%0 Journal Article %1 Kar.2005b %A Kar, Sanjib %A Sarkar, Biprajit %A Ghumaan, Sandeep %A Janardanan, Deepa %A van Slageren, Joris %A Fiedler, Jan %A Puranik, Vedavati G. %A Sunoj, Raghavan B. %A Kaim, Wolfgang %A Lahiri, Goutam Kumar. %D 2005 %J Chemistry - A European Journal %K acac bond bridged bridging charge complex complex;crystal complex;electrochem complex;hydrogen complex;mixed complex;ruthenium dinuclear dioxidobenzoquinonediimine electrochem ligand prepn redox ruthenium structure transfer valence %N 17 %P 4901--4911 %R 10.1002/chem.200500202 %T 2,5-Dioxido-1,4-benzoquinonediimine (H2L2-), a hydrogen-bonding noninnocent bridging ligand related to aminated topaquinone: Different oxidation state distributions in complexes [(bpy)2Ru2(m-H2L)]n (n = 0 , +, 2+, 3+, 4+) and [(acac)2Ru2(m-H2L)]m (m = 2-, -, 0, +, 2+) %V 11 %X The sym. dinuclear title compds. were isolated as diamagnetic [(bpy)2Ru(m-H2L)Ru(bpy)2](ClO4)2 (1-(ClO4)2) and as paramagnetic [(acac)2Ru(m-H2L)Ru(acac)2] (2) complexes (bpy = 2,2'-bipyridine; acac- = acetylacetonate; H2L = 2,5-dioxido-1,4-benzoquinonediimine). The crystal structure of 2·2H2O reveals an intricate H-bonding network: two symmetry-related mols. 2 are closely connected through two NH(H2L2-)···O-(acac-) interactions, while the O atoms of H2L2- of two such pairs are bridged by an (H2O)8 cluster at half-occupancy. The cluster consists of cyclic (H2O)6 arrangements with the remaining two exo-H2O mols. connecting two opposite sides of the cyclo-(H2O)6 cluster, and oxido O atoms forming H bonds with the mols. of 2. Weak antiferromagnetic coupling of the two Ru(III) centers in 2 was established by using SQUID magnetometry and EPR spectroscopy. Geometry optimization by DFT calcns. was carried out for 12+ and 2 in their singlet and triplet ground states, resp. The nature of low-energy electronic transitions was explored by using time-dependent DFT methods. Five redox states were reversibly accessible for each of the complexes; all odd-electron intermediates exhibit comproportionation consts. Kc \textgreater 108. UV-visible-NIR spectroelectrochem. and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidn.-state distribution. In general, the complexes 1n+ prefer the Ru(II) configuration with electron transfer occurring largely at the bridging ligand (m-H2Ln-), as evident from radical-type EPR spectra for 13+ and 1+. Higher metal oxidn. states (III, IV) appear to be favored by the complexes 2m; intense long-wavelength absorption bands and RuIII-type EPR signals suggest mixed-valent dimetal configurations of the paramagnetic intermediates 2+ and 2-. [on SciFinder(R)]

@article{Kar.2005b, abstract = {The sym. dinuclear title compds. were isolated as diamagnetic [(bpy)2Ru(\textgreek{m}-H2L)Ru(bpy)2](ClO4)2 (1-(ClO4)2) and as paramagnetic [(acac)2Ru(\textgreek{m}-H2L)Ru(acac)2] (2) complexes (bpy = 2,2'-bipyridine; acac- = acetylacetonate; H2L = 2,5-dioxido-1,4-benzoquinonediimine). The crystal structure of 2·2H2O reveals an intricate H-bonding network: two symmetry-related mols. 2 are closely connected through two NH(H2L2-)···O-(acac-) interactions, while the O atoms of H2L2- of two such pairs are bridged by an (H2O)8 cluster at half-occupancy. The cluster consists of cyclic (H2O)6 arrangements with the remaining two exo-H2O mols. connecting two opposite sides of the cyclo-(H2O)6 cluster, and oxido O atoms forming H bonds with the mols. of 2. Weak antiferromagnetic coupling of the two Ru(III) centers in 2 was established by using SQUID magnetometry and EPR spectroscopy. Geometry optimization by DFT calcns. was carried out for 12+ and 2 in their singlet and triplet ground states, resp. The nature of low-energy electronic transitions was explored by using time-dependent DFT methods. Five redox states were reversibly accessible for each of the complexes; all odd-electron intermediates exhibit comproportionation consts. Kc {\textgreater} 108. UV-visible-NIR spectroelectrochem. and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidn.-state distribution. In general, the complexes 1n+ prefer the Ru(II) configuration with electron transfer occurring largely at the bridging ligand (\textgreek{m}-H2Ln-), as evident from radical-type EPR spectra for 13+ and 1+. Higher metal oxidn. states (III, IV) appear to be favored by the complexes 2m; intense long-wavelength absorption bands and RuIII-type EPR signals suggest mixed-valent dimetal configurations of the paramagnetic intermediates 2+ and 2-. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Kar, Sanjib and Sarkar, Biprajit and Ghumaan, Sandeep and Janardanan, Deepa and {van Slageren}, Joris and Fiedler, Jan and Puranik, Vedavati G. and Sunoj, Raghavan B. and Kaim, Wolfgang and Lahiri, Goutam Kumar.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/26d18654a0b31288ec2e6ccc27d93f47e/huebleriac}, doi = {10.1002/chem.200500202}, interhash = {eb639de2f73e077c58726b27aa32e30a}, intrahash = {6d18654a0b31288ec2e6ccc27d93f47e}, issn = {0947-6539}, journal = {Chemistry - A European Journal}, keywords = {acac bond bridged bridging charge complex complex;crystal complex;electrochem complex;hydrogen complex;mixed complex;ruthenium dinuclear dioxidobenzoquinonediimine electrochem ligand prepn redox ruthenium structure transfer valence}, number = 17, pages = {4901--4911}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {2,5-Dioxido-1,4-benzoquinonediimine (H2L2-), a hydrogen-bonding noninnocent bridging ligand related to aminated topaquinone: Different oxidation state distributions in complexes [{(bpy)2Ru}2(\textgreek{m}-H2L)]n (n = 0 , +, 2+, 3+, 4+) and [{(acac)2Ru}2(\textgreek{m}-H2L)]m (m = 2-, -, 0, +, 2+)}, volume = 11, year = 2005 }