New Half-Sandwich Chromium(III) Complexes Bearing Phenoxy-Phosphine (Oxide) [O,P(═O)] Ligands: Synthesis, Structures, and Catalytic Properties for Ethylene (Co)Polymerization
作者:Ping Tao、Hong-Liang Mu、Jing-Yu Liu、Yue-Sheng Li
DOI:10.1021/om400517t
日期:2013.9.9
A series of novel half-sandwich-type chromium complexes bearing phenoxy-phosphine [O,P] ligands (3a–3f) or phenoxy-phosphine oxide [O,P═O] ligands (4b–4e) were synthesized in high yields from CpCrCl2(thf) with corresponding ligands in THF. X-ray structure analyses for 3b, 3c, 3e, and 4c revealed that these complexes adopt a three-legged piano stool geometry. When activated by modified methylaluminoxane
一系列新型的由苯氧膦[O,P]配体(3a - 3f)或苯氧膦氧化[O,P═O]配体(4b - 4e)组成的新型半三明治型铬配合物从具有相应配体的CpCrCl 2(thf)在THF中。对3b,3c,3e和4c的X射线结构分析表明,这些复合体采用三足钢琴凳几何形状。当被改性的甲基铝氧烷活化时,配合物3a – 3f对乙烯聚合显示出中等至高的活性,从而得到具有单峰分子量分布的高分子量聚合物。令人兴奋的是,配合物3c可以有效地促进乙烯/ NBE的共聚,因此,可以在优化的条件下轻松获得具有高NBE含量的高分子量共聚物。[O,P═O]配合物显示出比[O,P]类似物更高的催化活性,但产生的分子量要低得多。聚合行为的差异可能是由空间体积的变化和金属中心周围的电子效应引起的。