An Efficient Keim-Type Catalyst Based on an Electron-Poor P,O-Chelate; Tuning the Selectivity of Ethylene Oligomerisation towards Short α-Olefins
✍ Scribed by Pierre Kuhn; David Sémeril; Catherine Jeunesse; Dominique Matt; Pierre Lutz; Richard Welter
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 129 KB
- Volume
- 2005
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
The tertiary phosphane Ph~2~P‐pzONa, in which the phosphorus atom is substituted by an electron‐withdrawing pyrazol‐onato unit, reacts with trans‐[NiPhCl(PPh~3~)~2~] to afford quan‐titatively trans‐P,P'‐[NiPh(Ph~2~P‐pzO)(PPh~3~)] (4), the first Keim‐type catalyst derived from an amide. In the absence of any cocatalyst, complex 4 converts ethylene in high selectivity and activity into α‐olefins. The product distribution is drastically shifted towards lower oligomers when compared to the outcome of the reaction carried out with the conventional SHOP catalyst. Thus, when operating at 1 bar, over 99 wt.‐% of the oligomers formed are C~4~–C~16~ oligomers. In ethylene‐free solvents, 4 was shown to slowly undergo reductive elimination to produce the stabilised phosphorus ylide Ph~3~P‐pzO (5). Both compounds (4 and 5) were characterised by single‐crystal X‐ray diffraction analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)