%0 Journal Article %1 Kundu.2010 %A Kundu, Tanaya %A Sarkar, Biprajit %A Mondal, Tapan Kumar %A Fiedler, Jan %A Mobin, Shaikh M. %A Kaim, Wolfgang %A Lahiri, Goutam Kumar. %D 2010 %J Inorganic Chemistry %K DFT complex complex;dinuclear crystal dinuclear electrochem electrochem;quinaldato electrochem;quinolinecarboxylato electronic picolinato prepn quinaldato quinolinecarboxylato ruthenium structure tetrakispyridylpyrazine %N 14 %P 6565--6574 %R 10.1021/ic100500p %T Carboxylate Tolerance of the Redox-Active Platform Ru(m-tppz)Run, where tppz = 2,3,5,6-Tetrakis(2-pyridyl)pyrazine, in the Electron-Transfer Series (L)ClRu(m-tppz)RuCl(L)n, n = 2+, +, 0, -, and 2-, with 2-Picolinato, Quinaldato, and 8-Quinolinecarboxylato Ligands (L-) %V 49 %X The neutral title complexes (L1-3)ClRuII(m-tppz)RuIICl(L1-3) tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine with L1 = 2-picolinate (1), L2 = 2-quinolinecarboxylate (quinaldate) (2) and with the hitherto little used L3 = 8-quinolinecarboxylate (3) were structurally characterized as approx. anti- (1 and 3) and syn-configured isomers (2) with L ligand N (1 and 3) or O atoms (2) trans to the pyrazine N atoms of tppz. In contrast to 1 and 2 with five-membered chelate rings, complex 3 (which is isomeric with 2) contains six-membered chelate rings. Each system 1-3 thus features a significantly different coordination situation, and all complexes exhibit a considerably distorted tppz bridge, including a twisted central pyrazine ring. In spite of this, double one-electron redn. of the bridge is always possible, as is evident from EPR and UV/visible spectroelectrochem. Two sep. (DE $\sim$ 0.4 V and Kc $\sim$ 107) 1-electron oxidns. occur on the metals, producing invariably EPR-silent (4 K) RuIIIRuII intermediates with moderately intense near-IR absorptions, ranging from 1500 to 1900 nm. IR spectroelectrochem. of the carboxylato carbonyl stretching bands did not result in any noticeable shift, in contrast to what was obsd. with dipyridyl ketones and related coligands. D. functional theory (DFT)/time-dependent DFT calcns. confirm the exptl. structures and explain the noted spectroscopic trends: destabilized and closer-spaced frontier orbitals for 3 over 2, with the comparison to 1 suggesting that the configuration is a major factor. Nevertheless, the rather unperturbed electronic structure of the Ru(m-tppz)Run entity, despite different coordination situations at the metal sites, is remarkable and suggests further use of this entity as a robust, carboxylate-tolerant redox-active platform in extended frameworks. on SciFinder(R)

@article{Kundu.2010, abstract = {The neutral title complexes [(L1-3)ClRuII(\textgreek{m}-tppz)RuIICl(L1-3)] [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine with L1 = 2-picolinate (1), L2 = 2-quinolinecarboxylate (quinaldate) (2) and with the hitherto little used L3 = 8-quinolinecarboxylate (3)] were structurally characterized as approx. anti- (1 and 3) and syn-configured isomers (2) with L ligand N (1 and 3) or O atoms (2) trans to the pyrazine N atoms of tppz. In contrast to 1 and 2 with five-membered chelate rings, complex 3 (which is isomeric with 2) contains six-membered chelate rings. Each system 1-3 thus features a significantly different coordination situation, and all complexes exhibit a considerably distorted tppz bridge, including a twisted central pyrazine ring. In spite of this, double one-electron redn. of the bridge is always possible, as is evident from EPR and UV/visible spectroelectrochem. Two sep. (\textgreek{D}E $\sim$ 0.4 V and Kc $\sim$ 107) 1-electron oxidns. occur on the metals, producing invariably EPR-silent (4 K) RuIIIRuII intermediates with moderately intense near-IR absorptions, ranging from 1500 to 1900 nm. IR spectroelectrochem. of the carboxylato carbonyl stretching bands did not result in any noticeable shift, in contrast to what was obsd. with dipyridyl ketones and related coligands. D. functional theory (DFT)/time-dependent DFT calcns. confirm the exptl. structures and explain the noted spectroscopic trends: destabilized and closer-spaced frontier orbitals for 3 over 2, with the comparison to 1 suggesting that the configuration is a major factor. Nevertheless, the rather unperturbed electronic structure of the [Ru(\textgreek{m}-tppz)Ru]n entity, despite different coordination situations at the metal sites, is remarkable and suggests further use of this entity as a robust, carboxylate-tolerant redox-active platform in extended frameworks. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Kundu, Tanaya and Sarkar, Biprajit and Mondal, Tapan Kumar and Fiedler, Jan and Mobin, Shaikh M. and Kaim, Wolfgang and Lahiri, Goutam Kumar.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/269d09befddee12ebe0844cb2911ae0ef/huebleriac}, doi = {10.1021/ic100500p}, interhash = {ce53dd1e5b734e7f31b9611cf636e468}, intrahash = {69d09befddee12ebe0844cb2911ae0ef}, issn = {0020-1669}, journal = {Inorganic Chemistry}, keywords = {DFT complex complex;dinuclear crystal dinuclear electrochem electrochem;quinaldato electrochem;quinolinecarboxylato electronic picolinato prepn quinaldato quinolinecarboxylato ruthenium structure tetrakispyridylpyrazine}, number = 14, pages = {6565--6574}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Carboxylate Tolerance of the Redox-Active Platform [Ru(\textgreek{m}-tppz)Ru]n, where tppz = 2,3,5,6-Tetrakis(2-pyridyl)pyrazine, in the Electron-Transfer Series [(L)ClRu(\textgreek{m}-tppz)RuCl(L)]n, n = 2+, +, 0, -, and 2-, with 2-Picolinato, Quinaldato, and 8-Quinolinecarboxylato Ligands (L-)}, volume = 49, year = 2010 }