Reusable and environmentally friendly ionic trinuclear iron complex catalyst for atom transfer radical polymerization.

Ionic iron complex [(Me(3)tacn)(2)Fe(2)Cl(3)](+)[(Me(3)tacn)FeCl(3)](-) (1), which is readily soluble in methanol, acted as a powerful catalyst in controlled radical polymerization of styrene and MMA, and showed promising features of removal from the resulting polymers and was reusable after recovery from the crude products.