Ruthenium-Indenylidene Olefin Metathesis Catalyst with Enhanced Thermal Stability

Two new ruthenium complexes bearing a bidentate (kappa O-2, C)-isopropoxy- indenylidene ligand and a PPh3 (9) or PCy3 (10, Cy = cyclohexyl) ligand have been synthesized and fully characterized by H-1 and C-13 NMR spectroscopy and X-ray crystallography. Complex 10 displays a very high thermal stability with a half life of six days at 110 degrees C in [D-8] toluene. Complex 10 was evaluated in various ring-closing metathesis reactions and ring-opening metathesis polymerization of dicyclopentadiene, in which it showed a latent behavior with low activity at room temperature and high activity upon thermal activation.