Atom-transfer radical polymerization by a recycable iron-amine catalyst

A trinuclear iron catalyst shown above is found to be a good catalyst for well-controlled atom-transfer radical polymerization of styrene. The formed polystyrene has a terminal chloride; in fact, post-polymerization with MMA smoothly takes place. The iron species can be removed from the formed polystyrene by precipitation of the polymer from methanol. The iron species can be recovered from the solution quantitatively; ¹H NMR spectrum of the recovered iron complex is identical with that of the initial iron compound. The recovered iron catalyst can be used for five repeated experiments of polymerization followed by catalyst recycle.