Copper(II) complexes containing N,N′-bidentate N-substituted N-(pyridin-2-ylmethyl)amine: Synthesis, structure and application towards polymerization of rac-lactide

The reaction between [CuCl2 center dot 2H(2)O] and N,N'-bidentate N-(pyridin-2-ylmethyl)amines (L-n = L-A-L-E) in methanol yielded new Cu(II) complexes; namely mononuclear [LACuCl2] and dinuclear [LnCu(mu-Cl)Cl](2) (L-n = L-B-L-E) complexes, respectively. Monomeric [LACuCl2] showed a distorted square planar geometry around copper metal based on X-ray crystallography. The dimeric [LnCu(mu-Cl)Cl](2) (L-n = L-B-L-E) had a chloro-bridged 5-coordinated and a distorted square pyramidal geometry around the Cu(II) center. The range of Cu center dot center dot center dot Cu' distance was 3.3238(6)-3.593(2) angstrom in [LnCu(mu-Cl)Cl](2) (L-n = L-B-L-E). The Cu(II)-alkoxy derivatives, generated in situ, of these synthesized Cu(II) complexes have shown moderate activity towards the polymerization of rac-lactide (rac-LA) and yielded hetero-enriched PLA. The steric hindrance and electronic effects has a great influence on the catalytic activity and stereoselectivity of initiators. (C) 2017 Elsevier Ltd. All rights reserved.