Dual activity of ruthenium catalysts in controlled radical reactions and olefin metathesis

The catalytic activity of five ruthenium-arene complexes of the RuCl2(p-cymene)L type was
investigated in controlled radical reactions and olefin metathesis. The ligands L were stable Nheterocyclic carbenes (NHCs) derived from imidazol-2-ylidene. They differed by the nature of
the substituents on the nitrogen atoms (R1) and on the carbon-carbon double bond (R2) of the
heterocyclic ring. Thus, R1 was either the mesityl or the cyclohexyl group, and R2 included
methyl, hydrogen, or chloro substituents.The complexes were tested as initiators for the Atom Transfer Radical Addition (ATRA) of carbon tetrachloride to methyl methacrylate and styrene, for the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate and styrene, and for the Ring-Opening Metathesis Polymerization (ROMP) of cyclooctene. Some species displayed a dual activity and promoted both olefin metathesis and ATRP.