Synthesis and characterization of titanium ketimide complexes Ti(N [dbnd]C tBu 2) nCl 4− n ( n = 1, 2): Ethylene polymerization studies

Abstract

Compounds [Ti(N C t Bu 2)Cl 3] 2, 1, [Ti(N C t Bu 2) 2Cl 2] 2, 2, [Ti(N C t Bu 2)(CH 2Ph) 3], 3, [Ti(N C t Bu 2) 2(CH 2Ph) 2], 4, [Ti(N C t Bu 2)(CH 2Ph) 2(μ-CH 2PhB(C 6F 5) 3], 5 and [Ti(N C t Bu 2) 2(CH 2Ph) (μ-CH 2PhB(C 6F 5) 3], 6, are described. 1 was obtained from the reaction of TiCl 4 and Me 3SiN C t Bu 2 and used as starting material for the preparation of 2 and 3. Complex 4 was obtained by reaction of 2 with PhCH 2MgCl. Complexes 5 and 6 were prepared by addition of B(C 6F 5) 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.