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.

New ether-functionalized carboranyl-indenyl hybrid ligands were prepared. They can prevent lanthanocene chlorides from ligand redistribution reactions and offer samarium(Ⅱ) complexes unusual reactivities. Treatment of Me2SiCl(C9H6CH2CH2OMe) with 1 equiv of Li2C2B10H10 in toluene/Et2O afforded the monolithium salt [Me2Si(C9H5CH2CH2OMe)-(C2B10H11)]Li(OEt2) (2). Interaction of 2 with 1 equiv of n-BuLi in Et2O produced the dilithium salt [Me2Si(C9H5CH2CH2OMe)(C2B10H10)]Li2(OEt2)2 (3). Reaction of 3 with 1 equiv of LnCl3 at room temperature gave the complex salts of general formula [{[è5:ó-Me2Si(C9H5CH2CH2-OMe)(C2B10H10)]Ln(THF)(μ-Cl)3Ln[η5:η1:η-e2Si(C9H5CH2CH2OMe)(C2B10H10)]}2{Li(THF)}]-[Li(THF)4] (Ln) Y (4), Yb (5)). Upon heating, 5 was converted into [η5:η1:η-Me2Si(C9H5-CH2CH2OMe)(C2B10H10)]Yb(THF)(μ-Cl)2Yb[η5:η1:η-Me2Si(C9H5CH2CH2OMe)(C2B10H10)] (6) by eliminating LiCl. Treatment of 4 or 5 with 2 equiv of group 1 metal amides gave organorare-earth amide complexes [è5:è1:ó-Me2Si(C9H5CH2CH2OMe)(C2B10H10)]Y(NHC6H3-2,5-tBu2)-(μ-Cl)Li(THF)3 (8) or [η5:η1:η-Me2Si(C9H5CH2CH2OMe)(C2B10H10)]Yb(NHC6H3-2,6-iPr2)(í-Cl)Li(THF)3 (9). An equimolar reaction of SmI2 with 3 in THF generated, after addition of LiCl, [{[è5:η-Me2Si(C9H5CH2CH2OMe)(C2B10H10)]2Sm}{Li(THF)}]n (10) and [{η5:η1:η6-Me2-Si(C9H5CH2CH2OMe)(C2B10H10)Sm}2(í-Cl)][Li(THF)4] (11). In sharp contrast, a less reactive YbI2 reacted with 3 in THF, producing only salt metathesis product [η5:η1:η-Me2Si(C9H5-CH2CH2OMe)(C2B10H10)]Yb(DME)(THF) (12). 12 reacted with 1 equiv of 3 to give the ionic complex {[(μ-η5:η2):η1:η-Me2Si(C9H5CH2CH2OMe)(C2B10H10)]2Yb}{Li(THF)2}2 (13). All complexes were characterized by various spectroscopic techniques and elemental analyses. The structures of 5, 6, and 8-13 were further confirmed by single-crystal X-ray analyses.

Reaction of Me2Si(Me2NCH2CH2C9H6)Cl with 1 equiv of t-BuNHLi yielded Me2Si(Me2-NCH2CH2C9H6)(t-BuNH) (1). Treatment of Me2NCH2CH2C9H7 with 1 equiv of n-BuLi, followed by reaction with an excess of Me3SiCl, produced Me2NCH2CH2C9H6SiMe3 (2) in 9% yield. Interaction of YbCl3 with 3 equiv of (Me3Si)2NLi in THF, after workup, produced the tetracoordinate ytterbium(Ⅲ) amide [(Me3Si)2N]3YbⅢ　(μ-Cl)Li(THF)3 (3) in 85% yield. Treatment of 3 with 2 equiv of 1 gave the ytterbium(Ⅱ) complex [è5:è1-Me2Si(Me2NCH2-CH2C9H5)(t-BuNH)]2YbⅡ (4) in 58% yield via a reductive reaction. To get some insight into the reaction, several reactions were initiated to study the effects of the t-BuNH group, silyl group, and N,N-dimethylaminoethyl group of the indene compounds, effects of coordinate ClLi(THF)3 in 3, and temperature effect on the reductive reaction. Treatment of 3 with-equiv of 2 afforded (η5:η1-Me2NCH2CH2C9H5SiMe3)2YbII (5) in 52% yield. Interaction of 3 with 2 equiv of Me2NCH2CH2C9H7 produced a ytterbium(Ⅱ) complex (η5:η1-Me2NCH2-CH2C9H6)2YbⅡ (6) in 63% yield. Treatment of the ytterbium(Ⅲ) complex [(Me3Si)2N]3YbIII with 2 equiv of Me2NCH2CH2C9H7 also afforded the ytterbium(Ⅱ) complex (η5:η1-Me2NCH2-CH2C9H6)2YbII (6) in 62% yield, which provides an alternate method for the preparation of 6. Treatment of 3 with 2 equiv of indene(C9H8) produced the ytterbium(Ⅲ) complex (η5-C9H7)2YbIIIN(SiMe3)2 (7). Treatment of 3 with 1 equiv of 1,2-bis(indenyl)ethane also produced the ytterbium(Ⅲ) complex meso-[ethylenebis(è5-indenyl)ytterbiumⅢ bis(trimethylsily)amide ((EBI)YbIIIN(SiMe3)2) (8). All the compounds were fully characterized by spectroscopic methods and elemental analyses. Complexes 3, 4, 5, 6, and 8 were additionally characterized by a single-crystal X-ray diffraction study. The formation pathway for the ytterbium(Ⅱ) complexes is proposed. The study showed that ytterbuim(Ⅱ) complexes 4, 5, and 6 can function as single-component MMA polymerization catalysts with good activity.

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.

The interaction of methoxyethyl functionalized indene compounds (C9H6-1-R-3-CH2CH2OMe, R=t-BuNHSiMe(1), Me3Si (2), H (3)) with [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln=Yb (4), Eu (5)) produced a series of new ytterbium (Ⅱ) and europium (Ⅱ) complexes via tandem silylamine elimination/homolysis of the Ln-N (Ln=Yb, Eu) bond.Treatment of the lanthanide (Ⅱ) amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln=Yb (4), Eu (5) with 2 equiv. of 1, 2and 3, respectively, produced, after workup, the ytterbium (Ⅱ) complexes [η5:η1-Me2Si(MeOCH2CH2C9H5)(NHBu-t)]2-YbII (6), (η5:η1-MeOCH2CH2C9H5SiMe3)2YbII (7), (η5:η1-MeOCH2CH2C9H6)2YbII (8) and the correspondingeuropium (Ⅱ) complexes [η5:η1-Me2Si(MeOCH2CH2C9H5)(NHBu-t)]2EuII (9), (η5:η1-MeOCH2CH2C9H5SiMe3)2EuII (10) and (η5:η1-MeOCH2CH2C9H6)2EuII (11) in moderate to good yield. In contrast, interaction of the corresponding indene compounds 1, 2 or 3 with the lanthanide amides [(Me3Si)2N]3Ln (Ln = Yb, Eu) was not observed, while addition of 0.5 equiv. of anhydrous LiCl to the corresponding reaction mixture produced, after workup, the corresponding ytterbium (Ⅱ) or europium (Ⅱ) complexes. All the new compounds were fully characterized by spectroscopic and elemental analyses. The structures of complexes 7, 9 and 10 were determined by single-crystal X-ray analyses. The catalytic activity of all the ytterbium (Ⅱ) and europium (Ⅱ) complexes on MMA polymerization was examined. It was found that all the ytterbium (Ⅱ) and europium (Ⅱ) complexes can function as single-component MMA polymerization catalysts. The temperature, solvent and ligand effects on the catalytic activity were studied.