Water exchange dynamics of manganese(II), cobalt(II), and nickel(II) ions in aqueous solution

The first row transition metal ions Mn(2+), Co(2+), and Ni(2+) have been studied by classical umbrella sampling molecular dynamics simulations. The water exchange mechanisms, estimates of reaction rates, as well as structural changes during the activation process are discussed. Mn(2+) was found to react via an I(A) mechanism, whereas Co(2+) and Ni(2+) both proceed via I(D). Reaction rate constants are generally higher than those obtained by experiment but the simply constructed metal(II) ion-water potential reproduces the relative order quite well.