ion-dipole interaction (rus. взаимодействие, ион-дипольное) — interaction between an ion and a molecule with a permanent or induced dipole moment.


The ion-dipole interaction, similarly to van der Waals interactions of neutral molecules, refers to weak noncovalent bonds. It is due to interactions between ions and polar groups of molecules (or induced dipoles). The energy of the ion-dipole bond typically lies within the range of 50-200 kJ/mol.

There are two main types of ion-dipole interactions.

1. Orientation interaction (ion – permanent dipole). Potential of ion-dipole interaction (), when the dipole can rotate (almost) freely, such as in liquids (hereinafter, the thermal rotation energy is assumed to be significantly greater than the electrostatic energy, which occurs at larger ion-dipole distances), the magnitude of interaction is inversely proportional to the fourth power of the distance and to the temperature:


2. Induction interaction (ion – induced dipole). The dipole moment induced by an external field, in this particular case the field of the ion, has permanent orientation determined by the field. It is proportional to the charge of the ion and polarisability of the molecule and inversely proportional to the square of the distance. Correspondingly, the interaction potential is inversely proportional (as in the case of a permanent dipole moment) to the fourth power of the distance and directly proportional to the square of the charge and (isotropic) polarisability of the molecule: 

As in the case of other intermolecular interactions, the ion charge can interact with higher multipole moments, but such interaction is generally weaker and inversely proportional to higher powers of the distance, i.e. is of much shorter range.


  • Ioffe Ilya N.


  1. Peter Atkins. Physical Chemistry. Oxford University Press, 2nd ed. — 1000 pp.