title: Controlled/Living Radical Polymerization. From Synthesis to Materials series: ACS Symposium Series editor: Krysztof Matyjaszewski publisher: American Chemical Society city: Washington, DC year: 2006 volume: 944 first page: 40 last page: 55 isbn: 0-8412-3991-6 doi: 10.1021/bk-2006-0944.ch004
Abstract: The relative catalytic activities of a series of ruthenium-based complexes of the general formula [RuCl2(p-cymene)(NHC)], [RuCl2(=CHPh)(PR3)(NHC)], and [RuCl2(=CHPh)(NHC)2] (NHC is a N-heterocyclic carbene ligand) were determined by investigating the atom transfer radical polymerization (ATRP) of methyl methacrylate and styrene. The catalytic activity of a variety of related [RuCl(O^N)(=CHR)(NHC)] complexes and of their cationic counterparts, [Ru(O^N)(=CHR)(NHC)]+ BF4- (R = Ph or OEt, O^N is a Schiff base ligand), is also reported. The results clearly demonstrate that, with both methyl methacrylate and styrene, subtle modifications of the substituents of the NHC ligand lead to dramatic changes in the ability of the resulting ruthenium complexes to favor the occurrence of a well-behaved ATRP.