title: Probing intermetallic coupling in dinuclear N-heterocyclic carbene ruthenium(II) complexes.
abstract: A series of bimetallic N-heterocyclic carbene (NHC) ruthenium(II) complexes were synthesized, which comprise two [RuCl(2)(cymene)(NHC)] units that are interlinked via the NHC nitrogens by alkyl chains of different length. Electrochemical characterization revealed two mutually dependent oxidation processes for the complex with a methylene linker, indicating moderate intramolecular electronic coupling of the two metal centers (class II system). The degree of coupling decreases rapidly upon increasing the number of CH(2) units in the linker and provides essentially decoupled class I species when propylene or butylene linkers are used. Electrochemical analyses combined with structural investigations suggest a through-bond electronic coupling. Replacement of the alkyl linker with a p-phenylene group afforded cyclometalated complexes, which were considerably less stable. The electronic coupling in the methylene-linked complex and the relatively robust NHC-ruthenium bond may provide access to species that are switchable on the molecular scale.
authors.affiliation: Department of Chemistry, University of Fribourg, Chemin du Musee 9, CH-1700 Fribourg, Switzerland.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Mercs
authors.forename: Antonia
authors.initials: A
authors.lastname: Neels
authors.forename: Helen
authors.initials: H
authors.lastname: Stoeckli-Evans
authors.forename: Martin
authors.initials: M
authors.lastname: Albrecht
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C030011:carbene; D012428:Ruthenium; D008697:Methane