Preparation of a well-defined silica-supported nickel-diimine alkyl complex - application for the gas-phase polymerization of ethylene

Abstract

The interaction of [(Α-diimine)Ni(CH2SiMe3)2] (1) (α-diimine = 2,3-dimethyl-l,4-[(2,6)-diisopro-pylphenyl]-N,N -diazadiene) with the silanol =Si - OH groups of Aerosil Si02-(700) leads to the formation of the surface complex [≡SiO - Ni(a-diimine) (CH2SiMe3)] (2) with the concomitant emission of 1 mol equiv of SiMe4 (TMS). The surface complex characterized by IR, chemical and mass balance analyses, solid-state NMR, and EXAFS has been activated by gaseous BF3 to give an active gas-phase ethylene polymerization catalyst. The polymers thus obtained present a highly branched structure. The activity is attributed to the formation of the putative surface ion pair [≡SiOBF3]-[Ni(7alpha;-diimine)(CH 2SiMe3)]+. © 2009 American Chemical Society.