Vinyl addition polymerization of norbornene catalyzed by β-iminoamine Ni(II) complexes/methylaluminoxane systems

Two nickel(II) complexes (A and B) bearing beta-iminoamine ligands, [2-(ArN=CH)-C(6)H(4)-NMe(2)] (La, Ar = 2,6-i-Pr(2)C(6)H(3); Lb, Ar = 2,6-Me(2)C(6)H(3)), were synthesized and characterized by elemental analyses and (1)H NMR. X-ray crystal structure of complex B reveals that the six-membered chelate ring adopts a envelope conformation, with nickel(II) atom deviating from the plane of backbone aromatic ring by 1.164 angstrom. In the presence of methylaluminoxane (MAO), both complexes showed moderate activities of 10(5) g mol(Ni)(-1) h(-1) for norbornene polymerization. beta-iminoamine Ni(II)/MAO catalysts gave unimodal polymers (M(w), 3.16-8.02 x 10(5) g/mol) with a relatively narrow MWD (M(w)/M(n), 1.59-2.14), indicative of single-site catalyst behavior. The obtained polymers are vinyl-type polynorbornenes (PNBs), which are soluble in common solvents such as toluene, cyclohexane and dichlorobenzene. (C) 2011 Elsevier B.V. All rights reserved.