Ethylene oligomerization by hydrazone Ni(II) complexes/MAO Original Research Article

The ethylene oligomerization was investigated by using new hydrazone nickel complexes Ni(N∧O)2Cl2 (2a, N^O=4,5-diazafluorene-9-one-benzoylhydrazone; 2b, N^O=4,5-diazafluorene-9-one-4-nitrobenzoylhydrazone; 2c, N^O=4,5-diazafluorene-9-one-3-nitrobenzoylhydrazone) with methylaluminoxane (MAO) in toluene. Those catalytic systems mainly assisted the dimerization of ethylene with good catalytic activity (105 to 104 g mol−1 h−1) at ambient pressure. The reaction conditions, such as the ratios of Al/Ni, reaction temperature and reaction time, were investigated. The best catalytic activity for the three complexes was observed for complex 2a without nitro-substituent on its aryl ring.