Olefin metathesis catalyst bearing a chelating phosphine ligand

An improved synthetic procedure for the complex (SPY-5-34)-dichloro-(κ2(C,P)-diphenyl-(2-benzylidene)-phosphine)-(1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydro-imidazol-2-ylidene)-ruthenium (2) was elaborated and the title compound was tested as latent initiator in Ring Opening Metathesis Polymerization (ROMP) and as catalyst for Ring-Closing Metathesis (RCM) at elevated temperatures. While not particularly suited as latent initiator for ROMP, exhibiting a switching temperature of only 42 °C in the polymerization of a typical norbornene derivative, 2 shows an appealing performance in RCM of α,ω-dienes at higher temperatures.