Redox-switchable olefin cross metathesis (CM) reactions and acyclic diene metathesis (ADMET) polymerizations

We show that redox-switchable catalysis may be used to control acyclic diene metathesis (ADMET) polymerizations and related reactions. A Ru(II) complex was found to display catalytic activities that were dependent on the oxidation state of a quinone-containing ligand. While the neutral form of the complex was found to catalyze ADMET polymerizations at rates that were commensurate with a commercially-available catalyst, significantly lower activities were observed when the complex was reduced. Using the rate differential, a series of ADMET polymerizations were modulated by alternately reducing and oxidizing the catalyst over time. A similar approach was also used to regulate the molecular weights of the polymers produced. Cross metathesis reactions and computational studies were performed in parallel to gain a deeper understanding of the underlying redox-switchable chemistry.