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

0379012 - ÚFCH JH 2013 RIV DE eng J - Článek v odborném periodiku
Agarwala, H. - Scherer, T. M. - Maji, S. - Mondal, T. K. - Mobin, S. M. - Fiedler, Jan - Urbanos, F. A. - Jimenez-Aparicio, R. - Kaim, W. - Lahiri, G. K.
Correspondence of RuIIIRuII and RuIVRuIII Mixed Valent States in a Small Dinuclear Complex.
Chemistry - A European Journal. Roč. 18, č. 18 (2012), s. 5667-5675. ISSN 0947-6539. E-ISSN 1521-3765
Grant CEP: GA MŠMT(CZ) ME10124
Výzkumný záměr: CEZ:AV0Z40400503
Klíčová slova: density functional calculations * EPR spectroscopy * magnetic properties
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 5.831, rok: 2012

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.
Trvalý link: http://hdl.handle.net/11104/0210299