Rare-Earth Metal Bis(dimethylsilyl)amide Complexes Supported by Cyclooctatetraenyl Ligands

摘要

Monomeric cycloocta tetra enyl rare-earth metal complexes (COT)LnI(thf)(3) were examined by X-ray structure analysis for Ln = La and Sm being isostructural to the Nd and Cc congeners. Reaction of the lanthanum derivative with excess AlMe3 led to partial thf displacement and dimerization to [(COT)La(mu-I)(thf)(2)](2). I-/[N(SiHMe2)(2)](-) salt metathetic ligand exchange involving (COT)LnI(thf)(3) (Ln = La, Nd, Sm) and Li[N(SiHMe2)(2)] did not give putative {(COT)Ln[N(SiHMe2)(2)](-) (thf)(x)}. Instead, depending on the metal size, the mixed iodide/amide ate complexes (COT)Ln(mu-I)(2){mu-N(SiHMe2)(2)}Ln-(COT)][Li(thf)(4)] (Ln = Nd, Sm) and (COT)La(mu-I)[mu-N(SiHMe2)(2)](2)La[mu-(eta(2):eta(8)-COT)]Li(thf)(3) were obtained and identified by X-ray structure analyses. In thf solvent, these heteroleptic complexes undergo ligand redistribution to (COT)Ln[mu-(eta(2):eta(8)-COT)]Li(thf)(3), whose solid-state structures were also analyzed by X-ray diffraction (Ln = Nd, Sm). Utilization of K[N(SiHMe2)(2)] afforded alkali-metal-free (COT)La[N(SiHMe2)(2)](thf)(2) in good yield, whose monomeric composition was determined by X-ray structure analysis. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)