Synthesis of High-molecular-weight Head-to-tail-type Poly(3-substituted-thiophene)s by Cross-coupling Polycondensation with [CpNiCl(NHC)] as a Catalyst

High-molecular-weight head-to-tail-type regioregular polythiophenes are synthesized by [CpNiCl(SIPr)]-catalyzed dehydrobrominative polycondensation. Polycondensation of 2-bromo-3-hexylthiophene at the C-H bond proceeds with an equimolar amount of TMPMgCl center dot LiCl and a catalytic amount of [CpNiCl(SIPr)] to afford the regioregular poly(3-hexylthiophene) (HT-P3HT) with up to M-w = 815000. A self-standing HT-P3HT film is obtained with the regioregular HT-P3HT of M-w = 414000, while the attempted formation of the corresponding film with lower-molecular-weight HT-P3HT (M-w = 38000) is unsuccessful.