Synthesis and characterization of new ruthenium-based olefin metathesis catalysts coordinated with bidentate Schiff-base ligands

A novel series of Schiff-base-substituted ruthenium carbene complexes have been prepared by the treatment of RuCl2(=CHPh)(PCy3)(2) with a variety of Schiff-base ligands as the thallium salts. Modification of the Schiff-base electronic and/or structural substituents allowed for the tuning of the complexes activities in olefin metathesis reactions. The structures of the complexes were unambiguously characterized by NMR studies and X-ray analysis. These newly prepared complexes are highly stable to air, moisture, and temperature and even exhibit catalytic activity in polar protic solvents.