Synthesis and Characterization of α-Diimine Nickel (II) Catalyst Containing Br Groups for Ethylene Polymerization

A new Br-substituted alpha-diimine compound and its corresponding Ni (II) complex, {bis[ N,N'-(3-bromo-2, 4, 6-trimethylphenyl) imino] acenaphthene} dibromonickel, were successfully synthesized and characterized by (1)H NMR, (13)C NMR, elemental analysis, FTIR and XPS. The pre-catalyst 2 activated by methylaluminoxane(MAO) was tested in the polymerization of ethylene. The results show that the catalyst exhibits highly activity[55 g PE/(mol Ni . h . Pa)]. The catalyst system 2/MAO shows the highest activity with the 800 of Al/Ni molar ratio at 25 degrees C It is found that the catalyst containing electron-withdrawing groups Br shows better thermal stability and almost the same catalytic activity as the one without groups Br. At the same time, branching degree is increased in the presence of electron-withdrawing groups Br.