Incorporating trimethylaluminium into the structures of alkali metal (Li, Na, K, Cs) dihydropyridines

AbstractCo‐complexation of equimolar amounts of 1‐alkali‐metal‐2‐tertbutyldihydropyridines with AlMe3 in the presence of a polydentate N‐donor ligand has delivered four crystallographically verified alkali‐metal aluminates [donor⋅AM(μ‐tBuDHP)AlMe3]n (1, AM=Li, donor=TMEDA, n=1; 2, AM=Na, donor=PMDETA, n=1; 3, AM=K, donor=PMDETA, n=2; 4, AM=Cs, donor=PMDETA, n=∞; TMEDA=N,N,N′,N′‐tetramethylethylenediamine; PMDETA=N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine). While the monomeric complexes (1, 2) and the polymeric complex (4) are thermally stable, the dimeric complex (3) undergoes a disproportionation process yielding the known ion‐separated homoanionic complex [K ⋅ (PMDETA)2]+ [AlMe4]− (3 a). Utilizing TMEDA as the N‐donor resulted in the same disproportionation, but gave rise to two distinct solid‐state aggregated forms of aluminate [K ⋅ (TMEDA)2]+ [AlMe4]−, namely monomeric (3 b) and polymeric (3 b′) polymorphs, in which the anionic moiety acts as a bidentate chelator or monodentate bridge respectively to the potassium cationic moieties.