Synthese, Structures, Characterizations Of Polyoxometalate Clusters Decorted By Metal-biimidazole Complexes

In this paper, nine polyoxometalates with supporting- and substituting-type based on Strandberg phosphomolybdates ({P₂Mo₅}) and monovacant Keggin tungstophosphates ({PW₁₁}) have been obtained under hydrothermal conditions and routine synthetic method, the transition metal ions (such as Cu^â…¡,Zn^â…¡,Fe^â…¢,Mn^â…¡, etc.) and 2, 2'-biimidazole (H₂biim,Hbiim- or biim^2-) have been introduced into the skeleton structures of these polyoxoanions. All compounds have been characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, TG analysis and electrochemical analysis. Their electrocatalytic properties toward the reduction of H₂O₂ have been investigated by cyclic voltammetry (CV), the study on the catalytic oxidation of cyclohexanol to cyclohexanone in acetonitrile solvent has been done when using compound 9 as catalyst and H₂O₂ as oxidant.1. Six supporting-type inorganic-organic heteropoly anions with various structures based on {P₂Mo₅} polyanion have been designed and synthesized by introducing Cu-/Zn-H2biim complexes:{Cu(H₂biim)₂(H₂O)}[Cu(H₂biim)₂(HPO₄)₂(Mo₅O₁₅)]·2H₂O (1)[{Cu(H₂biim)(H₂O)}₂{μ-Cu(H₂biim)(H₂O)}(P₂Mo₅O₂₃)]₂·20H₂O (2){Cu(H₂biim)₂}[{Cu(H₂biim)(H₂O)₂}{Cu(H₂biim)₂}(HPO₄)(PO₄)(Mo₅O₁₅)]₂·20H₂O (3){H₆(H₂biim)₃}[Zn(H₂biim)(H₃biim)(H₂O)(PO₄)(PMo₅O₁₉)]₂·3H₂O (4){H₁₂(H₂biim)₇}[μ-(biim){Zn(H₂O)₂(P₂Mo₅O₂₃)}₂]·7H₂O (5){H₁₀(H₂biim)₇}[Zn(H₂biim)(H₂O)₂(P₂Mo₅O₂₃)](P₂Mo₅O₂₃)·9H₂O (6)2. The transition metal atom Fe(^â…¡I), Mn(^â…¡) are as the center of inversion symmetry to assemble two dumbbell-like structures with {P₂Mo₅} polyanion by routine synthetic method:{H₉(H₂biim)₇}[μ-Fe(H₂O)₄(P₂Mo₅O₂₃)₂]·10H₂O (7){H₁₀(H₂biim)₇}[μ-Mn(H₂O)₄(P₂Mo₅O₂₃)₂]·10H₂O (8)3. A polyoxometalate cluster with embedding, outside-hanging and free Cu-H2biim complexes based on {PW₁₁} polyanion has been obtained by self-assembled under hydrothermal conditions based on {PW₁₁} fragment.{Cu(H₂biim)₂(H₂O)}[Cu(H₂biim)₂Cu(H₂biim)(μ-Hbiim)CuPW₁₁O₃₉]·5H₂O (9)...