Ring-Opening Alkyne Metathesis Polymerization Catalyzed by a Bench-Stable Rhenium Complex

In the last quarter of a century, ring-opening alkene metathesis polymerization has revolutionized the ability to synthesize functional polymers. In comparison, current methods for ring-opening alkyne metathesis polymerization (ROAMP) remain constrained by a narrow scope of monomers and catalysts that are not user-friendly. Herein, we report that an air-stable d² Re(V) alkylidyne precatalyst complex mediates ROAMP in a controlled fashion, even tolerating free hydroxyl groups in the monomer. This polymerization exhibits excellent control, with up to 700 degrees of polymerization of nonyne monomers with a low to moderate molecular weight dispersity. The metal can be cleaved from the polymer chain by means of cross-metathesis with commercially available phenylacetylenes. Additionally, this polymerization shows living character, which enables the preparation of block copolymers. These results highlight the potential of Re(V)-mediated polymerizations to enable a broader use of ROAMP for the synthesis of functional macromolecules.