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, [SiW11O39RuIII(Py)]5− |
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| Authors: | Prof?Dr Masahiro Sadakane Sachie Moroi Yoshifumi Iimuro Dr Natalya Izarova Prof?Dr Ulrich Kortz Prof?Dr Shinjiro Hayakawa Kazuo Kato Dr Shuhei Ogo Dr Yusuke Ide Prof?Dr Wataru Ueda Prof?Dr Tsuneji Sano |
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| Institution: | 1. Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1‐4‐1 Kagamiyama, Higashi‐Hiroshima, 739‐8527 (Japan), Fax: (+81)?82‐424‐5494;2. PRESTO (Japan) Science and Technology Agency (JST), 4‐1‐8 Honcho, Kawaguchi, Saitama, 332‐0012 (Japan);3. Catalysis Research Center, Hokkaido University, N‐21, W‐10, Sapporo, 001‐0021 (Japan);4. School of Engineering and Science, Jacobs University, P. O. Box 750561, 28725, Bremen (Germany);5. Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI), SPring‐8, 1‐1‐1 Kouto, Sayo, Hyogo, 679‐5198 (Japan) |
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| Abstract: | Ruthenium(III)‐substituted α‐Keggin‐type silicotungstates with pyridine‐based ligands, SiW11O39RuIII(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 SiW11O39RuIII(H2O)]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 1H NMR spectroscopy, elemental analysis, titration, and X‐ray absorption near‐edge structure (XANES) analysis (Ru K‐edge and L3‐edge). Single‐crystal X‐ray analysis of compounds 2 , 3 , and 4 revealed that RuIII 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 RuIII–Py was reversibly oxidized into the RuIV–Py derivative and reduced into the RuII–Py derivative. |
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| Keywords: | pi interactions polyanions redox chemistry ruthenium substituent effects |
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