THE WATER EXCHANGE-REACTION FOR M(H2O)62+ SYSTEMS

Molecular orbital calculation as the ab initio level were carried out for the exchange reaction of water with M(H2O)6(2+). Here M2+ = V, Mn, Fe and Ni with the electronic configurations (t2g)3, (t2g)3(e(g))2, (t2g)6) and (t2g)6(e(g))2, respectively. The molecular orbital calculations correspond to gas-phase reactions; i.e., the second hydration sphere and bulk solvent effects are not taken into account. The optimized geometries for the M(H2O)6(2+) complexes are in excellent agreement with experiment. The M(H2O)7(2+) species are calculated to be transition states for all four examples. The amount of M-O bond elongation on going from the ground to transition state correlates with measured value of The activation energies for V2+, Mn2+ and Ni2+ are in reasonable agreement with experiment.