Alkali Metal Alkaline-Earth Metal Complexes of Various Amidophosphines having P, N, Chalcogen and Borane as Donor atoms/group – Syntheses, Structures and Ring-Opening Polymerization of Caprolactone

摘要

During the last decade, heavy alkaline-earth organometallic chemistry has emerged from obscurity to becoming a vibrant area of research, owing to a number of synthetic pathways that provide reliable access to these highly reactive target compounds. The complexes of heavy alkaline-earth metals were employed in various catalytic applications such as ring-opening polymerization of various cyclic esters, polymerization of styrene and dienes, and hydroamination and hydrophosphination reactions of alkenes and alkynes. Particularly, Group 2 metal complexes have been received considerable attention as initiators for the ROP of cyclic esters and some of them have demonstrated impressive results. Aliphatic polyesters are currently considered as alternatives to synthetic petrochemical-based polymers. Their biodegradable and biocompatible nature along with their mechanical and physical properties make them prospective thermoplastics with broad commercial applications such as single-use packaging materials, medical sutures and drug delivery systems. Ring-opening polymerization (ROP) of cyclic esters promoted by alkaline-earth & rare-earth metal initiators proved to be the most efficient way for preparing polyesters with controlled molecular weight and microstructure and narrow molecular-weight distribution. Therefore, the design and synthesis of new well-defined single-site catalysts that exhibits good activity, productivity and selectivity for cyclic ester polymerization is needed.