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 NMe 2 to the central metal ion, leading to the isolation of kinetic products and monomeric neutral species. Treatment of Me 2 SiCl(C 9 H 6 CH 2 CH 2 NMe 2 ) with 1 equiv of Li 2 C 2 B 10 H 10 afforded the monolithium salt [Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 11 )]Li(OEt 2 ) ( 2 ). Interaction of 2 with 1 equiv of n -BuLi produced the dilithium salt [Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )]Li 2 (OEt 2 ) 2 ( 3 ). Treatment of 3 with 1 equiv of YbCl 3 gave [{ η 5: η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )}YbCl 2 ][Li(THF) 4 ] ( 4 ). Upon heating, 4 was converted to [{ η 5: η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )}Yb( μ -Cl) 1.5 ] 2 [Li(THF) 4 ] ( 6 ) and finally to [{ η 5: η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )}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 [ η 5: η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )]Yb(NHC 6 H 3 -2,6-Pr i 2 ) ( 9 ) or [ η 5: η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )]Sm( μ -NHC 6 H 3 -2,6-Pr i 2 )( μ -Cl)Li(THF) ( 8 ). An equimolar reaction of SmI 2 with 3 generated, after addition of LiCl, [{ η 5: η 1: η 6 -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )Sm} 2 ( μ -Cl)][Li(THF) 4 ] ( 10 ). In sharp contrast, a less reactive YbI 2 reacted with 3 in THF, producing only the salt metathesis product [ η 5: η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )]Yb(DME) ( 11 ). 11 reacted with 1 equiv of 3 to give the ionic complex {[( μ - η 5: η 2 ): η 1: σ -Me 2 Si(C 9 H 5 CH 2 CH 2 NMe 2 )(C 2 B 10 H 10 )] 2 Yb}{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.