New Rare-earth Metal Alkvl Complexes Supported By Functionalized Indolyl Ligand In η~2：η~1-μ-η~1Bonding Mode: Synthesis, Haracterization And: Catalytic Activity For Isoprene Polymerization

Reactions of3-(CyN=CH)C8H5NH(1) with1equiv ofRE(CH2SiMe3)3(thf)2(RE=Y, Er, Yb) in toluene for4h, after evaporationof toluene and recrystallization from hexane, produced the dinuclearrare-earth alkyl complexes {[η1:η2-μ-η1-3-[CyNCHCH2Si(CH3)3]C8H5N]-Y[CH2Si(CH3)3](thf)}2in56%yield for RE=Y(2), in53%yield for RE=Er(3), in69%yield for RE=Yb(4) respectively. However, when thesolids were recrystallized from a mixed solvent of hexane and THF,another type of binuclear rare-earth alkyl complexes μ-{[η1:η1-3-[CyNCH-CH2Si(CH3)3]C8H5N]RE[CH2Si(CH3)3](thf)2}2were isolated in73%yield for RE=Y(5), in65%yield for RE=Er(6), in62%yield for RE=Yb(7). All the complexes were characterized by X-ray single crystaldiffraction.In the presence of organoaluminium and one equivalent of[Ph3C][B(C6F5)4], the complexes show better activity and regioselectivity(1,4-up to99%) for the isoprene polymerization depending on thesolvents.