A computational study of Grubbs-type catalysts: Structure and application in the degenerate metathesis of ethylene

The ground-state geometries of the first-generation Grubbs pre-catalyst and its active monophosphine derivative have been explored at the molecular mechanics (MM), semi-empirical (SE) and density functional (DFT) levels; the theoretical data for the pre-catalyst have also been compared with the corresponding dimensions of known crystalline analogues. DFT studies of the ligand-dissociation energies for the first- and second-generation Grubbs pre-catalysts and the degenerate metathesis of ethylene using a truncated model of the first-generation catalyst have been undertaken and the results compared with available data. Transition states have been located for each step of the metathesis reaction and the calculated free energies of activation afford new insights into the rate-determining processes.