Density functional theoretical study on the potential energy surface of the propene hydrogenation catalyzed by metal Ir4 cluster

Using density functional theory(DFT), the reaction mechanism of propene hydrogenation catalyzed by metal Ir-4 cluster were explored in detail theoretically. At B3LYP level, the geometries of stationary points (reactions, intermediates, transition states and product) were optimized and the ground state potential energy surface was ploted. The calculated results suggest that for the propene hydrogenation catalyzed by metal Ir-4 cluster, the reaction may follow three reaction channels, which is c, d and e. In the major reaction channel c, the H-atom at If, site first transforms to intermediate 1 after surmounting TSR-1, followed by the addition of H-atom to the side C of propene, leading to forming intermediate isomer 3. After that, the H-atom at Ir-2 site can add to the middle C, passing through transition state TS3-5, intermediate 5 and transition state TS5-P respectively. Channel c is the most feasible reaction channel on the PES on both kinetic and thermodynamic considerations. As the highest transition states in channel d and e are a little higher than that of in channel-c, they are less competitive and belong to minor channels.