Reversible‐Deactivation Radical Polymerization of Vinyl Acetate Mediated by Ligand Non‐Innocent Organometallic Tralen Complexes

A series of tralen‐based organometallic complexes incorporating zinc(II), calcium(II), and nickel(II) were synthesized and used for controlling the radical polymerization of vinyl acetate (VAc), N ‐vinylpyrrolidone (NVP), acrylonitrile (AN), and methyl acrylate (MA). The resulting polymerizations demonstrated living characteristics, including linear increases in molecular weight with monomer conversion, molecular weight matching the theoretical values, and the formation of block copolymers. The mechanism studies, supported by NMR spectrum, MALDI‐TOF MS data, and chain extension experiments, indicate that the control of polymerization is governed by a degenerative transfer pathway, with the reactive sites at the γ‐carbon of tropone moieties. The control experiment using EDTA to extract the metal ions from the polymer products confirmed that the polymer chain is bound to the ligand rather than the metal center. This establishes tralen as a non‐innocent ligand that participates in the radical deactivation process.