Group 13 Cation Formation with a Potentially Tridentate Ligand

Abstract

A potentially tridentate ligand, Phensal(tBu)H 3, was prepared by the condensation of 1 equiv of phenylenediamine with 3,5-di- tert -butylsalicylaldehyde. When 1 equiv of this new ligand is added to AlMe 3, [[Phensal(tBu)HAlMe]] 2 ( 1 ) results. In contrast, this reaction with GaMe 3 produces [Phensal(tBu)H 2 ]GaMe 2 ( 2 ). When 1 or 2 equiv of Phensal(tBu)H 3 is combined with Et 2 AlCl, the complex [Phensal(tBu)] 2 AlCl ( 3 ) forms. However the same reaction with Me 2 GaCl leads to [Phensal(tBu)H 2 ]Ga(Me)Cl ( 4 ). A cationic complex, {[Phensal(tBu)] 2 Al} + Cl - ( 5 ), is formed when 3 is dissolved in MeOH. The MeOH apparently mediates the formation of the cation but does not coordinate the cationic metal. When the solvent is removed, 5 reverts back to neutral 3 . When 3 is combined with GaCl 3 in toluene, another cationic complex, {[Phensal(tBu)H 2 ] 2 Al} + GaCl 4 - ( 6 ), is formed. In a similar manner, {[Phensal(tBu)H 2 ] 2 Al} + Me 2 AlCl 2 - ( 7 ) is formed by adding Me 2 AlCl to 3 . The compounds were characterized by mp, elemental analyses, IR, 1 H and 27 Al NMR, and in the case of 2, 5, and 6 single-crystal X-ray analysis.