The Alkene Metathesis Ruthenium Catalyst Saga

The history of the alkene metathesis ruthenium catalyst discovery is presented and illustrated with catalyst precursor preparation methods and with references to applications in fine chemistry and polymerisation. These precursors involve well-defined and in situ prepared rutheniumalkylidenes, -vinylidenes and -allenylidenes containing bulky electronrich phosphine or imidazolylidene and imidazolinylidene ligands.