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

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.