Salt-Bridge Transition State for the Charge Separation Co(H2O)42+ → CoOH(H2O)2+ + H3O+

The transition state of the charge separation Co(H2O)42+ → CoOH(H2O)2+ + H3O+ is located by density functional theory calculations. The H3O+ unit is already separated from the CoOH(H2O)2+ moiety by more than 3 A, and the charge centers form a Co2+−OH-−H3O+ salt bridge, lowering the barrier for the reaction. The transition state is calculated to lie 166 kJ/mol above the products, including zero-point corrections, which compares favorably with the 110 ± 20 kJ/mol kinetic energy release measured in an earlier work (Faherty, K. P.; et al. J. Phys. Chem. A 2001, 105, 10054). The deviation is interpreted as fractions of the energy going into rotational and vibrational excitation of the products.