Nickel pre-catalysts bearing [(<i>N</i>)-imidoylamidine] ligands; influence of the presence of pyridine and pentafluorophenyl groups in ligand backbone on the reactivity in ethylene polymerizations
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Date
2012
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Abstract
In this contribution the synthesis and polymerization activity of the nickel complexes [NiBr2{N'-(2,6-diisopropylphenyl)-N-[1-(2,6-diisopropylphenylimine)ethyl]-N-(2,3,4,5,6-pentafluorophenyl)acetamidine}] (2), [NiBr2{N'-(2,6-diisopropylphenyl)-N-[1-(2,6-diisopropylphenylimine)ethyl]-N-(2,3,4,5,6-pentafluorophenylimine) ethylacetamidine}] (2a) and [NiBr2 {N-(2,6-diisopropylphenyl)-N-[1-(2,6-diisopropylphenylimine)]-N-(pyridin-4-yl)acetamidine}] (3)are reported. The variation of the phenyl substituents on the beta amine was found to influence the polymerization activity of the complexes. The electron withdrawing/donating capacity of the substituted ring was found to be correlated with the polymerization activity, with the pentafluoro substituted ring increasing the polymerization activity and the pyridine ring decreasing the activity. The ligands and complexes were characterized using standard techniques and the polymer properties analyzed. (C) 2011 Elsevier B. V. All rights reserved.
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Keywords
Ni polymerization catalysts, Imidoyl chloride, Late transition metal catalyst, Ethylene polymerization, Catalysts