Synthesis and characterization of hetero-bimetallic aryloxides and application in the polymerization of lactides

The reactions of 2,2′-ethylidene-bis(4,6-di-tert-butylphenol) (EDBPH2) with sodium/potassium and (nBu)2 Mg in tetrahydrofuran (THF), give [(EDBP)2 Mg][(Na)2(THF)5]·THF (1) and [(EDBP)2 Mg][(K)2(THF)5]·THF (2) in high yield. Experimental results show that sodium/potassium complexes 1 and 2 are efficient catalysts for the ring-opening polymerization of lactides. Furthermore, complexes 1 and 2 have slight isotactic selectivity for the ring-opening polymerization of rac-lactide.