Bimetallic aluminum and gallium chelates with N₂O₂ ligands

A wide range of bimetallic aluminum molecules are formed in combinations between Salen Schiff base ligands and either AlR₃ or AlR₂Cl. They are of the general formulas L(AlR₂)₂ and L(AlRCl)₂ with R = alkyl and L = Salen(^tBu) ligand with relatively unusual `backbone' connections between the nitrogen atoms, 1,2-cyclohexylene (Salcen(<sup>t</sup>Bu)), 1,4-butylene (Salben(<sup>t</sup>Bu)), 1,5-pentylene (Salpten(<sup>t</sup>Bu)), 1,6-hexylene (Salhen(<sup>t</sup>Bu)), and 1,4-phenylene (1,4-Salophen(<sup>t</sup>Bu)). Additionally, previously unknown ligands were employed with the `backbones' 1,4-bis(p-aminobenzyl)benzene (Salmaben(^tBu)), 1-(m-aminobenzoyl)-4-(m-aminobenzyl)benzene (Salmabmaben(^tBu)), and 4,4′-bis(m-aminobenzoyl)diphenylmethane (Salmadmen(^tBu)). The ligands for these compounds were designed to feature two group 13 sites at long and varying distances from one another. The compounds were characterized by mp analyses, IR, and ¹H NMR, and X-ray structures were determined for the examples R,R′-Salcen(^tBu){AlMe₂}₂ (1), Salben(^tBu){AlMe₂}₂ (2), 1,4-Salophen(^tBu){GaEt₂}₂ (7), R,R′-Salcen(^tBu){AlMeCl}₂ (11), Salben(^tBu){AlMeCl}₂ (13), and Salhen(^tBu){AlMeCl}₂ (14).