860776-07-4Relevant academic research and scientific papers
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
Tabernero, Vanessa,Cuenca, Tomas
, p. 338 - 346 (2005)
The reaction of the diamido(chloro)cyclopentadienyltitanium compounds TiCpRx[1,2-C6H4(NR′)2]Cl [CpRx = η5-C5H5, η5-C5(CH3)5, η5-C5;H4(SiMe3); R′ = CH2tBu, Pr] with the Grignard reagent MgClR (R = Me, CH 2Ph) affords the monomethyl and monobenzyl derivatives TiCp Rx[1,2-C6H4(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 TiCpRx[1,2-C6H4(NR′) 2]Cl. Instead, these reactions give the dinuclear aluminium complexes Al2[1,2-C6H4(NR′)2]Me 4 (R′ = CH2tBu, 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-C6H4(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.
