Oligomerization of α-olefins by the dimeric nickel bisamido complex [Ni{1-N(PMes 2)-2-N(μ-PMes 2)C 6H 4-κ 3N, N′, P,-κ 1P′}] 2 activated by methylalumoxane (MAO)

Abstract

The reaction of Li 2[1,2-{N(PMes 2)} 2C 6H 4], formed in situ from n-BuLi and the corresponding amines, with 1 equiv. of [NiBr 2(DME)] gives [Ni{1-N(PMes 2)-2-N(μ-PMes 2)C 6H 4-κ 3 N, N′, P-κ 1 P′}] 2 ( 1). After activation by methylalumoxane (MAO), 1 is a highly active catalyst in the oligomerization and isomerization of α-olefins such as ethene, propene, isobutene, 1-hexene and 1,5-hexadiene. For ethene oligomerization turnover frequencies (TOFs) range from 3000 to 79015 h −1, depending on the reaction conditions. The TOF for propene oligomerization reaches 1 190 730 h −1. To our knowledge, catalyst 1, activated by MAO, is the most active catalyst for the oligomerization of propene and outperforms the best known complexes for this reaction. In the reactions with 1-hexene, 1,5-hexadiene and isobutene dimerization and isomerization products were observed.