title: Experimental and theoretical studies of charge delocalization in biruthenium-alkynyl complexes bridged by thiophenes.
abstract: A series of binuclear ruthenium-alkynyl complexes that are bridged by thiophene groups (thiophene, bithiophene, and terthiophene) have been synthesized. All of these complexes have been well-characterized by NMR spectroscopy, X-ray diffraction, and elemental analysis. The electronic properties of these complexes have been examined by using cyclic voltammetry, UV/Vis/NIR and IR spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and density functional theory (DFT) calculations. Electrochemical results showed that the potential difference (ΔE) and comproportionation constant (Kc) decreased with increasing size of the thiophene bridging unit. The UV/Vis/NIR spectra and TDDFT calculations of the monocations indicated that the NIR transitions displayed aromatic bridging character. EPR studies of the mono-oxidized radical species further demonstrated that the unpaired electron/hole was delocalized over both metals and the bridging ligand and established significant participation in the ligand oxidation.
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Ou
authors.forename: Jianlong
authors.initials: J
authors.lastname: Xia
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Meng
authors.initials: M
authors.lastname: Xu
authors.forename: Jun
authors.initials: J
authors.lastname: Yin
authors.forename: Guang-Ao
authors.initials: GA
authors.lastname: Yu
authors.forename: Sheng Hua
authors.initials: SH
authors.lastname: Liu
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004583:Electrons; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011789:Quantum Theory; D012428:Ruthenium / Q000737:chemistry*; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D013876:Thiophenes; D012428:Ruthenium
keywords: bridging ligands; radicals; redox chemistry; ruthenium; thiophenes