Ruthenium benzylidene and benzylidyne complexes: Alkene metathesis catalysis

This chapter surveys the various types of ruthenium benzylidene complexes that were described in the literature within the years 1995–2021. The emphasis is placed on their synthesis, characterization, and chemical reactivity rather than their catalytic activity. Some remarkable structure/activity relationships that helped tailoring the coordination sphere of the metal center through ligand design in order to achieve the highest possible activities and selectivities toward various kinds of olefin metathesis reactions are nonetheless highlighted. A brief overview of the few ruthenium benzylidyne complexes that have been reported thus far is also included.