Synthesis of rare earth metal complexes incorporating amido and enolate mixed ligands: Characterization and reactivity

The reactions of 2,6-(R)2C6H3NHSiMe3 (R = iPr or Et) with excess nBuLi in THF or n-hexane, followed by treatment with LnCl3, produced different kinds of rare earth metal complexes. Complexes incorporating amido and enolate mixed ligands having the general formula (CH2CHO)Ln[2,6-(iPr)2C6H3NSiMe3]2(μ-Cl)Li(THF)3 (Ln = Y(1), Yb(2)) were prepared by the reaction of N-trimethylsilyl-2,6-diisopropylaniline 2,6-(iPr)2C6H3NHSiMe3 with excess nBuLi in THF, followed by treatment with LnCl3. Complexes with the formula [2,6-(Et)2C6H3NSiMe3]2Y(THF)(μ-Cl)2Li(THF)2 (3) and {[2,6-(Et)2C6H3NSiMe3]3YCl}[Li(THF)4] (4) were isolated when 2,6-(Et)2C6H3NHSiMe3 was treated with nBuLi in n-hexane, followed by treatment with 1/2 or 1/3 equiv. of YCl3 in THF, respectively. All the structures of the complexes were determined by single-crystal X-ray analyses. Investigation on the reactivity of complexes 1 and 2 towards aromatic aldehydes indicated that the amido ligand of complexes 1 and 2 could selectively react with aromatic aldehydes to afford the disproportionation products of amides and alcohols. The reaction of the lithium amide {[2,6-(iPr)2C6H3](Me3Si)N}Li with aromatic aldehydes in the presence of a catalytic amount of YCl3 was also studied.

Graphical abstractThe reaction of 2,6-(iPr)2C6H3NHSiMe3 with excess nBuLi in THF, followed by treatment with LnCl3, produced rare earth metal complexes incorporating amido and enolate mixed ligands.Figure optionsDownload full-size imageDownload as PowerPoint slide