A new organic-inorganic hybrid polyoxoniobate based on Lindqvist-type anion and nickel complex

A new organic-inorganic hybrid polyoxoniobate (H2en)2[Ni(en)3][H2Nb6O19] center dot 5.5H2O (1) (en = ethylenediamine) has been synthesized by the diffusion method and structurally characterized by elemental analyses, infrared spectrum, ultraviolet (UV) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction, thermogravimetric (TG) analysis, and single-crystal X-ray diffraction. Crystal structure analysis reveals that 1 exhibits a 3-D supramolecular architecture constructed from Lindqvist-type [H2Nb6O19]6- polyoxoanions and [Ni(en)3]2+ via hydrogen-bonding interactions. The XPS measurement indicates that the oxidation state of Ni is +2. TG curve of 1 exhibits two steps of weight loss. In situ UV spectra display that 1 can exist in large pH range in aqueous solution.