The nature of interactions between N-butylpyridinium tetrafluoroborate and thiophenic compounds: A theoretical investigation

In an effort to understand the nature of the interactions between pyridinium-based ionic liquids and thiophenic compounds, the electronic and topological properties of the interactions between N-butylpyridinium tetrafluoroborate ([BPY](+)[BF4](-)) and thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT) have been investigated by density functional theory. The most stable structure of the [BPY](+)[BF4](-) ion-pair indicated that hydrogen bonding interactions between fluorine atoms on [BF4](-) anions and C2-H2 on the pyridinium ring play an important role in the formation of the ion-pair. The NBO and AIM analyses indicate the occurrence of pi-pi stacking interactions. The electron density at bond critical points and Wiberg bond indices are correlated with the interacting distances of H center dot center dot center dot F interactions, so electron density and Wiberg bond index can demonstrate the interacting strength of H center dot center dot center dot F hydrogen bonds. The interaction energies suggest that DBT adsorbs prior to the other compounds on N-butylpyridinium tetrafluoroborate ionic liquid. (C) 2013 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.