Stabilization of high-valence ruthenium with silicotungstate ligands: preparation, structural characterization, and redox studies of ruthenium(III)-substituted α-Keggin-type silicotungstates with pyridine ligands, [SiW11O39Ru(III)(Py)]5-.
Ruthenium(III)-substituted α-Keggin-type silicotungstates with pyridine-based ligands, [SiW(11)O(39)Ru(III)(Py)](5-), (Py: pyridine (1), 4-pyridine-carboxylic acid (2), 4,4'-bipyridine (3), 4-pyridine-acetamide (4), and 4-pyridine-methanol (5)) were prepared by reacting [SiW(11)O(39)Ru(III)(H(2)O)](5-) with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and (1)H NMR spectroscopy, elemental analysis, titration, and X-ray absorption near-edge structure (XANES) analysis (Ru K-edge and L(3)-edge). Single-crystal X-ray analysis of compounds 2, 3, and 4 revealed that Ru(III) was incorporated in the α-Keggin framework and was coordinated by pyridine derivatives through a Ru-N bond. In the solid state, compounds 2 and 3 formed a dimer through π-π interaction of the pyridine moieties, whereas they existed as monomers in solution. CV indicated that the incorporated Ru(III)-Py was reversibly oxidized into the Ru(IV)-Py derivative and reduced into the Ru(II)-Py derivative.
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527 Japan. sadakane09@hiroshima-u.ac.jp
Masahiro
M
Sadakane
Sachie
S
Moroi
Yoshifumi
Y
Iimuro
Natalya
N
Izarova
Ulrich
U
Kortz
Shinjiro
S
Hayakawa
Kazuo
K
Kato
Shuhei
S
Ogo
Yusuke
Y
Ide
Wataru
W
Ueda
Tsuneji
T
Sano