Reactive intermediates in living olefin polymerization over homogeneous catalysts based on bis[N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato]titanium(IV) dichloride (L2TiCl2) have been studied. Outer sphere ion pairs [L2TiMe(S)]+[Me-MAO]- and [L2TiMe(S)]+[B(C6F5)4]- (S = solvent molecule), formed by activation of L2TiCl2 with MAO or with AlMe3/[CPh3]+[B(C6F5)4]-, and reactions of these ion pairs with ethene to afford chain-propagating species [L2TiP]+[Me-MAO]- and [L2TiP]+[B(C6F5)4]- (P = growing polymeryl chain) have been characterized by 1H, 13C, and 19F NMR spectroscopy

The silyl ethers 3-But-2-(OSiMe3)C6H3CH=NR (2a-e) have been prepared by deprotonation of the known iminophenols (1a-e) and treatment with SiClMe3 (a, R = C6H5; b, R = 2,6-Pri2C6H3; c, R = 2,4,6-Me3C6H2; d, R = 2-C6H5C6H4; e, R = C6F5). 2a-c react with TiCl4 in hydrocarbon solvents to give the binuclear complexes [Ti{3-But-2-(O)C6H3CH=N(R)}Cl(mu-Cl3)TiCl3] (3a-c). The pentafluorophenyl species 2e reacts with TiCl4 to give the known complex Ti{3-But-2-(O)C6H3CH=N(R)}2Cl2. The mononuclear five-coordinate complex, Ti{3-But-2-(O)C6H3CH=N(2,4,6-Me3C6H2)}Cl3 (4c), was isolated after repeated recrystallisation of 3c. Performing the dehalosilylation reaction in the presence of tetrahydrofuran yields the octahedral, mononuclear complexes Ti{3-But-2-(O)C6H3CH=N(R)}Cl3(THF) (5a-e). The reaction with ZrCl4(THF)2 proceeds similarly to give complexes Zr{3-But-2-(O)C6H3CH=N(R)}Cl3(THF) (6b-e). The crystal structures of 3b, 4c, 5a, 5c, 5e, 6b, 6d, 6e and the salicylaldehyde titanium complex Ti{3-But-2-(O)C6H3CH=O}Cl3(THF) (7) have been determined. Activation of complexes 5a-e and 6b-e with MAO in an ethene saturated toluene solution gives polyethylene with at best high activity depending on the imine substituent.

Reaction between 3-But-2-(OSiMe3)C6H3CH=N(2,6-R2C6H3) (where R = H (1a) or Pri (1b)) and TiCl4(THF)2 affords the octahedral complexes Ti{3-But-2-(O)C6H3CH=N(2,6-R2C6H3)}Cl3(THF) while in the absence of THF 1b reacts with TiCl4 to give the binuclear complex [Ti{3-But-2-(O)C6H3CH=N(2,6-Pri2C6H3)}Cl(µ–Cl)3TiCl3]; the complexes give good productivities for ethene polymerisation when activated with MAO