Kinetic and Mechanistic Study of the Homogenous Reactions of Ozone with Fe and Mn Ions by Ab-initio Calculations

In this work our aim is to present a new approach to the possible reaction mechanisms for the homogenous reactions of the ozone molecule with the manganese and ferrous ions by theoretical study of the structural properties of the reaction participants and the kinetic aspects of these reactions. Studying the structural properties of the reaction products (such as charge distributions, multiplicities and bond types) reveals that the probability of the reactions occurring by electron transfer from the ions of interest to the ozone molecule is much more than the other proposed mechanisms. We also investigated the reaction paths for the systems of interest by considering two probable paths for the ions attacking the ozone molecule: in the first path we considered the attacks of the Fe2+ and Mn2+ ions on the central oxygen atom of the ozone molecule and in the second one we considered the attacks of the ions on one of the terminal oxygen atoms of the ozone molecule. Both ferryl and manganyl ions (FeO2+ and MnO2+, respectively) show a coplanar transition state (TS) if the first path is followed, but there exists a non-planar TS if the second path is followed, which results in a not fully optimized structure. In comparison with the ferryl ion TS, there is an early downhill potential surface for the manganyl ion TS that lowers the activation energy. So manganese ion has a more effective role in the ozone dissociation process