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Keywords:

  • Ruthenium;
  • Tungsten;
  • Green chemistry;
  • Polyoxometalates;
  • Oxidation

Abstract

A ruthenium complex, KNa[Ru2(C6H6)2(CH3COO)6] (Ru-KNa), and its polyoxotungstate derivative, Na6[{Ru(C6H6)}2W8O28(OH)2]·16H2O (Ru-Na), have been successfully isolated from routine synthetic reactions and characterized by X-ray single-crystal structure analysis, IR spectroscopy and elemental analysis. A remarkable aspect of Ru-KNa is that it has two ligand types, benzene and acetate, and the acetate ligands are connected exclusively by a central Na cation to form a dimeric sandwich-type structure, which is further connected by K cations to construct the 3D structures. Based on complex Ru-KNa, the compound Ru-Na was synthesized, and it consists of two {Ru(C6H6)} units linked to a [W8O28(OH)2]10– fragment by three Ru–O(W) bonds to result in an assembly with idealized C2 symmetry in which the polyanions form 3D structures by the connection of Na chains. Subsequently, the compound Ru-Na was anchored on (3-aminopropyl)triethoxysilane (apts) modified SBA-15 to prepare the solid catalysts, which were characterized by powder XRD, N2 adsorption measurements and FTIR spectroscopy. Finally, the catalytic efficiency of Ru-Na was assessed in the oxidation of n-hexadecane with air without any additives and solvents. The results indicated that Ru-Na is a heterogeneous catalyst and exhibits higher catalytic activity than previously reported Ru-containing polyoxotungstates.