Cation-π interactions: Complexes of guanidinium and simple aromatic systems

► We study pi-cation interactions. ► We analyze interactions established by the guanidinium cation. ► Stacking interactions formed by simple aromatic systems are examined. ► Computations are performed using the Truhlar DFT functional. ► The N-(5-methylpyridin-2-yl)guanidinium chloride crystal structure is presented.