Palladium-Catalyzed Chain-Growth Polycondensation of AB-type Monomers: High Catalyst Turnover and Polymerization Rates

Chain-growth catalyst-transfer polycondensations of AB-type monomers is a new and rapidly developing tool for the preparation of well-defined pi-conjugated (semiconducting) polymers for various optoelectronic applications. Herein, we report the Pd/PtBu3-catalyzed Negishi chain-growth polycondensation of AB-type monomers, which proceeds with unprecedented TONs of above 100 000 and TOFs of up to 280 s(-1). In contrast, related AA/BB-type step-growth polycondensation proceeds with two orders of magnitude lower TONs and TOFs. A similar trend was observed in Suzuki-type polycondensation. The key impact of the intramolecular (vs. intermolecular) catalyst-transfer process on both polymerization kinetics and catalyst lifetime has been revealed.