Nickel(II) complexes of bidentate N-N′ ligands containing mixed pyrazole, pyrimidine and pyridine aromatic rings as catalysts for ethylene polymerisation

The new complexes [NiBr2(pzpm)] (1), [NiBr2(4-Mepzpm)] (2) and [NiBr2(4-Brpzpm)] (3), behave as catalysts for the polymerisation of ethylene, in the presence methylaluminoxane (MAO). Low molecular weight branched polyethylene products were obtained with Mn values ranging from ca. 550 and 1500 g mol−1 and unusually low dispersities of 1.2-1.7.