Ferrocene in Radical Coordination Polymerization of Vinyl Chloride: a DFT Study

Metal complexes have a variety of current applications, including radical-initiated polymerization in the presence of metallocenes, which form active centers of coordination chain propagation. Recently, only styrene and methyl methacrylate radical coordination polymerization have been studied. A DFT study of all potential elementary acts of the radical polymerization vinyl chloride in the presence of ferrocene demonstrates that growth radicals (R^•) are bound to a ferrocene cyclopentadienyl ligand to form a metal-centered radical (C₅H₅R)Fe^•Cp with a free vacancy on an iron atom. The sequential addition of growth radicals and monomers to intermediate (C₅H₅R)Fe^•Cp leads to the formation of the following coordination chain growth active centers types: (C₅H₅R)FeR(M)Cp, R₂(M)Fe^•Cp, and (R)M₂FeCp. The chain propagation proceeds in these active centers without radicals, leading to the formation of a regular “head-to-tail” polymer structure. Notably, this process occurs without chain termination and radicals, a characteristic that allows it to be described as radical coordination polymerization.