2-tert-Butyl and 2-phenylphenylimido complexes of titanium(IV) and their olefin polymerisation activity

摘要

Reaction of 7 equivalents of tert-butylamine with TiCl4 in hexane at 0 degreesC gave [TiCl2(NCMe3)(NH2CMe3)(2)](2) 1 which on thermalisation with 2,6-diisopropylaniline in toluene gave [TiCl2(NC6H3Pr2i-2,6)(NH2CMe3)(2)](x) 2. 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)](2) 3 and [TiCl2(NC6H4CMe3-2)(py)(2)](2) 4. 2-Phenylaniline and [TiCl2(NCMe3)(py)(3)] gave [TiCl2(NC6H4Ph-2)(py)(2)](2) 5 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)](2) 7. 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)](2) 1 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. [References: 39]