The Interplay of ATRP, OMRP and CCT in Iron-Mediated Controlled Radical Polymerization

Metal-mediated controlled radical polymerization (CRP) is an indispensable tool for the construction of both simple and complicated macromolecules, decorated with an array of functional groups. Whilst this chemistry is dominated by copper, the use of iron complexes as mediators of CRP is becoming increasingly common; not least due to the very low cost of iron and the reduced intensity of its visible absorption spectrum. As a result, significant research effort has been concentrated on the study of iron complexes as catalysts for CRP, which has led to the observation that iron-mediated CRP reactions can be quite complex. They are proposed to be involved in a range of different equilibria, including atom transfer radical polymerization (ATRP), organometallic-mediated radical polymerization (OMRP) and catalytic chain transfer (CCT). An introduction to these equilibria, as well as a discussion of their interplay, particularly with reference to iron-mediated CRP reactions, is provided herein.