Isocyanide complexes of nickel, NiBr2(CNAr)2, are found to be active catalysts for polymerization of ethylene in the presence of methylaluminoxane (MAO). The catalytic activity and properties of polyethylene formed vary with substituents on the aryl group, in particular, at the 2- or 2,6-positions. The nickel complexes having 2,6-diphenylphenylisocyanide and its analogues are catalysts showing moderate activity and giving high molecular weight polyethylene (M v > 106), whereas those bearing 2-phenylphenylisocyanide and its analogues give polyethylene with M w = 103−104.

The azanickellacyclic complex (1) produced by trimerization of an isocyanide on the nickel atom is found to be a new ethylene polymerization catalyst; catalytic activity is increased by incorporation of the second metal to a diimino moiety of 1 leading to formation of heterobimetallic complexes.

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