Phenoxytriamine complexes of yttrium: synthesis, structure and use in the polymerization of lactide and ε-caprolactone

Reaction of the phenoxytriamine proligands 2,4-dimethyl-6-bis(2-(diethylamino)ethyl)aminomethlyphenol (HL1) and 2,4-di-tert-butyl-6-bis(2-(diethylamino)ethyl)aminomethylphenol (HL2) with Y[N(SiMe2H)2]3(THF)2 in pentane gave the momomeric complexes L1Y[N(SiMe2H)2]2 (1) and L2Y[N(SiMe2H)2]2 (2). X-Ray structural analysis of 2 shows a 5-coordinate yttrium center. The complexes 1 and 2 catalyze the ring opening polymerization of d-l-lactide and epsilon-caprolactone leading to narrow product polydispersities under mild conditions.