Synthesis, Structure And Properties Of Organic-Polyacid Charge-Transfer Compounds And Transition Metal-Polyoxometalate Complexes

A series of charge-transfer complexes exhibiting photochromic properities were synthesized and charactered by X-ray crystallography, IR, UV, diffusion reflectance electronic spectra and ESR. The solid reflectance electronic spectra and IR indicate the presence of interaction between the heteropolyanion and the organic substrates in the solid state. Photosensitivity to ultraviolet light was assessed for the complexes, resulting in charge-transfer by oxidation of the organic substrates and the reduction of the heteropolyanion.Four novel polyoxometalate compounds containing transition metals: [(PW₁₂O₄₀){Zn(C₁₀H₈N₂)₂(H₂O)}]·1.5[Zn(C₁₀H₈N₂)₃]·2(OH^-)·H₂O(1), [Zn(C₁₀H₈N₂)₃][PMo₁₂O₄₀(VO)₂] (2) , H₁₁[PMo₁₂O₄₀(VO)₄][V₂O₇]₂·3H₂O (3) and H₇[AsMo₈V₆O₄₂]·en·4H₂O (4) were synthesized and characterized by X-ray crystallography and IR. The results of IR and X-ray analysis show that there exists strong interaction between the polyoxometalate and organic donors in compound (1) and compound (2). The heteropolyanion of compound (3) exhibits a tetracapped α-Keggin-type structure, while the heteropolyanion of compound (4) has a novel bicapped pseudo-Keggin structure.The oxidation of 2-octanol to hexanoic acid using (NH₄)₇[Mo₈V₅O₄₀]·10H₂O and (NH₄)₁₅[Ce(Mo₉V₂O₃₉)₂]·5H₂O as the catalyst were studied. The results showed that (NH₄)₇[Mo₈V₅O₄₀]·10H₂O and (NH₄)₁₅[CeCMo₉V₂O₃₉₂]·5H₂O can improve the yield of hexanoic acid, and (NH₄)₇[Mo₈V₅O₄₀]·10H₂O is superior to (NH₄)₁₅[Ce(Mo₉V₂O₃₉)₂]·5H₂O. The optimum reaction conditions were obtained with (NH₄)₇[Mo₈V₅O₄₀]·10H₂O as catalyst.