Synthesis, structure, and catalytic activity of dinuclear aluminium bis(amidinate) and bis(guanidinate) complexes

Abstract

Eight dinuclear methyl aluminium(III) bis(amidinate) and bis(guanidinate) complexes have been synthesized in good to very good yields and were fully characterized by means of ¹H, ¹³C, and IR spectroscopy as well as elemental analysis. Five of them were successfully converted to the respective dinuclear aluminium iodide complexes and a dinuclear aluminium chloride bis(amidinate) complex was directly accessed by deprotonation of the ligand using ethyl aluminium dichloride. The molecular solid-state structures of eleven complexes were obtained from X-ray diffraction analysis. Furthermore, the catalytic activity of the dinuclear methyl aluminium complexes 3 and 4 has been probed in the ring-opening polymerization of ε-caprolactone and L-lactide and the results highlight the impact of the metal–metal separation and the ligands’ backbone on activity and selectivity.