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

摘要

Unsymmetrical alpha-diimine ligand 1 was successfully, synthesized via condensation of trimethylaluminum (TMA) metalated 2-methyl-6-isopropyl-aniline with rigid bicyclic aliphatic diketone camyhorquinone. Syn- and anti-stereoisomers were detected by C-13 NMR in the condensation product. The corresponding alpha-diimine nickel (H) 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 C-13 NMR characterization to be broad molecular weight distribution polyethylene with various branches, and high degree of branching, even at low polymerization temperature -10 degrees C. (c) 2007 Wiley Periodicals, Inc.