Organoaluminum-Assisted Formation of Rare-Earth Metal Imide Complexes

The μ2-imide complexes [Ln(AlMe4)(μ2-Nmes*)] x (mes* = C6H2 tBu3-2,4,6) (Ln = Y, La, Nd, Lu) are synthesized from homoleptic heterobimetallic complexes Ln(AlMe4)3 utilizing two distinct protocols: reaction with 2,4,6-tri-tert-butylaniline in hexane via methane elimination or with potassium (2,4,6-tri-tert-butylphenyl)amide in toluene according to a salt metathesis–protonolysis tandem reaction. Complexes [Ln(AlMe4)(μ2-Nmes*)]2 (Ln = Y, Nd, Lu) revealed isomorphous solid-state structures, featuring an asymmetrically bridged Ln2N2 core with very short Ln–N distances (2.071(1)–2.155(3) Å). In the solid-state structure of the lanthanum derivative similar dimeric subunits assemble as La4Al4 oligomers through μ2-η1:η2-bridging tetramethylaluminato moieties. [La(AlMe4)(μ2-Nmes*)]4 displays La---arene interactions (2.702(6) Å) that are considerably shorter than the La(μ-CH3)aluminato bond lengths.