Stable ruthenium indenylidene complexes with a sterically reduced NHC ligand

Stable and active Ru olefin metathesis catalyst 7 bearing a sterically reduced NHC ligand was synthesized. Upon action of pyridine, 7 forms complex 24, the first example of an Ru–indenylidene catalyst bearing a labile pyridine ligand and a sterically less demanding NHC ligand.