Syntheses,Structures And Properties Of Organic-inorganic Hybrid Ruthenium-containing Polyoxometalates

The ruthenium-containing polyoxometalates?RCPs?endow POMs with unique catalyticproperties due to the redox and catalytic properties of ruthenium.The RCPs have triggered widespread attention over the past few decades due to their wonderful catalysis towards the oxidation of various organic substrates,the reduction of carbon dioxide and water oxidation reaction.In this paper,we have successfully synthesized four different types of RCPs by self-assembly strategy of sodium tungstate,heteroatom ingredients to react with RuCl₃.The compounds presented here were well-characterized by single crystal X-ray diffraction,Powder X-ray diffraction,elemental analyses,IR spectra,UV-vis spectra and thermogravimetric analyses.Additionally,the ESI-MS,the electrochemical property and catalytic properties of some selected compounds were also investigated.1.An acetate-bridged Ru-substituted arsenotungstate:[H₂N?CH₃?₂]₁₄[As₄W₄₀O₁₄₀{Ru₂?CH₃CO-O?}₂]·22H₂O?1?,compound 1 represents the first example of acetate-bridged Ru-substituted POMs,in which four Ru atoms occupy all lacunary S2 sites of the crown-shaped polyanion[As₄W₄₀O₁₄₀]^28-and each Ru atom is coordinated by one As atom and fivem₂-O atoms including four from S2 site and one from the acetate ligand.Notably,the novel coordination pattern of Ru atom in polyoxometalates?POMs?chemistry has been presented unprecedentedly,which is the formation of Ru-As bond with the length of2.377?3?-2.387?3??.Particularly,1 has exhibited high efficiency,splendid selectivity and good recyclability for the oxidation of sulfides with hydrogen peroxide?H₂O₂?.It is worth mentioning that catalytic oxidation of various sulfides in the presence of 1 gave superior conversion and selectivity for sulfones in acetonitrile or sulfoxides in methanol.2.A Ru?dmso?₃²⁺-supported arsenotungstate:Na₆[As₄W₈O₄₀?Ru?dmso?₃?₄)]?OH?Cl·26H₂O?2?.Two edge-shared WO₆ octahedra connect with an AsO₄ tetrahedron by sharing corners,forming a trinuclear cluster{AsW₂O₁₃}.A{Ru?dmso?₃}²⁺moiety supported on the surface of the trinuclear cluster{AsW₂O₁₃}via two Ru?O?W bonds and one Ru?O?As bond,leading to a asymmetric unit{AsW₂O₁₃Ru?dmso?₃}.Four equal asymmetric units{AsW₂O₁₃Ru?dmso?₃}connect with each other by sharing corners,resulting in the polyanion 2.Additionally,the polyoxoanion of 2 can further give to a three-dimensional network bridged by Na⁺and Cl^?ions.The ESI-MS study indicated that the existence of the parent cluster in aqueous solution.3.A Ru?dmso?₃²⁺-supported heptamolybdate:Na₄[Mo₇O₂₄Ru?dmso?₃]·6.5H₂O?3?.The polyoxoanion of 3 contains a[Mo₇O₂₄]^6-stabilized by one[Ru?dmso?₃]²⁺fragment,in which the ruthenium center was in a trigonal antiprismatic coordination mode bound to three dmso moieties and the heptamolybdate via three Ru-S bonds and three Ru-O bonds,respectively.3 exhibits good catalytic activity for the oxidation of alcohols in acetonitrile.4.Aion-typeRCPsconstructedbypolyoxoanionsandRucomplexes:Na₄[Ru?L?₃]₄[SiW₁₂O₄₀]·17.5H₂O?L=Pyridine-2,5-dicarboxylate??4?.Compounds 4 is consisted of a saturated Keggin-type[SiW₁₂O₄₀]^6?unit and four dissociative{Ru?L?₃}complexes.And the[SiW₁₂O₄₀]^6?unit is associated with the{Ru?L?₃}complexes by electrostatic interaction.