Kumada catalyst transfer polymerization (KCTP) is the state-of-the-art method to achieve chain-growth polymerization of conjugated monomers; however, the current mono-nuclear catalysts struggle to co-polymerize electronically diverse monomers. In this work, a dinuclear nickel catalyst is demonstrated to be an effective and versatile catalyst for KCTP. Namely, it is capable of polymerizing a range of monomer electronics, including an electron rich thiophene and an electron poor benzotriazole, to high molecular weights. The ability of the dinuclear catalyst to do so hinges on effective ring-walking regardless of monomer electronics. We investigate ring-walking through exploring polymerizations of donor-acceptor based monomers, as well as studies on the binding of the dinuclear complex to various arenes. Although mononuclear catalysts typically feature dominant metal-arene π-back bonding, in the case of our dinuclear catalysts we hypothesize the back bonding to be mitigated and balanced with arene-to-metal s-bonding. Thus, our work illuminates a new dimension to the design of general catalysts for KCTP.

Dinuclear catalysts for enhanced ring walking in Kumada catalyst transfer polymerization

ACS Fall 2021

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