Gallium complexes based on aminobisphenol ligands

A series of aminobisphenol ligands containing different substituents both on the aromatic moieties and at the central nitrogen atom were synthesized by the Mannich reaction. The reaction of dilithium derivatives of these ligands with gallium trichloride affords the corresponding ONO-type gallium monochloride complexes. The replacement of the chlorine atom by a tert-butoxide moiety allows the preparation of reactive complexes, which efficiently initiate the ε-caprolactone polymerization. The activity of the synthesized complexes as polymerization initiators was studied. The structures of three aminobisphenols and three gallium complexes were determined by X-ray diffraction.