The Effects of Binding Ligand Variation on the Nickel Catalyzed Externally Initiated Polymerization of 2‐Bromo‐3‐hexyl‐5‐iodothiophene

Abstract

The effects of binding ligand variation on the externally initiated Ni catalyzed polymerization of P3HT were investigated using a novel methodology allowing facile screening of ligands. P3HT was synthesized with >80% initiator incorporation for both mono‐ and bidentate phosphine ligands. Variation of the initiating aryl group demonstrated vastly superior results for o‐tolyl over p‐tolyl substituents.

Kumada chain-growth polycondensation as a universal method for synthesis of well-defined conjugated polymers

“…These indicate the presence of salient chain-transfer or termination, and (PPh 3 ) 2 Ni(Ph)Br is not as good as Ni(dppp)Cl 2 for controlling the polymerization. Luscombe et al synthesized various catalysts, (PPh 3 ) 2 Ni(Aryl)Br, and systematically studied the effect of the structure of the aryl group on the polymerization [38,39]. Significant chain transfer/termination was observed, and therefore the polymerization did not show living characteristics.…”

Kumada Catalyst‐Transfer Polycondensation: Mechanism, Opportunities, and Challenges

“…[43,44] An one-pot preparation of Ni-initiators supported by bidentate ligands was attempted by Doubina et al Nickel cyclooctadiene (Ni(cod) 2 ) was reacted with aryl halides followed by the addition of one equivalent of a bidentate ligand (dppf, dppe, or dppp), or of two equivalents of the monodentate ligand PPh 3 (Scheme 3c). [71] The idea was to utilize the high reactivity of Ni(cod) 2 toward aryl halides combined with the lower binding ability of cod to nickel compared to bidentate phosphorous ligands. However, an appreciable degree of Ar group incorporation into the polymer was achieved only for PPh 3 , while the use of the bidentate ligand dppp resulted in the KCTP-inert complex Ni(dppp) 2 .…”

Nickel(II) α‐Diimine Catalyst for Grignard Metathesis (GRIM) Polymerization

“…Yokozawa also reported a nickel‐mediated “living” polymerization of 2‐bromo‐5‐iodo‐3‐hexylthiophene to generate regioregular P3HT with well‐defined molecular weights and narrow polydispersity index 8. More recent work by Kiriy and coworkers,9–13 Luscombe and coworkers,14–17 McNeil,18–20 and Locklin and coworkers21 provided more insight into the mechanism of nickel‐mediated cross‐coupling polymerization of thiophene and other aryl halide monomers. All the reported nickel catalysts for polymerization of thiophenes are phosphine‐based complexes.…”