A computational study of structures and catalytic activities of Hoveyda-Grubbs analogues bearing coumarin or isopropoxycoumarin moiety

Abstract The DFT/M06-D3 method was used to investigate structures and activation free energies for a series of Hoveyda-Grubbs-like catalysts with the isopropoxybenzene part replaced by coumarin (2H-chromen-2-one) and ten derivatives of isopropoxycoumarin. Out of ten investigated isopropoxycoumarin derivatives two show free enthalpies of initiation around 3–5 kcal/mol lower than the Hoveyda-Grubbs catalyst and free enthalpies of the catalytic cycle around 2–3 kcal/mol lower than the Hoveyda-Grubbs suggesting fast initiation. Additionally, correlations between the initiation free enthalpies and ruthenium-oxygen bond strengths as well as natural partial charges on carbene carbon atom have been found, described and rationalized.