Probing the Mechanism of Olefin Metathesis in Grubbs–Hoveyda and Grela Type Complexes

The more the better: Kinetic data derived from UV/Vis spectroscopy (see picture) provide conclusive evidence for participation of the olefinic substrate in the rate-limiting step of the initiation reaction of Grubbs–Hoveyda type olefin metathesis catalysts, and for a second olefin-independent step, which is rate-limiting only at very high olefin concentrations.