New Nickel Ethylene Oligomerization Catalysts Bearing Bidentate <i>P</i>,<i>N</i>-Phosphinopyridine Ligands with Different Substituents α to Phosphorus
作者:Fredy Speiser、Pierre Braunstein、Lucien Saussine
DOI:10.1021/om034198i
日期:2004.5.1
Ni·h was observed for 11 in the presence of 800 equiv of MAO. The selectivities were in the range 70−85% for the C4 olefins and in the range 33−38% for 1-butene within the C4 fraction. For these P,N ligands, increasing the degree of alkyl substitution at the carbon α to P leads to higher activities for ethylene oligomerization and more selective formation of α-olefins. The nature of the N-heterocycle
新配体phosphinopyridine外消旋2 - [(二苯基膦基)苄基]吡啶(6),外消旋-2- [1 ' - (二苯基膦基)乙基]吡啶(7),和2- [1' - (二苯基膦基)-1'甲基〕乙基吡啶(8),在所述α碳为P变量替换被用于顺磁性的Ni(II)配合物[氯化镍的合成2(P,N)] 9 - 11分别。配合物11 ·0.5CH 2 Cl 2X射线衍射表明,尽管通过Evans方法确定溶液中所有配合物的配位球均是扭曲的四面体,但该金属在金属上几乎具有平面配位几何形状。在仅6当量的AlEtCl 2存在下,Ni络合物为乙烯催化低聚反应提供了活性,最高可达58 100 mol C 2 H 4 / mol Ni·h(11)。在存在2当量的AlEtCl 2的情况下,对于9而言,C 4烯烃的选择性达到81%,而对1-丁烯的选择性仅为11-14%。在存在400或800当量的甲基铝氧烷(MAO)的情况下,配合物9