Synthesis of bis(salicylaldininato)nickel complexes and their catalytic behavior for vinyl polymerization of norbornene

A series of bridged ligand 4, 4'-methylene-bis[2, 6-dialkyl-N-(2-phenylmethylene)-anil] was efficiently synthesized by the condensation reaction of 4, 4'-methylene-bis (2, 6-disubstituted aniline) and salicyl aldehyde. They easily coordinated with Ni(II) to form the title complexes, which were characterized by IR spectroscopy and elemental analysis. The complexes show good activities for vinyl polymerization of norbornene with methylalumoxane (MAO) as co-catalyst. The variations of complexes and catalytic parameters were investigated along with viscosimetric measurement of resultant polynorbornenes.