Electron Paramagnetic Resonance Investigation of Some 11-Tungstoruthenate(III) Polyoxoanions

• Published in: European Journal of Inorganic Chemistry Vol. 2009; no. 34; pp. 5211 - 5214
• Main Authors: Rong, Charles C., So, Hyunsoo, Pope, Michael T.
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2009; WILEY‐VCH Verlag
• Subjects: EPR spectroscopy; Ligand field parameters; Polyoxometalates; Ruthenium
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.200900578

EPR spectra of three Keggin structure polyoxotungstates containing ruthenium(III), [PW11O39Ru(L)]4– (L = H2O, pyridine, dimethyl sulfoxide), have been recorded at 77 K and yield details of the symmetry and ligand field parameters of the embedded low‐spin d5 ruthenium cation. The magnitudes of the g tensors and 99,101Ru hyperfine coupling constants of the dmso derivative show that the unpaired electron occupies a dxy‐type orbital as a result of the axial component of the ligand field with Δ(dxy – dxz,dyz) ≈ 6200 cm–1. A weak broad absorption in the electronic spectrum at ca. 5600 cm–1 is consistent with this interpretation. A smaller rhombic component imposed by the polytungstate ligand further splits the dxz and dyz orbitals (< 2000 cm–1). The orbital reduction factor k of the dmso complex (0.69) is significantly smaller than those for the aqua and pyridine derivatives (0.80, 0.83), and this implies that, as previously found for the RuII analog, the dmso ligand is S‐bonded in the RuIII complex.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) Analysis of the EPR spectra of three [PW11O39RuIII(L)]4– anions provides detailed descriptions of the axial and rhombic components of the ligand field imposed upon the Ru cation by the lacunary polytungstate structure.