Syntheses, Structural Characterization, and Catalytic Properties of Di- and Trinickel Polyoxometalates.

The sandwich-type polyoxometalate Na8Li12 [Ni2(P2W15O56)2] ·74H2O (I) is obtained by slow evaporation of a solution containing NiCl2 and Na3PO4 in 4 M LiCl at pH 8 to which Na12[α-P2W15O56] is added (60 °C, 1 h, 40% yield).