title: Ruthenium metallacycles derived from 14-electron complexes. New insights into olefin metathesis intermediates.
abstract: Ruthenium(IV) metallacycles derived from both ethylene and propene are reported. The propene-derived metallacycles represent the first observed examples of substituted ruthenacyclobutanes and offer new insight into the preferred stereochemical orientation about metathesis intermediates. In addition, a metallacycle possessing an unsymmetrical N-heterocyclic carbene (NHC) ligand was prepared and investigated to ascertain the dynamics of the NHC relative to the metallacycle ring. Metallacycles investigated were found to possess exchange cross-peaks between the alpha- and beta-positions in the 2D NMR, indicating a dynamic structure. The implications of these results to the mechanism of ruthenium-catalyzed olefin metathesis are discussed.
authors.affiliation: Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Anna G
authors.initials: AG
authors.lastname: Wenzel
authors.forename: Robert H
authors.initials: RH
authors.lastname: Grubbs
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D004583:Electrons; D015394:Molecular Structure; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D000475:Alkenes; D012428:Ruthenium