Investigation of structures, binding energies and thermodynamic properties of ionic liquid [Mim+][B(CN)4−]

In the present study, intermolecular interactions between cation and anion in methylimidazolium tetracyanoborate ionic liquid [Mim+][B(CN)4−] have been studied using B3LYP/6-311G(2d,2p) level of theory. Four ion pairs were found on the potential energy surface. The most stable structures contain both N∙∙∙H–N and N∙∙∙H–C hydrogen bonds. Structures, interaction energies, hydrogen bonding, physical and thermodynamic properties as well as topological properties have been investigated. The effect of different solvents on the stability of complexes and monomers was examined. The thermodynamic properties of ion pairs were calculated using COSMO-RS model. NICS used for indicating of aromaticity of cation ring upon complexation. The NBO results show that in all the ion pairs, the charge transfer taking place from anion to cation. Also, the LPN * (N–H) and LPN* (C-H) donor–acceptor interactions are most important interactions in these complexes. The QTAIM results reveal that all interactions have electrostatic nature. It is predicted that N…H-N interaction is stronger than N…H-C one.