Title: Theoretical Studies of Chemical Reactions—A Fascinating World of Chemistry from Gas-Phase Elementary Reactions through Nanostructure Formation and Homogeneous Catalysis to Reactions of Metalloenzymes
Abstract: Abstract Theoretical/computational studies of chemical reactions provide insight into detailed pathways and energy profiles that are not easily available from experiments. Although finding the potential energy profile for ground-state reactions of small molecular systems has become routine, there are many challenges in theoretical studies of chemical reactions. There are still a lot to learn from gas-phase reactions of small molecular systems, starting from an excited state and cascading though many potential surfaces via conical intersections. Molecular dynamics using quantum mechanical energy (QM/MD) was found to be an ideal tool for study of reactions occurring far from equilibrium, such as formation of fullerenes from small carbon fragments and growth of carbon nanotubes. Challenges in theoretical studies of homogeneous catalysis are subtle ligand effects, involvement of multiple spin states and cooperative effects of multiple metal centers. Discussions here cover stories on activation of molecular nitrogen by zirconium complexes, olefin epoxidation by Salen complexes and reactions of tri-ruthenium complexes. Metalloenzymatic reactions have been discussed using protein models with ONIOM QM:MM approaches as well as active site models. Cases are presented where the enzymatic environment makes rather small effects, where it makes energetically significant effects and where it participates positively into the reaction coordinate.