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Studies of the Nature of the Catalytic Species in the α‐Olefin Polymerisation Processes Generated by the Reaction of Diamido(cyclopentadienyl)titanium Complexes with Aluminium Reagents as Cocatalysts
Author(s) -
Tabernero Vanessa,
Cuenca Tomás
Publication year - 2005
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/ejic.200400661
Subject(s) - chemistry , methylaluminoxane , medicinal chemistry , catalysis , cyclopentadienyl complex , ethylene , reagent , polymerization , organometallic chemistry , styrene , ligand (biochemistry) , olefin fiber , polymer chemistry , organic chemistry , metallocene , copolymer , biochemistry , receptor , polymer
The reaction of the diamido(chloro)cyclopentadienyltitanium compounds TiCp Rx [1,2‐C 6 H 4 (NR′) 2 ]Cl [Cp Rx = η 5 ‐C 5 H 5 , η 5 ‐C 5 (CH 3 ) 5 , η 5 ‐C 5 H 4 (SiMe 3 ); R′ = CH 2 t Bu, Pr] with the Grignard reagent MgClR (R = Me, CH 2 Ph) affords the monomethyl and monobenzyl derivatives TiCp Rx [1,2‐C 6 H 4 (NR′) 2 ]R. Upon addition of methylaluminoxane (MAO), the chloro‐ and alkyltitanium complexes show low activity towards the polymerisation of ethylene and styrene. However, no methylation was observed during the treatment of trimethylaluminium with the chloro compounds TiCp Rx [1,2‐C 6 H 4 (NR′) 2 ]Cl. Instead, these reactions give the dinuclear aluminium complexes Al 2 [1,2‐C 6 H 4 (NR′) 2 ]Me 4 (R′ = CH 2 t Bu, Pr) through transmetallation of the diamido ligand, suggesting a deactivation process of the catalysts in the olefin polymerisation reactions. In an additional effort to model the catalytic species, stoichiometric reactions between the methyl derivatives TiCp Rx [1,2‐C 6 H 4 (NR′) 2 ]Me and solid methylaluminoxane (MAO) were studied by NMR spectroscopy. Monitoring of these reactions revealed the formation of zwitterionic species depending on the nature of the solvent. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)