Density functional and Moller-Plesset second-order perturbation (MP2) calculations have been carried out on various model cation-pi complexes formed through the interactions of Mg2+, Ca2+, and NH4+ cations with benzene, p-methylphenol, and 3-methylindole. Partial hydration of the metal cations was also considered in these model studies to monitor the effect of hydration of cations in cation-pi interactions. The binding energies of these complexes were computed from the fully optimized structures using coupled cluster calculations including triple excitations (CCSD(T)) and Gaussian-G4-MP2 (G4MP2) techniques. An analysis of the charge sharing between the donor (the pi-systems) and the acceptors (the cations) together with the partitioning of total interaction energies revealed that the strong and weak cation-pi interactions have similar electrostatic interaction properties. Further decomposition of such electrostatic terms into their multipolar components showed the importance of the charge-dipole, charge-quadrupole, and charge-octopole terms in shaping the electrostatic forces in such interactions. The computed vibrational spectra of the complexes were analyzed for the specific cation-pi interaction modes and have been shown to contain the signature of higher order electrostatic interaction energy components (quadrupole and octopole) in such interactions.