In an effort to deepen the understanding of nature of interactions between CuCl-based ionic liquids and thiophene, the electronic and topological properties of interactions between 1-butyl-3-methylimidazolium ([BMIM]+[Cu2Cl3]−) and thiophene (TS) have been investigated by the density functional theory. The occurrence of interactions caused by resonance effects between virtual orbitals of Cu and virtual orbitals of thiophene has been corroborated at the molecular level.