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

Abstract

The reaction of Ln(CH 2SiMe 3) 3(thf) 2 with 1 equiv. of the amine ligand 2,6- i Pr 2C 6H 3NH(SiMe 3) gave the corresponding amido-ligated rare earth metal bis(alkyl) complexes [2,6- i Pr 2C 6H 3N(SiMe 3)]Ln(CH 2SiMe 3) 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(μ-CH 2SiMe 2NC 6H 3 i Pr 2-2,6) 3(thf) 3 ( 5) through intramolecular C–H activation of a methyl group of Me 3Si on the amido ligand by Gd–CH 2SiMe 3 and the subsequent ligand redistribution. Complexes 1– 5 were structurally characterized by X-ray analyses. On treatment with 1 equiv of [Ph 3C][B(C 6F 5) 4] in toluene at room temperature, complexes 1– 4 showed high activity for the living polymerization of isoprene. The 1/[Ph 3C][B(C 6F 5) 4] system showed high activity also for the polymerization of 1-hexene and styrene.