title: Notable differences between oxidized diruthenium complexes bridged by four isomeric diethynyl benzodithiophene ligands.
abstract: Four new diruthenium complexes [{(η(5)-C5Me5)Ru(dppe)}2(μ-C[triple bond, length as m-dash]C-L-C[triple bond, length as m-dash]C)] featuring different bridging isomeric diethynyl benzodithiophenes viz. L = benzo[1,2-b;4,5-b']dithiophene (complex ), benzo[2,1-b;4,5-b']dithiophene (complex ), benzo[1,2-b;3,4-b']dithiophene (complex ) and benzo[1,2-b;4,3-b']dithiophene (complex ), were synthesized and characterized by molecular spectroscopic and crystallographic methods. The subtle changes in the molecular structure introduced by the diethynyl benzodithiophene isomers have a notable impact on the stability of the oxidized complexes and their absorption characteristics in the visible-NIR and IR spectral domains. Electronic properties of stable oxidized complexes [](n+) and [](n+) (n = 1, 2) were investigated by cyclic voltammetry, UV-vis-NIR and IR spectroelectrochemistry as well as DFT and TDDFT calculations. The results document the largely bridge-localized character of the oxidation of parents and . Cations [](+) and [](+) are too unstable at ambient temperature to afford their unambiguous characterization. UV-vis-NIR absorption spectral data combined with TDDFT calculations (BLYP35) reveal that the broad electronic absorption of [](+) and [](+) in the NIR region has a mixed intraligand π-π* and MLCT character, with similar contribution from their spin-delocalized trans and cis conformers. A spin-localized (mixed-valence) rotamer was only observed for [](+) at ambient temperature as a minor component on the time scale of IR spectroscopy.
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China. chshliu@mail.ccnu.edu.cn and College of Chemistry and Material Science, Hengyang Normal University, Hengyang, Hunan 421008, P. R. China.
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Ou
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China. chshliu@mail.ccnu.edu.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Material Science, Hengyang Normal University, Hengyang, Hunan 421008, P. R. China and Key Laboratory of Functional Organometallic Materials of Hunan Province College, Hengyang Normal University, Hengyang, Hunan 421008, P. R. China.
authors.forename: Fuxing
authors.initials: F
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Material Science, Hengyang Normal University, Hengyang, Hunan 421008, P. R. China and Key Laboratory of Functional Organometallic Materials of Hunan Province College, Hengyang Normal University, Hengyang, Hunan 421008, P. R. China.
authors.forename: Daizhi
authors.initials: D
authors.lastname: Kuang
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK. f.hartl@readig.ac.uk.
authors.forename: František
authors.initials: F
authors.lastname: Hartl
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China. chshliu@mail.ccnu.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Rao
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China. chshliu@mail.ccnu.edu.cn.
authors.forename: Sheng Hua
authors.initials: SH
authors.lastname: Liu