Abstract
The interaction of [(alpha-diimine)Ni(CH2SiMe3)(2)] (1) (alpha-diimine = 2,3-dimethyl-1,4-[(2',6')-diisopropylphenyl]-N,N'-diazadiene) with the silanol Si-OH groups of Aerosil SiO2-(700) leads to the formation of the surface complex [ SiO-Ni(alpha-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(alpha-diimine)(CH2SiMe3)](+).