2-tert-Butyl and 2-phenylphenylimido complexes of titanium(IV) and their olefin polymerisation activity
- 15 January 2001
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 3,p. 232-239
- https://doi.org/10.1039/b008232p
Abstract
Reaction of 7 equivalents of tert-butylamine with TiCl4 in hexane at 0 °C gave [TiCl2(NCMe3)(NH2CMe3)2]21 which on thermalisation with 2,6-diisopropylaniline in toluene gave [TiCl2(NC6H3Pri 2-2,6)(NH2CMe3)2]x2. Imido exchange of [TiCl2(NCMe3)(NH2CMe3)]x with o-toluidine or 2-tert-butylaniline and addition of pyridine gave [TiCl2(NC6H4Me-2)(py)3] and [TiCl2(NC6H4CMe3-2)(py)3] which crystallised to give [TiCl2(NC6H4Me-2)(py)2]23 and [TiCl2(NC6H4CMe3-2)(py)2]24. 2-Phenylaniline and [TiCl2(NCMe3)(py)3] gave [TiCl2(NC6H4Ph-2)(py)2]25 on crystallisation and reaction of tert-butylaniline or 2-phenylaniline with [TiCl2(NCMe3)(tmeda)] gave [TiCl2(NC6H4CMe3-2)(tmeda)] 6 and [TiCl2(NC6H4Ph-2)(tmeda)]27. Complexes 1, 3, 4, 5, 6, and 7 were characterised by X-ray crystallography and the possibility of imdo ligand C–N bond rotation taking place analysed and compared with the NMR spectra. [TiCl2(NCMe3)(tmeda)] and MAO·(MeAlO)n, polymerises ethylene at low pressure with low activity (3.2 g mmol−1 h−1 bar−1), [TiCl2(NC6H4CMe3)(tmeda)] or [TiCl2(NC6H4Ph-2)(tmeda)] and MAO gives a 4-fold increase in activity whereas propene is not polymerised but 1-hexene is. Heterogenisation by addition of [TiCl2(NCMe3)(NH2CMe3)2]21 to tmeda-functionalised crosslinked polystyrene or imido exchange of [TiCl2(NCMe3)(tmeda)] with NH2-functionalised crosslinked polystyrene gives supported complexes which do not polymerise ethylene at low pressure in the presence of MAO.Keywords
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