Embodiments of the present disclosure directed towards polymerization catalysts having improved ethylene enchainment and/or improved catalyst productivity. As an example, the present disclosure provides a polymerization catalyst of Formula (I), wherein each of R
1
to R
12
is independently a C
1
to C
20
alkyl, aryl or aralkyl group, or a hydrogen, wherein at least one of R
4
to R
7
is not a hydrogen, wherein M is a Group 4 metal, and wherein, each X is independently a halide, C
1
to C
20
alkyl, aralkyl or hydrogen
本公开的实施例针对具有改善
乙烯串联和/或改善催化剂生产率的聚合催化剂。例如,本公开提供了一种
化学式(I)的聚合催化剂,其中R1至R12中的每一个独立地是C1到C20烷基、芳基或芳基烷基,或氢,其中至少有一个R4到R7不是氢,其中M是第4族
金属,且每个X独立地是卤素、C1到C20烷基、芳基烷基或氢。