The interaction energy between an ion pair diminishes with separation distance r as a function of 1/r, whereas the interaction energy between two rotating dipoles diminishes as 1/r6. This means that ion-ion interactions are much longer range than dipole-dipole interactions. In fact, all so-called "van der Waals" interactions diminish as 1/r6, whether it be dipole-dipole, dipole-induced dipole, or induced dipole-induced dipole (London). To compare the range of interaction strength, compute the value of r when 1/r is only 1.0% of its value at r=1.
At that point, r =
Now compute the value of r when 1/r6 is only 1.0% of its value at r=1. Then r =
Those numbers are roughly how many Angstroms away from molecular contact that the force of interaction operates.