Sandwich-type Uranium-Substituted of Bismuthotungstate: Synthesis and Structure Determination of [Na(UO2)2(H2O)4(BiW9O33)2]13

The sandwich-type [Na(UO 2 ) 2 (H 2 O) 4 (BiW 9 O 33 ) 2 ] 13− uranium ( VI ) has been synthesized by reacting the trivacant species of B-α-[BiW 9 O 33 ] 9− with and investigated by IR and UV–Vis spectroscopy, and elemental analysis. The X-ray single crystal analysis was carried out on Na 13 [Na(UO 2 ) 2 (H 2 O) 4 (BiW 9 O 33 ) 2 ] · 33H 2 O ( I ) which crystallizes in the orthorhombic system, space group Pna2 1 with a = 33.8454(19) Å, b = 21.1484(12) Å, c = 13.2403(7) Å, α = 90°, β = 90°, γ = 90°, and Z = 4. The polyanion consists of two lacunary B-α-[BiW 9 O 33 ] 9− groups which sandwich two uranyl cations and one sodium cation. The uranium atoms adopt distorted pentagonal–bipyramidal coordination, achieved by two equatorial bonds to each BiW 9 O 33 unit and one external water ligand. The coordination of each uranium atom is evident by the shift of ν as (W–O b –W) and ν as (Bi–O) stretching vibrational bonds.