Sterically Demanding Iminopyridine Ligands

Abstract

Abstract Two sterically demanding iminopyridine ligands, (2,6‐diisopropylphenyl)[6‐(2,4,6‐triisopropylphenyl)pyridin‐2‐ylmethylene]amine and (2,6‐diisopropylphenyl)[6‐(2,6‐dimethylphenyl)pyridin‐2‐ylmethylene]amine, were prepared by a two‐step process: first, condensation of 6‐bromopyridine‐2‐carbaldehyde with an equimolecular amount of 2,6‐diisopropylaniline, and second, Kumada‐type coupling of in‐situ‐formed Grignard compounds of 1‐bromo‐2,6‐dimethylphenyl and 1‐bromo‐2,4,6‐triisopropylphenyl. Dichlorido complexes of the ligands were synthesized starting from FeCl 2 , [PdCl 2 (cod)], [NiCl 2 (dme)], and CoCl 2 (cod = 1,5‐cyclooctadiene, dme = dimethoxyethane). X‐ray crystal structure analyses of a Fe, Pd, and Co complex were determined. Ethylene polymerization/oligomerization behavior of the dichlorido complexes after activation with methylaluminoxane or triethylaluminum was studied. Ethylene dimerization selectivity greater than 95 % was observed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)