%0 Journal Article %1 Das.2009c %A Das, Atanu Kumar %A Sarkar, Biprajit %A Fiedler, Jan %A Zalis, Stanislav %A Hartenbach, Ingo %A Strobel, Sabine %A Lahiri, Goutam Kumar %A Kaim, Wolfgang. %D 2009 %J Journal of the American Chemical Society %K bridged center crystal dinuclear;redox electrochem electronic five iminoquinone prepn pyridylpyrazine redox ruthenium spectroelectrochem;ruthenium structure system %N 25 %P 8895--8902 %R 10.1021/ja901746x %T A Five-Center Redox System: Molecular Coupling of Two Noninnocent Imino-o-benzoquinonato-Ruthenium Functions through a p Acceptor Bridge %V 131 %X Combining the concepts of non-innocent behavior of metal/ligand entities and the coupling of redox-active moieties via an electronically mediating bridge led to the synthesis and the structural, electrochem., and spectroscopic characterization of [Cl(Q)Ru(m-tppz)Ru(Q)Cl]n where Qo is 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone and tppzo is 2,3,5,6-tetrakis(2-pyridyl)pyrazine, the available oxidn. states being RuII,III,IV, Qo,·-,2-, and tppzo,·-,2-. One-electron transfer steps between the n = (2-) and (4+) states were studied by cyclic voltammetry, EPR, UV-visible-NIR spectroelectrochem. for the structurally characterized anti isomer of [Cl(Q)Ru(m-tppz)Ru(Q)Cl](PF6)2, [2(PF6)2], the only configuration obtained. The combined studies reveal that 22+ is best described as [Cl(Q·-)RuIII(m-tppzo)RuIII(Q·-)Cl]2+ with antiferromagnetic coupling between the Ru(III) and the iminosemiquinone components at each end. A metal-based spin is evident from large g factor anisotropy (EPR) and an intense intervalence absorption band at 1850 nm in the near-IR (NIR) suggest that oxidn. occurs at both iminosemiquinones to yield two RuII,III-bonded quinones, implying redox-induced electron transfer. Redn. takes place stepwise at the metal centers yielding iminosemiquinone complexes of RuIII,II as evident from radical complex EPR spectra with small 99,101Ru hyperfine contributions. After complete metal redn. to Ru(II) the bridging ligand tppz is being reduced stepwise as apparent from typical NIR absorption bands around 1000 nm and from small g anisotropy of the monoanion [Cl(Q·-)RuII(m-tppz·-)RuII(Q·-)Cl]-. A structure-based DFT calcn. confirms the Ru-Cl character of the HOMO and the iminoquinone-dominated LUMO and illustrates the orbital interaction pattern of the five electron transfer active components in this new system. [on SciFinder(R)]

@article{Das.2009c, abstract = {Combining the concepts of non-innocent behavior of metal/ligand entities and the coupling of redox-active moieties via an electronically mediating bridge led to the synthesis and the structural, electrochem., and spectroscopic characterization of [Cl(Q)Ru(\textgreek{m}-tppz)Ru(Q)Cl]n where Qo is 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone and tppzo is 2,3,5,6-tetrakis(2-pyridyl)pyrazine, the available oxidn. states being RuII,III,IV, Qo,·-,2-, and tppzo,·-,2-. One-electron transfer steps between the n = (2-) and (4+) states were studied by cyclic voltammetry, EPR, UV-visible-NIR spectroelectrochem. for the structurally characterized anti isomer of [Cl(Q)Ru(\textgreek{m}-tppz)Ru(Q)Cl](PF6)2, [2(PF6)2], the only configuration obtained. The combined studies reveal that 22+ is best described as [Cl(Q·-)RuIII(\textgreek{m}-tppzo)RuIII(Q·-)Cl]2+ with antiferromagnetic coupling between the Ru(III) and the iminosemiquinone components at each end. A metal-based spin is evident from large g factor anisotropy (EPR) and an intense intervalence absorption band at 1850 nm in the near-IR (NIR) suggest that oxidn. occurs at both iminosemiquinones to yield two RuII,III-bonded quinones, implying redox-induced electron transfer. Redn. takes place stepwise at the metal centers yielding iminosemiquinone complexes of RuIII,II as evident from radical complex EPR spectra with small 99,101Ru hyperfine contributions. After complete metal redn. to Ru(II) the bridging ligand tppz is being reduced stepwise as apparent from typical NIR absorption bands around 1000 nm and from small g anisotropy of the monoanion [Cl(Q·-)RuII(\textgreek{m}-tppz·-)RuII(Q·-)Cl]-. A structure-based DFT calcn. confirms the Ru-Cl character of the HOMO and the iminoquinone-dominated LUMO and illustrates the orbital interaction pattern of the five electron transfer active components in this new system. [on SciFinder(R)]}, added-at = {2019-07-15T13:41:23.000+0200}, author = {Das, Atanu Kumar and Sarkar, Biprajit and Fiedler, Jan and Zalis, Stanislav and Hartenbach, Ingo and Strobel, Sabine and Lahiri, Goutam Kumar and Kaim, Wolfgang.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/23c94376f969f53b04ee1c9a0eb52e4c8/b_schwederski}, doi = {10.1021/ja901746x}, interhash = {b09be86830c91118da66956b4a1a3da2}, intrahash = {3c94376f969f53b04ee1c9a0eb52e4c8}, issn = {0002-7863}, journal = {Journal of the American Chemical Society}, keywords = {bridged center crystal dinuclear;redox electrochem electronic five iminoquinone prepn pyridylpyrazine redox ruthenium spectroelectrochem;ruthenium structure system}, number = 25, pages = {8895--8902}, timestamp = {2019-07-15T11:42:10.000+0200}, title = {A Five-Center Redox System: Molecular Coupling of Two Noninnocent Imino-o-benzoquinonato-Ruthenium Functions through a \textgreek{p} Acceptor Bridge}, volume = 131, year = 2009 }