484065-86-3Relevant articles and documents
Titanocene and zirconocene complexes containing dendrimer-substituted cyclopentadienyl ligands - Synthesis and ethylene polymerization
Andres, Roman,De Jesus, Ernesto,De La Mata, F. Javier,Flores, Juan C.,Gomez, Rafael
, p. 2281 - 2286 (2007/10/03)
This paper describes the synthesis of a series of titanium and zirconium metallocenes bearing one or two first-generation silane dendritic wedges as bulky substituents at their cyclopentadienyl rings. Wedges (R2R′SiCH2CH2)3SiCl [R = R′ = Et (1); R = Ph, R′ = Me (2)] were prepared by hydrosilylation of chlorotrivinylsilane with R2R′SiH. They were reacted with K(C5H5 and, subsequently, with KH to give K[(R2R′SiCH2 CH2)3Si(C5H4)] [R = R′ = Et (3); R = Ph, R′ = Me (4)]. The dendronized cyclopentadienides 3 and 4 were the starting materials for preparation of the mixed-ring titanocenes [{(R2R′SiCH2 CH2)3SiC5H4} (C5R″5)TiCl2] [R = R′ = Et, R″ = H (5), R″ = Me (6); R = Ph, R′ = Me, R″ = H (7), R″ = Me (8)] or the symmetrically substituted metallocenes [{(Ph2MeSiCH2 CH2)3SiC5 H4}2MCl2] [M = Ti (9), Zr (10)]. Cyclic voltammograms and catalytic behavior of all the new metallocenes in ethylene polymerization, using MAO as a co-catalyst, have been studied and compared to that of related non-dendritic complexes. Polyethylene polydispersities increase with the number of dendritic wedges in the catalyst, while activities decrease. Bimodal molecular weight distributions were clearly observed for the bis-dendritic titanocene 9. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
