IRC analysis of methanol carbonylation reaction catalyzed by rhodium complex

摘要

In the reaction cycle for methanol carbonylation catalyzed by Rh complex, the structure geometries of the reactant, intermediates, transition states and product of each elemental reaction have been studied by using the energy gradient method at HF/LANL2DZ level, and the changes of their potential profiles have also been calculated. Through IRC analyses of the transition states for each elemental reaction, it is confirmed that the various structure geometries obtained are stationary points on the cycle reaction pathway of methanol carbonylation catalyzed by Rh complex, and the changes are given in energies and structure geometries of the reactant molecules along the reaction pathway of lowest energy. It has been proposed that the geometrical conversions of intermediates play an important role during the cycle reaction. Through analyses of structure geometries, it has been suggested that, in addition to cis- and trans-structure exchange linkage of catalysis reactive species, the two pathways, cis- and trans-catalyzed cycle reactions, can also be linked through geometrical conversion of intermediates, of which the activation energy is 49.79 kJ/mol. Moreover, the reductive elimination elemental reaction may be neither c/s-cycle nor trans- one, showing that the cycle reaction can be achieved through various pathways. However different the pathway, the oxidative addition elemental reaction of CH_3I is the rate-controlling step.