of the corresponding catalysts based on bidentate phenoxy‐phosphine ligands. Both the coordinated donors and the ortho‐substituent of the ligands played an important role in improving catalytic activity. The effects of reaction parameters, such as cocatalyst and Al/Cr molar ratio as well as reaction temperature, on ethylene polymerization behaviors were investigated in detail for two favorable catalytic
基于二齿
苯氧基膦酰基新颖
铬催化剂(HO-2R 1 -4R 2 -6(PH 2 PO)C 6 H ^ 2,R 1 = R 2 = H,3A ; R 1 =吨卜,R 2 = H,图3b ; R 1 = R 2 =吨卜,3c中; R 1 = R 2 =
异丙苯,3D ; R 1 =
蒽,R 2 = H,3E)和
苯硫酚膦(HS-2R 1 -4R 2-6(Ph 2 P)C 6 H 2:R 1 = R 2 = H,4a ; 制备并表征R 1= SiMe 3,R 2= H,4b)。用改性的
甲基铝氧烷处理后,这些
催化剂对
乙烯聚合反应显示出中等至高催化活性。它们的活性高于相应的基于双齿
苯氧基
膦配体的
催化剂。既有协调的捐助者,也有正统的
配体的取代基在提高催化活性方面起着重要作用。对于两种有利的催化体系3b / CrCl 3(thf)3和4b / CrCl 3(thf ),详细研究了反应参数(例如助
催化剂和Al /