TY - JOUR
T1 - Correspondence of Ru IIIRu II and Ru IVRu III mixed valent states in a small dinuclear complex
AU - Agarwala, Hemlata
AU - Scherer, Thomas Michael
AU - Maji, Somnath
AU - Mondal, Tapan Kumar
AU - Mobin, Shaikh M.
AU - Fiedler, Jan
AU - Urbanos, Francisco A.
AU - Jiménez-Aparicio, Reyes
AU - Kaim, Wolfgang
AU - Lahiri, Goutam Kumar
PY - 2012/4/27
Y1 - 2012/4/27
N2 - The diruthenium(III) compound [(μ-oxa){Ru(acac) 2} 2] [1, oxa 2-=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 1â2C 7H 8 revealed an intramolecular metal-metal distance of 5.433 Å 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 (K c=10 5.9) with broad NIR absorption bands (Îμ ca. 2000M -1cm -1) and maxima at 1800 (1 -) and 1500 nm (1 +). TD-DFT calculations support a Ru IIIRu II formulation for 1 - with a doublet ground state. The 1 + ion (Ru IVRu III) was calculated with an S=3/2 ground state and the doublet state higher in energy (ÎE=694.6 cm -1). The Mulliken spin density calculations showed little participation of the ligand bridge in the spin accommodation for all paramagnetic species [(μ-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 Ru IIIRu II (4d 5/4d 6) system 1 -, the Ru IVRu III (4d 4/4d 5) form 1 + exhibited extended absorbance over the UV/Vis/NIR range.
AB - The diruthenium(III) compound [(μ-oxa){Ru(acac) 2} 2] [1, oxa 2-=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 1â2C 7H 8 revealed an intramolecular metal-metal distance of 5.433 Å 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 (K c=10 5.9) with broad NIR absorption bands (Îμ ca. 2000M -1cm -1) and maxima at 1800 (1 -) and 1500 nm (1 +). TD-DFT calculations support a Ru IIIRu II formulation for 1 - with a doublet ground state. The 1 + ion (Ru IVRu III) was calculated with an S=3/2 ground state and the doublet state higher in energy (ÎE=694.6 cm -1). The Mulliken spin density calculations showed little participation of the ligand bridge in the spin accommodation for all paramagnetic species [(μ-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 Ru IIIRu II (4d 5/4d 6) system 1 -, the Ru IVRu III (4d 4/4d 5) form 1 + exhibited extended absorbance over the UV/Vis/NIR range.
KW - density functional calculations
KW - EPR spectroscopy
KW - magnetic properties
KW - mixed-valent compounds
KW - ruthenium
KW - spectroelectrochemistry
UR - http://www.scopus.com/inward/record.url?scp=84859915653&partnerID=8YFLogxK
U2 - 10.1002/chem.201103618
DO - 10.1002/chem.201103618
M3 - Article
AN - SCOPUS:84859915653
SN - 0947-6539
VL - 18
SP - 5667
EP - 5675
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 18
ER -