A Chain‐Growth Mechanism for Conjugated Polymer Synthesis Facilitated by Dinuclear Complexes with Redox‐Active Ligands
Andrew J. King, Aleksandr V. Zhukhovitskiy
Abstract
Conjugated polymers are widely used in energy conversion and sensor applications, but their synthesis relies on imprecise step-growth or narrow-scope chain-growth methods, typically based on transition metal (TM)-catalyzed cross-coupling. Here we report that a dinickel complex with a redox-active naphthyridine diimine ligand accesses new chain-growth mechanistic manifolds for both donor and acceptor conjugated polymers, represented by poly(3-hexylthiophene), poly(2,3-bis(2-ethylhexyl)thienopyrazine), and poly(2-(2-octyldodecyl)benzotriazole). For the latter, our method is particularly effective: we achieve high degrees of polymerization (DP) (>100) with moderate dispersities (Đ) of ≈1.4. Mechanistic analysis supports a radical/radical anion chain-growth mechanism with organometallic intermediates instead of TM-catalyzed cross-couplings. Hence, our work develops new mechanisms for conjugated polymer synthesis and furnishes insights about the elementary reactivity of dinuclear complexes.