Catalytic dimerization of ethylene to 1-butene by square-planar nickel complexes

Abstract

The dimerization of ethylene by [NiBr(2,4,6-Me3C6H2)P2] (PPEt3, PMe2Ph, PPh3, P(Bu)3, P(i-Bu)3, PCy3, and PBz3 (Bzbenzyl)) and [Ni(2,4,6-Me3C6H2)(NCMe)P2]BF4 (PPEt3, PMe2Ph, P(Bu)3, P(i-Bu)3, and PBz3) in THF solution has been investigated. With ionic compounds, only butenes are formed with very high selectivity to 1-butene (90%). Activity increases with the basicity and size of the phosphine ligands. Ionic compounds are always more active than the neutral precursors for the same phosphine. The ionic compound [Ni(2,4,6-Me3C6H2)(NCMe)(PBz3)2]BF4 shows the highest turnover rate (0.7 s-1). © 1991.