Chelated anionic aluminum

Two equivalents of the bidentate ligands, 2,4-(R)₂-6-(CH₂NHR’)PhOH where R’ = alkyl and R = H (L₁) and ^tBu(L²) are combined with LiAlH₄ to form unique chelated aluminates of the form [(L¹)₂Al]Li(THG)₂ (R’ = ⁱPr (1), ⁱBu (2), ^tBu (3), Dipp (4) (Dipp = 2,6-(ⁱPr)₂Ph)) and [(L²)₂A1]Li(THF)₂ (R’ = ⁱPr (5), ⁱBu (6), ^tBu (7)). Compound 7 undergoes a salt elimination when combined with Me₂A1C1 to form the bimetallic derivative, (L²)₂A1 (A1Me₂) (R’ = ^tBu (8)). By comparison a related reaction with [ArO₄Al][Li(thf)₄] (Ar = 2,4-(^tBu)₂Ph (9)) leads to elimination of one of the aryloxide groups and the consequent formation of neutral species. All of the compounds were characterized by Mp, analyses, ¹H NMR, IR and, in the case of 4 and 7-9, by X-ray crystallography.