Rare earth metal bis(alkyl) complexes bearing a monodentate arylamido ancillary ligand: Synthesis, structure, and Olefin polymerization catalysis

The reaction of Ln(CH2SiMe3)(3)(thf)(2) with 1 equiv. of the amine ligand 2,62Pr(2)C(6)H(3)NH(SiMe3) gave the corresponding amido-ligated rare earth metal bis(alkyl) complexes [2,6-Pr2C6H3N(SiMe3)]Ln(CH2SiMe3)(2)(thf) (Ln = Sc (1), Y (2), Ho (3), Lu (4)), which represent rare examples of bis(alkyl) rare earth metal complexes bearing a monodentate anionic ancillary ligand. In the case of Gd, a similar reaction gave the bimetallic complex Gd-2(mu-CH2SiMe2NC6H3'Pr-2-2,6)(3)(thf)(3) (5) through intrarnolecular C-H activation of a methyl group of Me3Si on the amido ligand by Gd-CH2SiMe3 and the subsequent ligand redistribution. Complexes 1 5 were structurally characterized by X-ray analyses. On treatment with I equiv of [Ph3C][B(C6F5)(4)] in toluene at room temperature, complexes 1-4 showed high activity for the living polymerization of isoprene. The 1/[Ph3C][B(C6F5)(4)] system showed high activity also for the polymerization of 1-hexene and styrene. (c) 2006 Elsevier B.V. All rights reserved.