Evaluation of ruthenium-based complexes for the controlled radical polymerization of vinyl monomers

Abstract

New complexes of the type RuCl 2 (p-cymene)L where the ligand L is either a phosphine or a stable triazolinylidene carbene have been tested and compared to the Grubbs' benzylidene complex RuCl 2 (=CHPh)(PCy 3 ) 2 as catalyst precursors for the controlled atom transfer radical polymerization (ATRP) of methyl methacrylate and of various para-substituted styrenes. Kinetic data and Hammett ρ constants are reported, as well as the X-ray structure of the ortho-metallated triazolinylidene-ruthenium(II) complex RuCl(p-cymene)[1,2-phenylene[3,4-diphenyl-1H-1,2,4-triazol-1-yl-5(4H)-ylidene]].Key words: ruthenium, carbene, chelate complex, homogeneous catalysis, atom transfer radical polymerization.