A series of monometallic and bimetallic Al(III) complexes with substituted naphthyl based Schiff base ligands have been prepared and characterised. When 1-aminonaphthalene based ligands were reacted with AlMe3 monometallic complexes were isolated, however, with 1,5 and 1,8- diaminonaphthalene based ligands bimetallic complexes were formed. In all cases 4-coordinate tetrahedral Al(III) centres were observed in the solid state and in solution. There was little difference in rate of polymerisation of rac-lactide between the monometallic and bimetallic complexes based on 1,5-diaminonaphthalene. However, for the 1,8-diaminonaphthalene the complex was an order of magnitude faster than the monometallic and the analogous 1,5-system. Moreover, this complex was active at room temperature, which is rare for aluminium initiators, and PLA with a high degree (Pm = 0.82) of isotacticity was observed.
Kirk, S. M., Quilter, H. C., Buchard, A., Thomas, L. H., Kociok-Kohn, G., & Jones, M. D. (2016). Monomeric and dimeric Al(III) complexes for the production of polylactide. Dalton Transactions , 45(35), 13846-13852. https://doi.org/10.1039/C6DT02861F