X-ray structure of dodecasodium tricopper(II)bis[nonatungstabismuthate(III) hydrate, a polyoxometalate salt containing α-B-BiW9O33 units

The reaction of [Bi₂W₂₂O₇₄(OH)₂]^12– with Cu²⁺ in hot aqueous solution in the presence of Na⁺ affords the polyoxometalate salt Na₁₂[Cu₃Bi₂W₁₈O₆₆]32H₂O. Single-crystal X-ray analysis [monoclinic, space-group C2/m, a = 33.082(6) Å, b = 19.615(5) Å, c = 14.885(2) Å, = 90.632(12)°, Z = 4; R(F) = 0.065 for 6029 data with I> (I), wR(F ²) = 0.135 for all 8793 independent reflections] shows that the anion [{Cu(H₂O)}₃{BiW₉O₃₃}₂]^12–, on a crystal mirror-plane, has noncrystallographic symmetry close to D_3h. Two B--[Bi^IIIW₉O₃₃]^9– units are linked by an equatorial belt of three Cu(H₂O)²⁺ units. Three Na(H₂O)₂ ⁺ units are also attached in the equatorial plane. The bond geometry is square-pyramidal about each Cu atom and trigonal–prismatic about each Na.