Synthesis, Characterization And Catalytic Activity Of Divalent Lanthanide Complexes With (2-Methoxy-Phenyl) Isopropyl Functionalized Indenyl Ligands

All experiments were carried out under a dry and oxygen-free argon atmosphere by using standard Schlenk techniques. Reaction of 6, 6-dime thylbenzofulvene [C₉H₆-1-C(CH₃)₂] with 1 equiv of o-CH₃O-C₆H₄Li in Et₂O yielded 3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₇ (1) in 79% yield, 1 reacted with 1 equiv of n-BuLi yielded in THF at 0oC yielded 3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆Li. Interaction of 3-[o-CH₃O-C₆H₄-C (CH-3)₂]C₉H₆Li with excess Me3SiCl, after recrystallization from hexane, yielded 1-Me₃Si-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₇ (2) in 89% yield. Interaction of 1 with 1 equiv of n-BuLi by addition of a drop of DME in Et₂O yielded 3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆Li(DME) (3) in 89% yield. All the compounds were fully characterized by spectroscopic methods and elemental analyses. Complex (3) was additionally characterized by a single-crystal X-ray diffraction study. Treatment of [(Me₃Si)₂N]₃Yb^Ш(μ-Cl)Li(THF)₃ with 2 equiv of 1 or 2 respectively in reflux toluene gave the corresponding ytterbium(П) complexes {η⁵:η¹-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆}₂Yb^П(4) in 84% yield, {η⁵:η¹-1-Me₃Si-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆}₂YbП(5) in 62% yield. Treatment of [(Me₃Si)₂N]₃Eu^Ш(μ-Cl)Li(THF)₃ and 2 equiv of 1 or 2 respectively in toluene at 60°C gave the corresponding europium(П) complexes {η⁵:η¹-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H-6}₂Eu^П(6) in 81% yield, {η⁵:η¹-1-Me₃Si-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆}₂Eu^П(7) in 60% yield. Treatment of [(Me3_Si)₂ N]₃Sm^Ш(μ-Cl)Li(THF)₃ and 2 equiv of 1 or 2 respectively in reflux toluene gave the corresponding samarium(П) complexes {η⁵:η¹-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆}₂SmП(8) in 72% yield, {η⁵:η¹-1-Me₃Si-3-[o-CH₃O-C₆H₄-C(CH₃)₂]C₉H₆}₂SmП(9) in 83% yield. These results further certify the oxygenatom coordination promoted homolytic cleavage of the Ln-N(Ln = Yb,Eu,Sm) bond. This work further extends the new methodology to prepare organolanthanide(П) complexes. At the same time, We have studied the catalytic activity of the above organolanthanide(П) complexes, the complexes [η⁵:η¹-(Me₂NCH₂CH₂ C₉H₅SiMe₃)]₂Eu^П(10) and [η⁵:η¹-Me₂Si(Me₂NCH₂CH₂C₉H₅)(t-BuN H)]₂Yb^П(11) as polymerization catalysts for Methyl methacrylate,ε-caprolactone. Studies showed that ligands, lanthanide cations, the solvents,temperatures, the mole ratio of catalyst and monomer,the volume ratio of monomer and solvent have influences on activities of catalysts,stereoregularity and the molecular weight distribution of polymer.