Sustainable Polymerization of Natural Lactones via Iron Catalysis: An Integrated Experimental and Computational Study

An earth-abundant Fe-(II)-based catalyst was employed for efficient and sustainable ring-opening polymerization of naturally occurring ε- and δ-lactones. High turnover frequencies (TOFs) and excellent control over the polymerization of δ-substituted δ-lactones demonstrate the catalyst's ability to process monomers traditionally considered challenging or poorly polymerizable. Density Functional Theory (DFT) calculations suggest the formation of dinuclear iron species and underscore the mechanistic complexity of the system, including a monomer-dependent variation in the rate-determining step.