Ethylene polymerization behavior of monometallic complexes and metallodendrimers based on cyclopentadienyl-aryloxy titanium units

Titanium-containing carbosilane dendrimers of type nG-Si[(CH2)3[{C6H4 − y(OMe)y}O]Ti(C5H5)Cl2]x, in which phenoxy group is anchored to the dendritic skeleton in para position through eugenol or 2-allyl-2,6-dimethoxyphenol precursors, were used in ethylene polymerization. Fresh toluene solutions of these dendrimers in conjunction with MAO behaved as moderate active systems. However, their aged toluene solutions, when they were activated with MAO became highly active catalysts as result of dendrimer aggregation processes. However, when the peripheral unit are replaced by [Ti(C5Me5)Cl2] or [M(C5H5)2Cl] groups or 2-allyl-6-methylphenol are incorporated to the peryphery of a carbosilane dendrimer no aggregation was observed upon aging.

Graphical abstractMonometallic complexes and titanium-containing carbosilane dendrimers of type nG-Si[(CH2)3[{C6H4 − y(OMe)y}O]Ti(C5H5)Cl2]x were used in ethylene polymerization. Fresh toluene solutions of these dendrimers in conjunction with MAO behaved as moderate active systems. However, in the case of complexes in which the phenoxy group is attached to the dendrimer in para position, their aged toluene solutions, when they were activated with MAO, became highly active catalysts as result of dendrimer aggregation processes.Figure optionsDownload full-size imageDownload as PowerPoint slide