Controlled living ring-opening metathesis polymerization with a ruthenium indenylidene initiator

A study was conducted to demonstrate the synthesis, characterization, and living ring-opening metathesis polymerization (ROMP), with the highly active and rapidly initiating ruthenium (Ru)-indenyldene complex M3. The ruthenium (Ru)-indenyldene complex M3 enabled the synthesis of monodisperse homopolymers and block polymers. The complex was prepared from M2, which was stirred with excess pyridine under inert atmosphere of argon for 30 minutes at room temperature. Crystallization was carried out in a Schlenk-tube under inert conditions, along with a solution of M3 in dichloro-methane layered with pentane afforded well-crystallized material. Test polymerizations were conducted, with a series of monomers, to evaluate the applicability of M3 in living ROMP. It was observed that the color of the reaction mixture turned from brown to yellow, indicating a rapid initiation of M3, after the addition of the monomer.