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UV-vis-NIR and EPR characterisation of the redox series [MQ(3)](2+,+,0,-,2-), M=Ru or Os, and Q=o-quinone derivative

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Title UV-vis-NIR and EPR characterisation of the redox series [MQ(3)](2+,+,0,-,2-), M=Ru or Os, and Q=o-quinone derivative
 
Creator DAS, AK
HUBNER, R
SARKAR, B
FIEDLER, J
ZALIS, S
LAHIRI, GK
KAIM, W
 
Subject TRANSITION-METAL-COMPLEXES
DENSITY-FUNCTIONAL CALCULATIONS
ORDER REGULAR APPROXIMATION
ELECTRONIC-STRUCTURE
CATECHOLATE LIGANDS
SEMIQUINONE LIGANDS
CHARGE-DISTRIBUTION
OXIDATION-STATES
G-TENSORS
RUTHENIUM
 
Description The neutral title compounds with Q = 3,5-di-tert-butyl-o-quinone or 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone (Q(x)) were studied by UV-vis-NIR spectroelectrochemistry and by EPR spectroscopy in the case of the odd-electron monocation and monoanion intermediates. Supported by DFT and TD-DFT calculations, the results indicate stepwise electron removal from predominantly ligand-based delocalised MOs on oxidation whereas the stepwise electron uptake on reduction involves unoccupied MOs with considerably metal-ligand mixed character. In both cases, the strong near-infrared absorption of the neutral precursors diminishes. In comparison to the ruthenium series, the osmium analogues exhibit larger transition energies from enhanced MO splitting and a different EPR response due to the higher spin-orbit coupling. The main difference between the quinone (1(n), 2(n)) and corresponding monoiminoquinone systems (3(n), 4(n)) is the shift of about 0.6 V to lower potentials for the monoimino analogues. While the absorption features do not differ markedly, the EPR data reflect a higher degree of covalent bonding for the complexes with monoimino ligands.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2014-10-16T15:04:00Z
2014-10-16T15:04:00Z
2012
 
Type Article
 
Identifier DALTON TRANSACTIONS, 41(29)8913-8921
http://dx.doi.org/10.1039/c2dt30846k
http://dspace.library.iitb.ac.in/jspui/handle/100/15855
 
Language en