Hydrothermal synthesis and characterization of the tri-capped and mono-supported pseudo-Keggin-type tungstovanadophosphate:: {PW4VIW5VV3IVO40(VIVO)3[Cu(en)2]}6-

A novel polyoxometalate [Cu(phen)2]3{(PW4W5V3O40)-W-VI-V-V-O-IV((VO)-O-IV)(3)[Cu(en)(2)]}center dot 4H(2)O 1 (en = ethylenediamine, phen = 1,10-phenanthroline) has been synthesized hydrothermally and characterized by elemental analysis, IR, XPS, TG, EPR and single-crystal X-ray diffraction analysis. The crystal structure analysis shows that compound 1 contains a novel highly reduced tri-capped and monosupported pseudo-Keggin-type heteropolyanion, {(PW4W5V3O40)-W-VI-V-V-O-IV((VO)-O-IV)(3)[Cu(en)(2)]}(6-), three [Cu(phen)(2)](2+) cations and four lattice water molecules. They are further linked to form three-dimensional supramolecular networks through extensive hydrogen bonding and pi-pi stacking interactions. Interestingly, the water dimer and terminal oxygen of the cluster polyanion constitute a beautiful supramolecular helix chain. The heteropolyanion is the first example of tri-capped and mono-supported pseudo-Keggin-type tungstovanadophosphate and the pH value is crucial for obtaining compound I in synthetic procedure. (C) 2007 Published by Elsevier Inc.