Synthesis, structure, and ethylenepolymerization behavior of nickel complexes based on benzoylmethylenetri(2-alkoxylphenyl)phosphorane

Abstract

Several new nickel complexes are prepared by the treatment of the stabilized ylide benzoylmethylenetri(2-alkoxylphenyl)phosphorane with Ni(cod)₂ in the presence of PPh₃. X-Ray diffraction studies reveal that a distorted square planar geometry around Ni(II) is adopted. Upon treatment with Ni(cod)₂, the nickel complexes are sufficiently robust for ethylene polymerization. The existence of 2-alkoxyl-aryl substituents on phosphorus improves the catalytic activities. The highest activity (2.1 × 10⁶ g mol⁻¹ h⁻¹) is achieved when tri(2-isopropoxy-phenyl)phosphorane is employed (5e), which is one order higher than the corresponding SHOP catalyst. NMR analysis shows that the polyethylene mainly contains terminal double bonds and is highly linear.