title: Simultaneous bridge-localized and mixed-valence character in diruthenium radical cations featuring diethynylaromatic bridging ligands.
abstract: A series of bimetallic ruthenium complexes [{Ru(dppe)Cp*}(2)(μ-C≡CArC≡C)] featuring diethynylaromatic bridging ligands (Ar = 1,4-phenylene, 1,4-naphthylene, 9,10-anthrylene) have been prepared and some representative molecular structures determined. A combination of UV-vis-NIR and IR spectroelectrochemical methods and density functional theory (DFT) have been used to demonstrate that one-electron oxidation of compounds [{Ru(dppe)Cp*}(2)(μ-C≡CArC≡C)](HC≡CArC≡CH = 1,4-diethynylbenzene; 1,4-diethynyl-2,5-dimethoxybenzene; 1,4-diethynylnaphthalene; 9,10-diethynylanthracene) yields solutions containing radical cations that exhibit characteristics of both oxidation of the diethynylaromatic portion of the bridge, and a mixed-valence state. The simultaneous population of bridge-oxidized and mixed-valence states is likely related to a number of factors, including orientation of the plane of the aromatic portion of the bridging ligand with respect to the metal d-orbitals of appropriate π-symmetry.
authors.affiliation: Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Fox
authors.forename: Boris
authors.initials: B
authors.lastname: Le Guennic
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Roberts
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Brue
authors.forename: Dmitry S
authors.initials: DS
authors.lastname: Yufit
authors.forename: Judith A K
authors.initials: JA
authors.lastname: Howard
authors.forename: Gabriele
authors.initials: G
authors.lastname: Manca
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Halet
authors.forename: František
authors.initials: F
authors.lastname: Hartl
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Low
mesh_terms: D002412:Cations / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D002412:Cations; D005609:Free Radicals; D006841:Hydrocarbons, Aromatic; D008024:Ligands; D009942:Organometallic Compounds; D012428:Ruthenium