A catalyst precursor of the formula: ##STR1## wherein: L is a cycloalkadienyl ligand; W, X, Y, and Z are independently hydrogen, a hydrocarbyl group containing 1 to 20 carbon atoms, or a silyl group, and may be connected to L through a bridging group comprising at least two Group IVA atoms; with the proviso that one of X, Y, and Z is a negative charge stabilizing group selected from the group consisting of Group IVA trialkyl groups, aryl groups, heteroaromatic groups, ethylenically unsaturated hydrocarbon groups, acetylenically unsaturated hydrocarbon groups, ketonic groups, and aromatic organometallic moieties, is provided. When combined with a compound comprising a metal from Groups IIIB to VIII or the Lanthanide series of the Periodic Table of elements and an activating cocatalyst, the catalyst precursor is useful for the polymerization of olefins.
一种催化剂前体的
化学式:##STR1## 其中:L是环烯二烯基
配体;W、X、Y和Z分别独立地表示氢、含1至20个碳原子的碳氢基团或
硅基团,并可以通过至少包含两个IVA族元素的桥接基团与L相连;但X、Y和Z中的一个是负电荷稳定基团,所述负电荷稳定基团选自IVA族三烷基基团、芳基团、杂环芳基团、
乙烯基不饱和碳氢基团、
乙炔基不饱和碳氢基团、酮基团和芳香族
金属有机基团。当与来自元素周期表IIIB到VIII族或
镧系
金属的化合物以及活性协同催化剂结合时,该催化剂前体可用于烯烃的聚合。