Ethylene oligomerization by cobalt(II) diimine complexes/EAO

The catalytic properties of a series of Co(II) diimine complexes Co(N<^>N)C l-2 (A: N<^>N = N,N'-o-phenylenebisbenzal; B: N<^>N = N,N'-ethylenebisbenza l; C: N<^>N = N,N'-o-phenylenebis(diphenylmethylene)) in combination with e thylaluminoxane (EAO) as cocatalyst for ethylene oligomerization have been investigated. Treatment of the cobalt(II) diimine complexes with EAO in tol uene generated active catalysts in situ that are capable of oligomerizing e thylene to low-carbon olefins. The catalytic activity and product distribut ion were affected by reaction conditions, such as reaction temperature, the ratios of Al/Co and the reaction time. The activity of 1.30 x 10(5) g olig omers/mol Co h for the catalytic system of CoCl2(Ph2C=o-NC6H4N=CPh2) with E AO at 200 degreesC was observed, with the selectivity of 94.4% to C4-10 ole fins and 87.2% to C4-10 linear alpha -olefins. (C) 2001 Elsevier Science B. V. All rights reserved.