| Abstract: | Molecular interactions of a representative pyrrolidinium-based ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(triflorosulfonyl)- imide (BMPyrr]TFSI]) with dimethyl sulfoxide (DMSO) and acetonitrile (AN) have been analyzed in this work. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and density functional theory (DFT) calculations are used in the investigation, while excess infrared spectra and two-dimensional correlation spectroscopy are used to explore the data in detail. It has been found that the molecular solvents can interact with TFSI- (mainly with S=O and weakly with S–N–S group). AN interacts feebly with BMPyrr+ as compared with the strong interaction of DMSO. The strength of the interactions depends on the electron donating ability of the solvent. Upon mixing, hydrogen bonds regarding C?Hs in cation and S–N–S in anion are weakened, while that regarding S=O in anion is strengthened. Among the C?Hs which are connected directly with the N of the cation, C1?H is the main interaction site for both DMSO and AN. This means that C1?H is the most acidic hydrogen in pyrrolidinium cation. |
