title: Ruthenium-Ruthenium-Bonded [Bis{corrolato-ruthenium(III)}]n(n=0, +1, -1) Complexes: Model Compounds for the Photosynthetic Special Pair.
abstract: We present herein the synthesis of three new bis(corrolato-ruthenium(III)) complexes containing unsupported Ru-Ru bonds and their characterization in different redox states. The1H NMR spectra of the bis(corrolato-ruthenium(III)) complexes displayed "normal" chemical shifts and the compounds proved to be EPR-silent. Crystallographic characterization of the dimers indicated Ru-Ru distances of 2.175 Å, consistent with a triple bond between the two ruthenium centers. All of the synthesized complexes undergo two successive reversible oxidations and a single reversible reduction. A combination of UV/Vis/NIR/EPR spectroelectrochemical studies and DFT calculations established the redox state distributions in these ruthenium-ruthenium-bonded dimers. Whereas reduction of the dimers is metal-based and leads to metal-metal-bonded mixed-valent RuII-RuIIIspecies, one-electron oxidation largely retains the RuIII-RuIIIsituation with the generation of metal-bound corrolato radicals. The present study thus concerns the first UV/Vis/NIR/EPR spectroelectrochemical characterization and DFT calculations of ruthenium-ruthenium-bonded rotationally ordered corrole dimers. The mean plane separation between the two corrole units in these dimers is around 3.543 Å, which is in close agreement to that in the "special pair" in chlorophyll. Oxidation of these ruthenium-ruthenium-bonded dimers gives rise to two new electronic absorption bands in the NIR region (similar to those of the special pair), which have apparently not been mentioned/observed in earlier reports on ruthenium-ruthenium-bonded corrole dimers. These bands mainly originate from inter-corrole transitions.
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Khordha, 752050, India.|Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, India.
authors.forename: Woormileela
authors.initials: W
authors.lastname: Sinha
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sommer
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.
authors.forename: Lara
authors.initials: L
authors.lastname: Hettmanczyk
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Khordha, 752050, India.|Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, India.
authors.forename: Bratati
authors.initials: B
authors.lastname: Patra
authors.affiliation: Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550, Stuttgart, Germany.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Filippou
authors.affiliation: Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.
authors.forename: Biprajit
authors.initials: B
authors.lastname: Sarkar
authors.affiliation: School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, Khordha, 752050, India.|Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, India.
authors.forename: Sanjib
authors.initials: S
authors.lastname: Kar
keywords: EPR spectroscopy; density functional calculations; ruthenium corrole; ruthenium-ruthenium bond; spectroelectrochemistry