A series of silsesquioxane-supported Phillips-type molecular catalysts for ethylene polymerization were synthesized by introducing various functional groups in proximity to monoalkylated Cr(III). They were moderately active in ethylene polymerization, while the performance was sensitive to the type of functional group. In particular, the presence of a lone pair near the active center was found to enhance
Ethylenepolymerization catalyst prepared by grafting Cr[CH(SiMe3)2]3 on SiO2 contains well-defined Cr(III) alkyl surface sites, as shown using a combination of ML-supported-XAS and EPR spectroscopies. Furthermore, it is also possible to show by EPR that Cr(III) alkyl sites are competent for olefin insertion.
通过将 Cr[CH(SiMe 3 ) 2 ] 3接枝到 SiO 2上制备的乙烯聚合催化剂含有明确的 Cr(III) 烷基表面位点,如使用 ML 负载的 XAS 和 EPR 光谱的组合所示。此外,还可以通过EPR表明Cr(III)烷基位点能够进行烯烃插入。