Mechanistic Insight into Catalyst-Transfer Polymerization of Unusual Anion-Radical Naphthalene Diimide Monomers: An Observation of Ni(0) Intermediates

Ni-catalyzed polymerization of anion-radical complexes formed upon mixing of 2,6-bis(2-bromothien-5-yl)-naphthalene-1,4,5,8-tetracarboxylic-N,N'-bis(2-octyldodecyl) dii-mide and activated Zn powder was investigated. We provide experimental evidence that the polymerization involves the chain-growth mechanism and proceeds via Ni(0) complexes which were previously proposed to be key intermediates in other chain-growth catalyst-transfer polycondensations (CTPs), such as Kumada CTP of thiophenic monomers. DFT calculations predict a remarkable stability of the naphthalene diimide-based Ni(0) complexes. A plausible polymerization mechanism is proposed.