Organoaluminum-Assisted Formation of Rare-Earth Metal Imide Complexes

The μ₂-imide complexes [Ln­(AlMe₄)­(μ₂-Nmes*)]_<i>x</i> (mes* = C₆H₂<i>t</i>Bu₃-2,4,6) (Ln = Y, La, Nd, Lu) are synthesized from homoleptic heterobimetallic complexes Ln­(AlMe₄)₃ utilizing two distinct protocols: reaction with 2,4,6-tri<i>-tert</i>-butylaniline in hexane via methane elimination or with potassium (2,4,6-tri-<i>tert</i>-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