Three new extended Preyssler-type polyoxometalates modified by transition metal-2,2′-biimidazole complexes

Three extended Preyssler-type ({P5W30}) polyoxometalates modified by transition metal (TM)-2,2′-biimidazole (abbreviated as H2biim) complexes, namely [Mn(H2biim)3]5H2[{Mn(H2biim)2(H2O)} (NaP5W30O110)]·39H2O (1), [{(H2biim)2Zn(μ-OH)Zn(H2biim)(μ-H2biim)Zn(H2biim)(H2O)}2H4(NaP5W30O110)]·22H2O (2), and {(H4biim)18NaH5[(μ-Fe(H3biim)(H2O)3)(μ-Fe(H2O)4)(NaP5W30O110)2]2·78H2O}n (3) have been hydrothermally synthesized, and characterized by physicochemical and spectroscopic methods. Their catalytic activities have been investigated. 1 contains mono-supporting {P5W30} anions. In compound 2, a {P5W30} anion is bi-supported by two symmetrical chains constructed by trinuclear zinc complexes. Compound 3 is composed of infinite 1-D zigzag chains built up of {P5W30} polyoxoanions linked via [Fe(H2O)4]3+ and [Fe(H3biim)(H2O)3]4+ fragments. H2biim ligands adopt three coordination modes in the structure. All these compounds have 3-D supramolecular frameworks via extensive hydrogen-bonding interactions.

Graphical abstractThree new extended Preyssler-type polyoxometalates modified by TM-2,2′-biimidazole complexes are obtained, they display high thermal stabilities.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Three new extended Preyssler-type polyoxometalates were hydrothermally synthesized. ► An interesting trinuclear zinc-2,2′-biimidazole-polyanion complex was obtained. ► The huge {P5W30} clusters were modified by TM-2,2′-biimidazole complexes. ► There exist different coordinate modes in three compounds for the biimidazole ligand.