol. The vibration frequencies and their intensity were calculated for both IM 14 conformers by means of two models: the B3LYP is commonly used for calculations on ions composing ionic liquids [6,10,[13][14][15]; the BPE0 model, that has been reported to give better agreement with the experimental vibration frequencies than the B3LYP model in the bis(trifluoromethanesulfonyl)imide ion [15]. The unscaled calculated frequency values obtained by both methods are reported in the supporting materials, in Table S3, while the absorption spectra generated from these values between 400 and 1500 cm −1 with no scaling factor are reported in Figure 1b,c. The comparison of the experimental absorbance with the calculated vibration lines provides evidence that the liquid shows the presence of the two anion conformers at both temperatures.…”

New Experimental Evidences Regarding Conformational Equilibrium in Ammonium−Bis(trifluoromethanesulfonyl)imide Ionic Liquids

“…[6] We recently investigated two ammonium based ILs, namely N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl) imide (TMPA-TFSI) and N-trimethyl-N-hexylammonium bis(trifluoromethanesulfonyl)imide (TMHA-TFSI), sharing a common anion and differing in the length of the alkyl chain of the cation (see Figure 1). [13] However, from the calculations the energy difference between these two conformers is as low as 2.2 kJ/mol, and therefore in the liquid state both of them are usually present. [10][11][12] It can be found in two different conformational geometries: the transoid one with a C2 symmetry is more stable than the cisoid one, which has a C1 symmetry.…”

“…TFSI is a well known anion, with large applications in electrochemistry, where it has found use, for instance, as component of several types of battery electrolytes [7][8][9] or as additive in dye-sensitized solar cells. [13] The two conformers give rise to different Raman and infrared spectra, as indicated by experimental and computational studies. [13] However, from the calculations the energy difference between these two conformers is as low as 2.2 kJ/mol, and therefore in the liquid state both of them are usually present.…”

“…[10][11][12] It can be found in two different conformational geometries: the transoid one with a C2 symmetry is more stable than the cisoid one, which has a C1 symmetry. [13,14] From these experimental studies it is possible to obtain the value of the enthalpy difference between the two conformers of TFSI in condensed environments. [13] The two conformers give rise to different Raman and infrared spectra, as indicated by experimental and computational studies.…”