Polymerization of Allenes by Using an Iron(II) β‐Diketiminate Pre‐Catalyst to Generate High Mn Polymers. Issue 48 (16th July 2021)

• Record Type: Journal Article
• Authors: Woof, Callum R.; Durand, Derek J.; Webster, Ruth L.
• Is Part Of: Chemistry. Volume 27:Issue 48(2021)
• Page Start: 12335
• Page End: 12340
• Publication Date: 2021-07-16
• Subjects: allenes -- cycloaddition -- homogeneous catalysis -- iron -- polymers; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202101078
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Herein, we report an iron(II)‐catalyzed polymerization of arylallenes. This reaction proceeds rapidly at room temperature in the presence of a hydride co‐catalyst to generate polymers of weight up to M n =189 000 Da. We have determined the polymer structure and chain length for a range of monomers through a combination of NMR, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) analysis. Mechanistically, we postulate that the co‐catalyst does not react to form an iron(II) hydride in situ, but instead the chain growth is proceeding via a reactive Fe(III) species. We have also performed kinetic and isotopic experiments to further our understanding. The formation of a highly unusual 1, 3‐substituted cyclobutane side‐product is also investigated. Abstract : A rare example of transition metal‐catalyzed polymerization of aryl allenes is presented. Reactions are mild and generate very high M n polymers with narrow polydispersity by using a well‐defined Fe(II) pre‐catalyst and a hydride additive. [2+2] cycloaddition to form cyclobutanes is also viable using the same catalytic system.