Ru-dimethyl sulfoxide complexes as catalysts precursors for ROMP of norbornene and ATRP of methyl methacrylate

Abstract

The catalytic activity of the five-coordinated [RuCl2(PPh3)(S-dmso)2] complex was investigated for ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Syntheses via ROMP of polyNBE were dependent on the ethyl diazoacetate (EDA) amount, used as starting carbene source, monomer concentration, temperature, and reaction time. The best polyNBE yields were obtained at 50°C for 120min with [NBE]/[Ru]=5000 in presence of 5μL of EDA. MMA polymerization via ATRP was conducted as a function of time with different ethyl 2-bromoisobutyrate initiator and monomer concentrations. The kinetic data for ATRP show linear increase between MMA conversion and molecular weight. Kinetic studies with the six-coordinated [RuCl2(S-dmso)3(O-dmso)] complex also showed an increase in the molecular weight with conversion, but with a marked deviation from theoretical molecular weights. This is consistent with the better control in the polymerization supported by electronic and steric properties of the PPh3 ligand in the title complex