Linking Metallacycle Transfer with Ring‐Opening Metathesis to Generate Polyacetylenes of Unprecedented Structure

Abstract A hafnium‐based bicyclic precursor ( COT‐2B‐Hf ) has been prepared that enables tandem Hf/E metallacycle transfer (E = main group element) and the ring‐opening metathesis polymerization (ROMP) of cyclooctatetraene (COT) units to generate a new family of structurally unique polyacetylenes. Highlights from this work include a tellurophene‐grafted polyacetylene, poly‐COT‐2B‐Te , and a polyacetylene with unsaturated vinyl side chains, poly‐COT‐2B‐vinyl . The resulting polymers can be processed into films that yield optical band gaps as low as 1.6 eV, representing promising new architectures for the optoelectronics community.