The exchange between bulk and coordinated water is of fundamental interest as a measure of the intrinsic kinetic lability of metal ions.  This rate is relevant to toxicity, catalysis, magnetic resonance imaging, and other effects.  For octahedral mono- and dicationic aquo complexes, these exchange processes occur via an interchange pathway that has more or less dissociative character.  Rates vary by a factor of 10,  being the slowest and  being one of the fastest for octahedral complexes.  Charge has a significant influence on these rates but non-electrostatic effects are also important.