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Correspondence of RuIIIRuII and RuIVRuIII Mixed Valent States in a Small Dinuclear Complex

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Title Correspondence of RuIIIRuII and RuIVRuIII Mixed Valent States in a Small Dinuclear Complex
 
Creator AGARWALA, H
SCHERER, TM
MAJI, S
MONDAL, TK
MOBIN, SM
FIEDLER, J
URBANOS, FA
JIMENEZ-APARICIO, R
KAIM, W
LAHIRI, GK
 
Subject density functional calculations
EPR spectroscopy
magnetic properties
mixed-valent compounds
ruthenium
spectroelectrochemistry
DENSITY-FUNCTIONAL THEORY
MAGNETIC-PROPERTIES
TETRANUCLEAR COMPLEXES
CARBOXYLATE COMPOUNDS
RUTHENIUM COMPLEXES
EXCITATION-ENERGIES
CRYSTAL-STRUCTURE
BRIDGING LIGANDS
OXIDATION-STATES
COORDINATION
 
Description The diruthenium(III) compound [(mu-oxa){Ru(acac)2}2] [1, oxa2-=oxamidato(2-), acac-=2,4-pentanedionato] exhibits an S=1 ground state with antiferromagnetic spin-spin coupling (J=-40 cm-1). The molecular structure in the crystal of 1.2?C7H8 revealed an intramolecular metalmetal distance of 5.433 angstrom and a notable asymmetry within the bridging ligand. Cyclic voltammetry and spectroelectrochemistry (EPR, UV/Vis/NIR) of the two-step reduction and of the two-step oxidation (irreversible second step) produced monocation and monoanion intermediates (Kc=105.9) with broad NIR absorption bands (e ca. 2000?M-1?cm-1) and maxima at 1800 (1-) and 1500 nm (1+). TD-DFT calculations support a RuIIIRuII formulation for 1- with a doublet ground state. The 1+ ion (RuIVRuIII) was calculated with an S=3/2 ground state and the doublet state higher in energy (?E=694.6 cm-1). The Mulliken spin density calculations showed little participation of the ligand bridge in the spin accommodation for all paramagnetic species [(mu-oxa){Ru(acac)2}2]n, n=+1, 0, -1, and, accordingly, the NIR absorptions were identified as metal-to-metal (intervalence) charge transfers. Whereas only one such NIR band was observed for the RuIIIRuII (4d5/4d6) system 1-, the RuIVRuIII (4d4/4d5) form 1+ exhibited extended absorbance over the UV/Vis/NIR range.
 
Publisher WILEY-V C H VERLAG GMBH
 
Date 2014-10-17T05:58:56Z
2014-10-17T05:58:56Z
2012
 
Type Article
 
Identifier CHEMISTRY-A EUROPEAN JOURNAL, 18(18)5667-5675
0947-6539
1521-3765
http://dx.doi.org/10.1002/chem.201103618
http://dspace.library.iitb.ac.in/jspui/handle/100/16127
 
Language en