Novel hexanuclear and octanuclear zinc alkyl cages derived from a bis-oxamidate ligand

1 and 2 were prepared by coordination self-assembly from reacting N,N′-bis(3,5-di-tert-buthyl-2-phenol)oxamide (L-H4) with ZnEt2 in toluene and THF, respectively. The molecular X-ray structures show 1 as an octanuclear Zn8 cage and 2 as a hexanuclear Zn6 cage. The nuclearity of these cages is driven by the solvent, in fact 1 gives 2 upon addition of THF. Good polymer conversions for the ROP of rac-lactide were achieved by using 1 and 2 with alcohols as co-catalysts.