Homolysis Of The Ln-N Bond. Synthesis, Structure And Catalytic Behavior Of Organolanthanide Complexes With 2-Picolyl Functionalized Indenyl Ligands And Dimethylsilylene-Bridged Indenyl Ligands

All experiments were carried out under the dry and oxygen-free argon atmosphere by using standard Schlenk techniques. Reaction of 2-(C1CH2)C5H4N·HCl with 2 equiv of C9H7Li in THF at 0℃ yielded 3-(2-C5H4NCH2)C9H7(1) in 73% yield, 1 reacted with 1 equiv of n-BuLi in THF at 0℃ yielded 3-(2-C5H4NCH2)C9H6Li, interaction of 3-(2- C5H4NCH2)C9H6Li with excess Me3SiCl yielded 1-SiMe3-3-(2-C5H4N CH2)C9H6(2) in 85% yield. Reaction of (CH3)2SiCl2 with 2 equiv of C9H7Li in Et2O at 0℃ yielded(CH3)2Si(C9H7)2 (3) in 64% yield.Interaction between [(Me3Si)2N]3YbⅢ(μ-Cl)Li(THF)3 and 2 equiv of 1 in refluxed toluene for 24 hours,after recrystallization from toluene, gave an ytterbium(II) complex [η5:η1-3-(2-C5H4NCH2)C9H6]2YbⅡ(4) in 67% yield. Treatment of [(Me3Si)2N]3EuⅢ(μ-Cl)Li(THF)3 with 2 equiv of 1 in hot toluene at 50℃,after recrystallization from toluene,gave a europium(II) complex [η5:η1-3-(2-C5H4NCH2)C9H6]2EuⅡ(5) in 74% yield. Interaction of [(Me3Si)2N]3YbⅢ(μ-Cl)Li(THF)3 with 2 equiv of 2 in refluxed toluene for 24 hours,after recrystallization from toluene,gave an ytterbium(II) complex [η5:η1-1-SiMe3-3-(2-C5H4NCH2)C9H5]2YbⅡ·1/2LiCl(6) in 59% yield. Treatment of [(Me3Si)2N]3EuⅢ(μ-Cl)Li (THF)3 with 2 equiv of 2 in hot toluene at 50℃,after recrystallization from toluene,gave a europium (II) complex [η5:η1-1-SiMe3-3- (2-C5H4NCH2)C9H5]2EuⅡ(7) in 61% yield. Interaction of 3 with 1 equiv of [(Me3Si)2N]3YbⅢ(μ-Cl)Li(THF)3 by addition of a drop of THF in refluxed toluene for 24 hours, after recrystallization from toluene, gave an ytterbium(Ⅲ) complex [η5:η5-(CH3)2Si(C9H6)2YbⅢ]2(μ-Cl)[(μ-O)Li(THF)2](8) in 56% yield. Interaction between 3 and 1 equiv of [(Me3Si)2N]3YbⅢ(μ-Cl)Li(THF)3 by addition of a drop of TMEDA in refluxed toluene for 24 hours, after recrystallization from toluene, gave an ytterbium(Ⅱ) complex [η5:η5-(CH3)2Si(C9H6)2] YbII(TMEDA)(9) in 68% yield. All the complexes were fully characterized by elemental and spectroscopic analyses. The structure of complexes 4, 6, 8 was determined by X-ray diffraction.On the basis of the above experimental results, these experiments further certify that the internal donor ligands coordination promoted homolytic reaction of the Ln-N bond can be extended to external donor ligands promoted homolytic reaction of the Ln-N bond . The oxygen atom abstraction is observed when the external donor ligand is THF. This work provides a new methodology to prepare organolanthanide (Ⅱ) complexes.The activities of all complexes as single-component catalysts in catalyzing MMA andε-CL polymerization were examined. It was found that the complex 8 showed high catalytic activity on MMA polymerization in solvents toluene and DME. The complex 5 showed catalytic activity on MMA polymerization in solvents toluene and DME, and catalytic activity on ε-CL polymerization in solvent toluene. Other complexes cannot show catalytic activity on MMA andε-CL polymerization.