Ruthenium Olefin Metathesis Initiators Bearing Chelating Sulfoxide Ligands

New ruthenium olefin metathesis initiators bearing sulfoxide moieties are described. The complexes were synthesized by the reaction of indenylidene ruthenium complexes Ind-II and Ind-II′ with different (2-vinyl)phenyl sulfoxides. These compounds show no catalytic activity at room temperature, but exhibit increased activity at elevated temperature. Preliminary studies on the influence of electronic and steric factors on the catalytic activity are presented.