Unsymmetrical α-diimine nickel (II) complex with rigid bicyclic ring ligand: Synthesis, characterization, and ethylene polymerization in the presence of AlEt2Cl

Abstract

Unsymmetrical α-diimine ligand 1 was successfully synthesized via condensation of trimethylaluminum (TMA) metalated 2-methyl-6-isopropyl-aniline with rigid bicyclic aliphatic diketone camphorquinone. Syn- and anti-stereoisomers were detected by 13C NMR in the condensation product. The corresponding α-diimine nickel (II) complex 1 was prepared from the exchange reaction of (DME)NiBr2 with the ligand 1, and displayed high activity for ethylene polymerization in the presence of diethylaluminum chloride (AlEt2Cl). The resultant polymers were confirmed by gel permeation chromatography and 13C NMR characterization to be broad molecular weight distribution polyethylene with various branches, and high degree of branching, even at low polymerization temperature −10°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008