Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2-Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues
| Autor: | Francisco A. Urbanos, Jan Fiedler, Shaikh M. Mobin, Tapan Kumar Mondal, Wolfgang Kaim, Reyes Jiménez-Aparicio, Dipanwita Das, Doyel Kumbhakar, Goutam Kumar Lahiri, Biprajit Sarkar |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Semiquinone
Transition-Metal-Complexes Paramagnetic Resonance Nuclear-Magnetic-Resonance Magnetic Properties Ionic bonding chemistry.chemical_element Density Functional Calculations Induced Electron-Transfer Photochemistry Catalysis Ruthenium Coordination complex law.invention Density-Functional Theory law Semiquinone Ligands Quinone Complexes Molecule Electron paramagnetic resonance Spectroelectrochemistry Diimine chemistry.chemical_classification Dinuclear Ruthenium Complexes Charge-Distribution Organic Chemistry General Chemistry Oxidation-State Crystallography chemistry Intramolecular force Structure Elucidation |
| Zdroj: | IndraStra Global. |
| ISSN: | 2381-3652 |
| Popis: | Coordination compounds [Ru(acac)(2)(Q)] (acac = acetylacetonate; Q = o-benzoquinone) were prepared as complexes 1 (Q = o-benzoquinone), 2 (Q = 3-methoxy-o-benzoquinone), 3 (Q = 4-methyl-o-benzoquinone), and 4 (Q = 3,5-di-tert-butyl-o-benzoquinone). The structures of 1 and 2 were determined to reveal a Ru(III)/o-benzosemiquinone formulation, supported by analysis of experimental data (spectroscopy, magnetism of 1) and by DFT calculations. The S = 1 ground state calculated for 1 stands in contrast to the spin-paired analogues with arylimino-o-benzosemiquinonato and diimino-o-benzoquinone ligands. The close contacts of about 5.3 angstrom possible between semiquinone O atoms of different molecules in the crystal allow for intermolecular spin-spin interactions and an overall complex magnetic behavior. One quasireversible oxidation and two reversible one-electron reductions yielded the corresponding molecular ions, which were characterized by UV-visible-NIR and EPR spectroelectrochemistry in terms of [Ru(III)(acac)(2)(Q(0))](+), [Ru(III)(acac)(2)(Q(2-))](-), and [Ru(II)(acac)(2)(Q(2-))](2-) descriptions in agreement with DFT results. The use of acceptor-substituted 1,2-dioxolenes resulted in the isolation of ionic species Na[Ru(acac)(2)(Q)] (Na(5); Q = 4-chloro-o-benzoquinone) and Na(6) (Q = 4-nitro-o-benzoquinone), which were similarly investigated as compounds 1-4. Magnetic susceptibility and EPR results confirm an S = 1/2 ground state based on ruthenium(III). The combined studies reveal a remarkable substituent sensitivity, and in comparison to recently analyzed Ru(acac)(2) complexes with o-benzoquinone monoimine and diimine ligands, the all-O-donor-containing new systems are distinguished by a qualitatively different metal-ligand interaction based on closer intermolecular radical-radical contacts and on weaker intramolecular d pi-pi* interactions. |
| Databáze: | OpenAIRE |
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