An unprecedented Zr-containing polyoxometalate tetramer with mixed trilacunary/dilacunary Keggin-type polyoxotungstate units

A novel zirconium(IV)-substituted tetramer polyoxotungstate, H₆K₄Na₁₆[Zr₄(β-GeW₁₀O₃₈)₂(A-α-PW₉O₃₄)₂]·37H₂O, was synthesized hydrothermally and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, energy-dispersive X-ray spectroscopy and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic P2/n space group. The most remarkable feature is that the centrosymmetric Zr-based polyoxotungstate tetramer consists of dilacunary Keggin-type germanotungstate and trilacunary Keggin-type phosphotungstate units that are linked by Zr^IV ions.