Novel dendrimer-based nickel catalyst: synthesis,characterization and performance in ethylene oligomerization

A novel nickel metallodendrimer was synthesized with poly(amidoamine), 3,5-di-tert-butyl-2-hydroxy-benzaldehyde and nickel chloride via the Schiff’s base and the complexation reactions. Structures of the dendritic ligand and its nickel complex were characterized by IR, NMR, UV, ESI-MS and elemental analyses. This new nickel metallodendrimer as a catalyst precursor, together with methylaluminoxane as an activator, was evaluated in the ethylene oligomerization. Under the conditions of 0.5 h, 0.5 MPa, 25°C and Al/Ni mole ratio 500: 1 employed for the nickel complex, the catalytic activity showed a maximum value of 4.93 × 10⁵ grams per mole of Ni catalyst per hour. Substituents on the benzene ring seem to have a negative influence on the catalytic activity of the complex.