We report the immobilization of the ultrarigid ansa-hafnocene complexes rac-[Me₂Si(Ind*)₂HfCl₂] (rac-1; Ind* = 7-(3′,5′-Di-tert-butylphenyl)-4-methoxy-2-methylindenyl) on silica as hetereogeneous catalysts for propene polymerization. A sequential three-step synthesis on the siliceous surface led to pre-catalysts of the generalized structure SiO₂–Si(Ind*)₂HfCl₂, which possess the silylene bridge of the substituted bis(indenyl) ligand directly attached to the surface. The immobilized pre-catalysts show very poor performance in the polymerization of propene, independent on the reaction conditions and the employed silica. Based on the results, we suggest that the close proximity of the catalyst to the surface combined with the steric congestion provoked by the ligand prevents a continuous polymerization, most likely due to a blockage of the catalytically active sites with growing polymer.

我们报告的ultrarigid的固定柄-hafnocene络合物外消旋- [我₂的Si（茚*）₂的HfCl ₂ ]（外消旋- 1 ;工业* = 7-（3'，5'-二-叔丁基苯基）-4- （-甲氧基-2-甲基茚基）在二氧化硅上作为丙烯聚合的非均相催化剂。在硅质表面上进行连续的三步合成，生成了具有广义结构SiO ₂ -Si（Ind *）₂ HfCl _2的预催化剂，其具有直接连接到表面的取代双（茚基）配体的亚甲硅烷基桥。固定的预催化剂在丙烯的聚合反应中表现出非常差的性能，与反应条件和所用的二氧化硅无关。根据这些结果，我们认为催化剂与表面的紧密结合以及配体引起的空间拥堵阻止了连续聚合，这很可能是由于生长中的聚合物阻塞了催化活性位。