209798-23-2Relevant academic research and scientific papers
Nickel phenyl complexes with chela ting K2-P,O ligands as catalysts for the oligomerization of ethylene into linear α-olefins
Pietsch, Joerg,Braunstein, Pierre,Chauvin, Yves
, p. 467 - 472 (2008/10/08)
Starting from [Ni(COD)2] and the phosphorus ylide Ph3P(o-C6H4O), the complexes [NiPh{Ph2P(o-C6H4O)}-(PR3)] [PR3 = PMe3 (2a), PMe2Ph (2b), PMePh2 (2c), PCy3 (2d), PPh3 (2e), PTol3 (2f), P(p-C6H4OMe)3 (2g), P(OMe)3 (2h), P(p-C6H4Cl)3 (2i), P(p-C6H4F)3 (2j), P(p-C6H4CF3)3 (2k)] were synthesized in the presence of the corresponding phosphine. The bis-chelate complex cis-[Ni{Ph2P(o-C6H4O)}2] (3) was formed as a minor by-product during these reactions, but was the only isolable compound when the reactions were conducted at temperatures above 60°C. Oxidative addition of a P-Ph bond to the Ni0 centre was also used to synthesize [NiPh{Ph2PCH...C(...O)Ph}(PMe3)] (1a) from the α-ketophosphorus ylide Ph3P=CHC(=O)Ph and PMe3. Reaction of [Ph3P(o-C6H4NH2)]Br with [Ni(COD)2] and PTol3 yielded the expected compound [NiPh{Ph2P(o-C6H4NH)}(PTol3)] (6) via deprotonation of the NH2 function by an excess of PTol3. Experiments to study the potential of these nickel complexes as catalysts for ethylene oligomerization into linear α-olefins (> 95%) showed widely varying activities [500-180000 mol C2H4 (mol catalyst h)-1] and mass distributions of the α-olefins. In contrast to the nickel phosphino enolate complexes of the type [NiPh{Ph2PCH...C(...O)Ph}(PR3)] [PR3 = PMe3 (1a), PCy3 (1b), PPh3 (1c)], the corresponding nickel phosphino phenolates [NiPh{Ph2P(o-C6H4O)}(PR3)] (2) generally showed a marked tendency to oligomerize ethylene into α-olefins of higher molecular weight: C4= to C30= for 1 versus C4= to C90= for 2. The complex [NiPh{Ph2P(o-C6H4NH)}(PTol3)] (6), on the other hand, showed no activity for ethylene oligomerization.
