Hydrothermal syntheses and structural characterization of two organic–inorganic hybrid compounds based on Lindqvist polyanions

Abstract

Two organic–inorganic hybrid polyoxometalates {[V2W4O19{Cu(2,2′-bipy)2}2] · (4,4′-bipy)} n (1) and [Co(2,2′-bipy)3][W6O19] · H2O (2) (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine), constructed by Lindqvist polyanions and transition metal coordination cations, have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, UV spectra, thermogravimetric (TG) analyses, X-ray photoelectron spectroscopy (XPS), and single- crystal X-ray diffraction. Compound 1 is a neutral molecule and consists of a di-VV substituted Lindqvist-type polyanion [V2W4O19]4−, two supporting copper cations [Cu(2,2′-bipy)2]2+ and one free 4,4′-bipy. Neutral molecules of 1 are extended to a 2-D grid-like network by π–π stacking interactions between pyridine groups. The molecular structure of 2 contains one [W6O19]2− cluster polyanion and a [Co(2,2′-bipy)3]2+. Inductively coupled plasma (ICP) analysis and XPS spectrum of 1 prove the presence of VV. TG curves of 1 and 2 indicate two weight loss steps.