Redox-Rich Spin-Spin-Coupled Semiquinoneruthenium Dimers with Intense Near-IR Absorption
DSpace at IIT Bombay
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Title |
Redox-Rich Spin-Spin-Coupled Semiquinoneruthenium Dimers with Intense Near-IR Absorption
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Creator |
KUNDU, T
SARKAR, B MONDAL, TK MOBIN, SM URBANOS, FA FIEDLER, J JIMENEZ-APARICIO, R KAIM, W LAHIRI, GK |
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Subject |
TRANSITION-METAL-COMPLEXES
NUCLEAR-MAGNETIC-RESONANCE DENSITY-FUNCTIONAL THEORY QUINONE-RELATED LIGANDS NON-INNOCENT LIGANDS MIXED-VALENCE RUTHENIUM COMPLEXES ELECTRONIC-PROPERTIES DIRUTHENIUM COMPLEXES CARBOXYLATE COMPOUNDS |
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Description |
Using the [RuCl(mu-tppz)ClRu](2+) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine] platform for bridging two o-quinone/catecholate two-step redox systems (unsubstituted, Q(n), or 3,5-ditert-butyl-substituted, DTBQ(n)), we have obtained the stable complexes [(Q(center dot-))Ru(II)Cl(mu-tppz)ClRuII(Q(center dot-))] (1) and the structurally characterized [(DTBQ(center dot-))Ru(II)Cl(mu-tppz)ClRu(II)(DTBQ(center dot-))] (2). The compounds exhibit mostly quinone-ligand-based redox activity within a narrow potential range, high-intensity near-IR absorptions (lambda(max) approximate to 920 nm; epsilon > 50 000 M(-1) cm(-1)), and variable intra- and intermolecular spin-spin interactions. Density functional theory calculations, electron paramagnetic resonance (EPR), and spectro-electrochemical results (UV-vis-near-IR region) for three one-electron-reduction and two one-electron-oxidation processes were used to probe the electronic structures of the systems in the various accessible valence states. EPR spectroscopy of the singly charged doublet species showed semiquinone-type response for 1(+), 2(+), and 2(-), while 1 exhibits more metal based spin, a consequence of the easier reduction of Q as compared to DTBQ, Comparison with the analogous redox series involving a more basic N-phenyhminoquinone ligand reveals significant differences related to the shifted redox potentials, different space requirements, and different interactions between the metals and the quinone-type ligands. As a result, the tppz bridge is reduced here only after full reduction of the terminal quinone ligands to their catecholate states.
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Publisher |
AMER CHEMICAL SOC
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Date |
2012-06-26T08:48:43Z
2012-06-26T08:48:43Z 2011 |
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Type |
Article
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Identifier |
INORGANIC CHEMISTRY,50(11)4753-4763
0020-1669 http://dx.doi.org/10.1021/ic102280q http://dspace.library.iitb.ac.in/jspui/handle/100/14222 |
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Language |
English
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