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

## TL;DR

A new rhenium-based catalyst enables controlled ring-opening alkyne metathesis polymerization with improved usability and versatility.

## Contribution

A bench-stable rhenium complex enables controlled ROAMP with tolerance for hydroxyl groups and living polymerization characteristics.

## Key findings

- The Re(V) complex allows controlled ROAMP with up to 700 degrees of polymerization and low dispersity.
- The catalyst tolerates hydroxyl groups in monomers and allows post-polymerization cleavage via cross-metathesis.
- The process exhibits living polymerization behavior, enabling block copolymer synthesis.

## Abstract

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.