A new tetra-Zr(iv)-substituted polyoxotungstate aggregate

A new tetra-Zr-substituted tungstophosphate (TP), [H₂N(CH₃)₂]₆Na₆H₈{Zr₂[SbP₂W₄(OH)₂O₂₁][α₂-PW₁₀O₃₈]}₂·50H₂O (1), has been made by the hydrothermal reaction of the [B-α-SbW₉O₃₃]^9- building block with Zr⁴⁺ cations and PO₄ ^3- anions in the presence of dimethylamine hydrochloride and NaOAc-HOAc (pH = 4.8), and further characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), ³¹P NMR spectroscopy and single-crystal X-ray diffraction. 1 is a toroidal structure formed by two divacant [α₂-PW₁₀O₃₈]^11- units and two [SbP₂W₄(OH)₂O₂₁]^7- fragments linked by four Zr⁴⁺ cations. Note that the TP is reassembled with tetrahedral PO₄ replacing the triangular pyramidal SbO₃ in the [B-α-SbW₉O₃₃]^9- precursor. In addition, the pendant SbO₃ derives from the dissociation of the [B-α-SbW₉O₃₃]^9- precursor. Furthermore, the electrochemical properties of 1 have been studied in Na₂SO₄ + H₂SO₄ supporting electrolyte (0.5 mol L^-1), and indicate that 1 exhibits apparent catalytic activity toward H₂O₂ and BrO₃ ^- reduction. The ³¹P NMR spectrum of 1 exhibits three signals with approximately proportional intensities, which is consistent with the solid-state structure.