Synthesis and Characterization of 0D-3D Copper-Containing Tungstobismuthates Obtained from the Lacunary Precursor Na9[B-α-BiW9O33].

The reaction of the lacunary polyoxometalate precursor Na9[B-α-BiW9O33]·19.5H2O with Cu(II) ions was explored in search of new economic ways to copper tungstobismuthates as interesting prototypes for water oxidation and reduction catalysts. The emerging series of new 0D-3D polyoxometalate architectures with distinct copper cores was structurally characterized. Na6Rb6[Cu3(H2O)3(BiW9O33)2] (Cu-4) and 3D-K6.56Cu0.43H2.20[(Cu3Cl)(K2.62Cu0.38(H2O)3)(B-α-BiW9O33)2]·13H2O (Cu-5) display a Cu3(H2O)3 core. The 2D representatives Na12[Cu2(H2O)4Cl2(BiW10O35)2] (Cu-1a), Na10[Cu2(H2O)6(BiW10O35)2] (Cu-1b), 2D-Na7K3Cu0.5Cl[Cu2(H2O)4(BiW10O35)2] (Cu-2), and 2D-Na5.5K2.5Cu[Cu2(H2O)4(BiW10O35)2] (Cu-3) contain Cu2(H2O)nW2O4 cores. Interestingly, the bismuth-free 1D paratungstate B Na4K4Cu[H2W12O42] (Cu-6) is formed through reassembly of the precursor. Cu-5 displays a disordered transition metal core, implying the presence of the polyanions [Cu4(H2O)4(BiW9O33)2]10- and [Cu5(H2O)5(BiW9O33)2]8-. The magnetic properties of Cu-5 as well as its activity as visible-light-driven H2 and O2 evolution catalyst were evaluated.