Compounds [Ti(N =(CBu2)-Bu-t)Cl-3](2), 1, [Ti(N =(CBu2)-Bu-t)(2)Cl-2](2), 2, [Ti(N =(CBu2)-Bu-t)(CH2Ph)(3)], 3, [Ti(N =(CBu2)-Bu-t)(2)(CH2Ph)(2)], 4, [Ti(N =(CBu2)-Bu-t)(CH2Ph)(2)(mu-CH2PhB(C6F5)(3)], 5 and [Ti(N =(CBu2)-Bu-t)(2)(CH2Ph) (mu-CH2PhB(C6F5)(3)], 6, are described. 1 was obtained from the reaction of TiCl4 and Me3SiN =(CBu2)-Bu-t and used as starting material for the preparation of 2 and 3. Complex 4 was obtained by reaction of 2 with PhCH2MgCl. Complexes 5 and 6 were prepared by addition of B(C6F5)(3) to 3 and 4, respectively. The NMR spectra of 5 and 6 reveal that these complexes exist in solution as zwitterions with one benzyl ligand bridging the titanium and boron centres. Complexes 1 and 2 are ethylene polymerization catalysts when activated with MAO, displaying activities of 217.1 and 794.6 kg/(mol(Ti[E]) h), respectively. (C) 2007 Elsevier B.V. All rights reserved.