Synthesis of palladium(II) pyridyl acylhydrazone complexes and application to homo- and copolymerization of cyclic olefins

A series of new palladium(II)/pyridyl acylhydrazone complexes were synthesized through the reaction of PdBr2(NCMe)2 and pyridyl acylhydrazone. The X-ray crystallographic analysis revealed that the palladium center is coordinated by two bromide atoms and two nitrogen atoms of pyridyl acylhydrazone ligand. This coordination mode of pyridyl acylhydrazone ligand forms a striking contrast to the corresponding nikel(II)/pyridyl acylhydrazone complexes. These new palladium complexes showed high catalytic activity for homopolymerization of cyclic olefins such as norbornene and tetracyclododecene, and for copolymerization of tetracyclododecene with norbornene in the presence of MAO.