ATRP of Methacrylates Catalysed by Homo- and Heterobimetallic Ruthenium Complexes

The catalytic activity of a series of ruthenium-based homo- and heterobimetallic complexes was determined by investigating the atom transfer radical polymerisation of methyl methacrylate. The complexes under investigation were [(arene)Ru(µ-Cl)3RuCl(C2H4)-(L)] (L = PCy3 or a N-heterocyclic carbene ligand), [(p-cymene)-Ru(µ-Cl)3RuCl(=C=CHR)(PCy3)] (R = Ph or t-Bu), and [RuCl2-(p-cymene){PCy2(CH2)2(eta5-C5H4)TiX2(eta5-C5H5)}] (X = Cl, F, and OBz). The catalytic activity of a variety of related [(p-cymene)-ClRu(µ-Cl)2Ru(O‚^N)(=CHPh)] complexes (O^N is a Schiff base ligand) is also reported. The results clearly demonstrate that the ligands strongly affect the ability of the resulting ruthenium complexes to favour the occurrence of a well-behaved ATRP.