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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/3689

Title: A new coordination mode of the photometric reagent gilyoxalbis(2-hydroxyanil) (H(2)gbha): Bis-bidentate bridging by gbha(2-) in the redox series {(mu-gbha)[Ru(acac)(2)](2)}(n) (n =-2,-1, 0,+1,+2), including a radical-bridged diruthenium(III) and a Ru-III/Ru-IV intermediate
Authors: KAR, S
SARKAR, B
GHUMAAN, S
ROY, D
URBANOS, FA
FIEDLER, J
SUNOJ, RB
JIMENEZ-APARICIO, R
KAIM, W
LAHIRI, GK
Keywords: spectroelectrochemical properties
oxidation-state
dinuclear ruthenium(iii)
molecular-structure
crystal-structure
complexes
ligand
acetylacetonate
chemistry
epr
Issue Date: 2005
Publisher: AMER CHEMICAL SOC
Citation: INORGANIC CHEMISTRY, 44(24), 8715-8722
Abstract: The bis-bidentate bridging function of gbha(2-) with N,O-/N,O- coordination was observed for the first time in the complex (mu-gbha)[Ru-III(acac)(2)](2) (1). Density functional theory calculations of 1 yield a triplet ground state with a large (Delta E > 6000 cm(-1)) singlet-triplet gap. Intermolecular antiferromagnetic coupling was observed (J approximate to -5.3 cm-1) for the solid. Complex 1 undergoes two one-electron reduction and two one-electron oxidation steps; the five redox forms {(mu-gbha)[Ru(acac)2]2}(n) (n = -2, -1, 0, +1, +2) were characterized by UV-vis-NIR spectroelectrochernistry (NIR = near infrared). The paramagnetic intermediates were also investigated by electron paramagnetic resonance (EPR) spectroscopy. The monoanion with a comproportionation constant K-c of 2.7 x 10(8) does not exhibit an NIR band for a Ru-III/Ru-II mixed-valent situation; it is best described as a 1,4-diazabutadiene radical anion containing ligand gbha(center dot 3-), which binds two ruthenium(III) centers. A Ru-III-type EPR spectrum with g(1) = 2.27, g(2) = 2.21, and g(3) = 1.73 is observed as a result of antiferromagnetic coupling between one Ru-III and the ligand radical. The EPR-active monocation (K-c = 1.7 x 10(6)) exhibits a broad (Delta v(1/2) = 2600 cm(-1)) intervalence charge-transfer band at 1800 nm, indicating a valence-averaged (Ru-3.5)(2) formulation (class III) with a tendency toward class II (borderline situation).
URI: http://dx.doi.org/10.1021/ic050950r
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3689
http://hdl.handle.net/10054/3689
ISSN: 0020-1669
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