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Titanocene and Zirconocene Complexes containing Dendrimer‐Substituted Cyclopentadienyl Ligands − Synthesis and Ethylene Polymerization
Author(s) -
Andrés Román,
de Jesús Ernesto,
de la Mata F. Javier,
Flores Juan C.,
Gómez Rafael
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200209)2002:9<2281::aid-ejic2281>3.0.co;2-2
Subject(s) - chemistry , cyclopentadienyl complex , hydrosilylation , dendrimer , polymer chemistry , polymerization , ethylene , silane , zirconium , metallocene , catalysis , organometallic chemistry , polyethylene , medicinal chemistry , organic chemistry , polymer
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 (R 2 R′SiCH 2 CH 2 ) 3 SiCl [R = R′ = Et ( 1 ); R = Ph, R′ = Me ( 2 )] were prepared by hydrosilylation of chlorotrivinylsilane with R 2 R′SiH. They were reacted with K(C 5 H 5 ) and, subsequently, with KH to give K[(R 2 R′SiCH 2 CH 2 ) 3 Si(C 5 H 4 )] [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 [{(R 2 R′SiCH 2 CH 2 ) 3 SiC 5 H 4 }(C 5 R′′ 5 )TiCl 2 ] [R = R′ = Et, R′′ = H ( 5 ), R′′ = Me ( 6 ); R = Ph, R′ = Me, R′′ = H ( 7 ), R′′ = Me ( 8 )] or the symmetrically substituted metallocenes [{(Ph 2 MeSiCH 2 CH 2 ) 3 SiC 5 H 4 } 2 MCl 2 ] [M = Ti ( 9 ), Zr ( 10 )]. Cyclic voltammograms and catalytic behavior of all the new metallocenes in ethylene polymerization, using MAO as a cocatalyst, 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)