%0 Journal Article %1 Chanda.2004 %A Chanda, Nripen %A Sarkar, Biprajit %A Kar, Sanjib %A Fiedler, Jan %A Kaim, Wolfgang %A Lahiri, Goutam Kumar. %D 2004 %J Inorganic Chemistry %K complex complex;pyridylbenzimidazole dinuclear electrochem prepn prepn;pyridylbenzoxazole prepn;pyridylbenzthiazole prepn;ruthenium pyridylazole pyridylpyrazine redox ruthenium %N 16 %P 5128--5133 %R 10.1021/ic049605c %T Mixed Valence Aspects of Diruthenium Complexes (L)ClRu2(m-tppz)n+ Incorporating 2-(2-Pyridyl)azoles (L) as Ancillary Functions and 2,3,5,6-Tetrakis(2-pyridyl)pyrazine (Tppz) as Bis-Tridentate Bridging Ligand %V 43 %X Tppz 2,3,5,6-tetrakis(2-pyridyl)pyrazine-bridged complexes (L)ClRu2(m-tppz)n+ with structurally similar but electronically different ancillary ligands, 2-(2-pyridyl)azoles (L), were synthesized as diruthenium(II) species. Cyclic voltammetry, EPR of paramagnetic states, and UV-visible-NIR spectroelectrochem. show that the 1st two redn. processes occur at the tppz bridge and that oxidn. involves mainly the metal centers. The mixed valent intermediates from 1-electron oxidn. exhibit moderate comproportionation consts. 104 \textless Kc \textless 105 but appear to be valence-averaged according to the Hush criterion. Redox potentials, EPR, and UV-visible-NIR results show the effect of increasing donor strength of the ancillary ligands along the sequence L1 \textless L2 \textless L4 \flqq L3, L1 = 2-(2-pyridyl)benzoxazole, L2 = 2-(2-pyridyl)benzthiazole, L3 = 2-(2-pyridyl)benzimidazolate, L4 = 1-methyl-2-(2-pyridyl)-1H-benzimidazole. Whereas the mixed valent complexes with L1 and L2 remain EPR silent at 4 K, the analogs with L4 and L3 exhibit typical Ru(III) EPR signals, albeit with some noticeable ligand contribution in the case of the L3-contg. complex. Intervalence charge transfer (IVCT) bands were found in the visible spectrum for the complex with L3 but in the near-IR range (at $\sim$1500 nm) for the other systems. on SciFinder(R)

@article{Chanda.2004, abstract = {Tppz [2,3,5,6-tetrakis(2-pyridyl)pyrazine]-bridged complexes [{(L)ClRu}2(\textgreek{m}-tppz)]n+ with structurally similar but electronically different ancillary ligands, 2-(2-pyridyl)azoles (L), were synthesized as diruthenium(II) species. Cyclic voltammetry, EPR of paramagnetic states, and UV-visible-NIR spectroelectrochem. show that the 1st two redn. processes occur at the tppz bridge and that oxidn. involves mainly the metal centers. The mixed valent intermediates from 1-electron oxidn. exhibit moderate comproportionation consts. 104 {\textless} Kc {\textless} 105 but appear to be valence-averaged according to the Hush criterion. Redox potentials, EPR, and UV-visible-NIR results show the effect of increasing donor strength of the ancillary ligands along the sequence L1 {\textless} L2 {\textless} L4 {\flqq} L3, L1 = 2-(2-pyridyl)benzoxazole, L2 = 2-(2-pyridyl)benzthiazole, L3 = 2-(2-pyridyl)benzimidazolate, L4 = 1-methyl-2-(2-pyridyl)-1H-benzimidazole. Whereas the mixed valent complexes with L1 and L2 remain EPR silent at 4 K, the analogs with L4 and L3 exhibit typical Ru(III) EPR signals, albeit with some noticeable ligand contribution in the case of the L3-contg. complex. Intervalence charge transfer (IVCT) bands were found in the visible spectrum for the complex with L3 but in the near-IR range (at $\sim$1500 nm) for the other systems. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Chanda, Nripen and Sarkar, Biprajit and Kar, Sanjib and Fiedler, Jan and Kaim, Wolfgang and Lahiri, Goutam Kumar.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2561d6b2b6f999457ed73715b78e932f2/huebleriac}, doi = {10.1021/ic049605c}, interhash = {a29e3b4dc21c8fbe506d5cd59b74a2ae}, intrahash = {561d6b2b6f999457ed73715b78e932f2}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {complex complex;pyridylbenzimidazole dinuclear electrochem prepn prepn;pyridylbenzoxazole prepn;pyridylbenzthiazole prepn;ruthenium pyridylazole pyridylpyrazine redox ruthenium}, number = 16, pages = {5128--5133}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Mixed Valence Aspects of Diruthenium Complexes [{(L)ClRu}2(\textgreek{m}-tppz)]n+ Incorporating 2-(2-Pyridyl)azoles (L) as Ancillary Functions and 2,3,5,6-Tetrakis(2-pyridyl)pyrazine (Tppz) as Bis-Tridentate Bridging Ligand}, volume = 43, year = 2004 }