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Sidearm Effects. Synthesis, Structural Characterization, and Reactivity of Lanthanides Incorporating a Linked Carboranyl-Indenyl Ligand with a Tethered Amine Group

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posted on 02.08.2004, 00:00 by Shaowu Wang, Hung-Wing Li, Zuowei Xie
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(μ-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:σ-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)]Yb(NHC6H3-2,6-Pri2) (9) or [η5:η1:σ-Me2Si(C9H5CH2CH2NMe2)(C2B10H10)]Sm(μ-NHC6H3-2,6-Pri2)(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(C9H5CH2CH2NMe2)(C2B10H10)]2Yb}{Li(THF)2}2 (12). All complexes were characterized by spectroscopic techniques and elemental analyses. Their structures were all further confirmed by single-crystal X-ray analyses.