Dimerization of propylene by bis(β-ketiminate) nickel(II) and cobalt(II) catalysts in the presence of organoaluminum activator and phosphine ligand

Abstract

A preliminary study of the catalytic behavior of bis(β-ketiminate) nickel(II) and cobalt(II) complexes in the dimerization of propylene was undertaken in combination with organoaluminum co-catalyst and ancillary phosphine ligand. The effects of type and relative amounts of aluminum co-catalyst as well as the nature of nickel and cobalt precatalysts were investigated. The results showed that the presence of ancillary phosphine ligand deeply modified the activity and selectivity of catalytic system, especially at the reaction temperature below 0 °C. An extremely high turnover frequency up to 268,000 h −1 and a rather high selectivity to dimers (95.6%) by the bis( N-(2,6-dimethylphenyl)-4-aminopent-3-en-2-ono) nickel(II) complex ( 1c) in the presence of Et 3Al 2Cl 3 and PCy 3 was achieved in the propylene dimerization under appropriate reaction conditions.