Synthesis, characterization of carbon-bridged Bis(phenolate) neodymium complexes and their catalytic activity for ring-opening polymerization of cyclic esters

Three carbon-bridged bis(phenolate) neodymium complexes, [(MBMP)2Nd(μ3–Cl)Li(THF)2Li(THF)] (1), [(MBBP)2Nd(μ3-Cl)Li(THF)2Li(THF)] (2) and [(THF)2Nd(EDBP)2Li(THF)] (3) have been synthesized by one-pot reaction of NdCl3 and LiCH2SiMe3 with 6,6′-methylenebis(2-tert-butyl-4-methylphenol) (MBMP-H2), 6,6′-methylenebis(2,4-di-tert-butylphenol) (MBBP-H2) or 6,6′-(ethane- 1,1-diyl)bis(2,4-di-tert-butylphenol) (EDBP-H2), respectively, in a molar ratio of 1:4:2. The definitive structures of complexes 2 and 3 were determined by X-ray diffraction studies. Experimental results show that 1–3 efficiently initiate the ring-opening polymerization (ROP) of ε-caprolactone and ROP of L-lactide.