Two new indene compounds, C9H7CH2SiMe2NC4H8 (1) and C9H6-1-Me-3-CH2SiMe2NC4H8 (2), were synthesized by the reaction of C9H6RLi (R) H, Me) with ClCH2SiMe2Cl, followed by treatment with lithium pyrrolidinide C4H8NLi. The interaction of [(Me3Si)2N]3Eu(μ-Cl)-Li(THF)3 with 2 equiv of 1 in refluxing toluene produced, after workup, a novel triple-decker sandwich tetranuclear europium(Ⅱ) compound, [{η:5η:5η1-(C9H5CH2SiMe2NC4H8)2}Eu2(μ-Cl)]2-[μ-η3:η5:η1:η3:η5:η1-(C9H5CH2SiMe2NC4H8)2]âC7H8â(C6H6)0.5 (3), with a coupled indenyl ligand through tandem silylamine elimination, reduction of Eu3+ to Eu2+, and the C-C coupling reactions. To probe the formation pathway of complex 3, the interaction of C9H6-1-Me-3-CH2SiMe2NC4H8 (3) with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 was studied. Treatment of [(Me3-Si)2N]3Eu(μ-Cl)Li(THF)3 with 2 equiv of 2 in refluxing toluene temperature or at 60℃ produced, after workup, a monomeric europium(Ⅱ) complex, (η5:η1-C9H5-1-Me-3-CH2SiMe2-NC4H8)2Eu (4), via tandem silylamine elimination/homolysis of the Eu-N bond reactions. The formation pathway for complex 3 was proposed. All the compounds were fully characterized by spectroscopic methods and elemental analyses, and the structures of complexes 3 and 4 were additionally determined by single-crystal X-ray diffraction analyses. It was found that complexes 3 and 4 can function as single-component MMA polymerization initiators, which represent the first examples of europium(Ⅱ) complexes as single-component MMA polymerization catalysts. The solvents and temperature effects' on the activities of the catalysts were also discussed.

A new amine-functionalized carboranyl-indenyl hybrid ligand shows unique properties in stabilizing various kinds of lanthanocene chloride complexes via increasing steric effects imposed by the coordination of NMe2 to the central metal ion, leading to the isolation of kinetic products and monomeric neutral species. Treatment of Me2SiCl(C9H6CH2CH2NMe2) with 1 equiv of Li2C2B10H10 afforded the monolithium salt [Me2Si(C9H5CH2CH2NMe2)-(C2B10H11)]Li(OEt2) (2). Interaction of 2 with 1 equiv of n-BuLi produced the dilithium salt [Me2Si(C9H5CH2CH2NMe2)(C2B10H10)]Li2(OEt2)2 (3). Treatment of 3 with 1 equiv of YbCl3 gave [{η5:η1:σ-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)}YbCl2][Li(THF)4] (4). Upon heating, 4 was converted to [{η5:η1:σ-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)}Yb(μ-Cl)1.5]2[Li(THF)4] (6) and finally to [{η5:η1:σ-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)}Yb(í-Cl)]2 (7) via the elimination of LiCl. Treatment of 6 or its Sm analogue 5 with 2 equiv of sodium amide gave [η5:η1:ó-Me2-Si(C9H5CH2CH2NMe2)(C2B10H10)]Yb(NHC6H3-2,6-Pri 2) (9) or [η5:η1:σ-Me2Si(C9H5CH2CH2-NMe2)(C2B10H10)]Sm(μ-NHC6H3-2,6-Pri 2)(μ-Cl)Li(THF) (8). An equimolar reaction of SmI2 with 3 generated, after addition of LiCl, [{η5:η1:η6-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)Sm}2-(μ-Cl)][Li(THF)4] (10). In sharp contrast, a less reactive YbI2 reacted with 3 in THF, producing only the salt metathesis product [η5:η1:σ-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)]Yb(DME) (11). 11 reacted with 1 equiv of 3 to give the ionic complex {[(μ-η5:η2):η1:σ-Me2Si(C9H5CH2CH2-NMe2)(C2B10H10)]2Yb}{Li(THF)2}2 (12). All complexes were characterized by spectroscopic techniques and elemental analyses. Their structures were all further confirmed by singlecrystal X-ray analyses.

We have synthesized a new series of ytterbium(Ⅱ) and europium(Ⅱ) complexes by tandem silylamine elimination/homolysis of Ln−N (Ln=Yb, Eu) bonds. The interaction of 2 equiv. of C9H7CH2CH2CH2NMe2 (1) with [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln=Yb, Eu) in toluene under reflux produced lanthanide(Ⅱ) complexes [(η5:η1-C9H6CH2CH2CH2NMe2)2-Ln] [Ln=Yb (2), Eu(3)] in 67 and 74% yields, respectively. Treatment of 2 equiv. of Me2Si(Me2NCH2CH2C9H6)(NHtBu) with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 in toluene at 80℃ afforded a europium(Ⅱ) complex [η5:η1-Me2Si(Me2NCH2-CH2C9H5)(NHtBu)]2Eu·(OC4H8)0.5 (4) in 46% yield. The interaction of 2 equiv. of Me2NCH2CH2C9H6SiMe3 with [(Me3-Si)2N]3Eu(μ-Cl)Li(THF)3 produced a europium(Ⅱ) compound [η5:η1-(Me2NCH2CH2C9H5SiMe3)]2Eu (5) in 49% yield. Treatment of 2 equiv. of Me2NCH2CH2C9H7 with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 in toluene gave a europium(Ⅱ) complex (η5:η1-Me2NCH2CH2C9H6)2Eu (6) in 57% yield. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of the complexes 4, 5, and 6 were determined by single-crystal X-ray analyses. The catalytic activities of organometallic complexes were examined; we found that all of the complexes can function as single-component MMA polymerization catalysts with good activity. We studied the effects of solvent and temperature on the catalytic activities and the stereochemistries of the polymers.

Summary: Treatment of Me2Si(C5H5)Cl with Li2C2B10H10 followed by hydrolysis gave the new versatile ligand Me2-Si(C5H5)(C2B10H11) in 79% isolated yield, which can be converted into the monoanion, dianion, and trianion, respectively. It makes possible the synthesis of a wide range of organometallic complexes.