Cobalt, Manganese, Nickel, and Vanadium Derivatives of the Cyclic 48-Tungsto-8-Phosphate [H7P8W48O184]33−

The cobalt(II) containing tungstophosphate [Co4(H2O)16P8W48O184]32− (1) has been synthesized by addition of Co2+ ions to an aqueous solution of [H7P8W48O184]33− (P8W48) and characterized by single-crystal XRD, IR, and UV−vis spectroscopy, elemental analysis, electrochemistry, and magnetochemistry. The novel polyanion 1 is a derivative of the superlacunary P8W48 with four cobalt(II) ions coordinated to the rim of the central cavity and two additional cobalt(II) ions linked on the outside bridging neighboring polyanions. Using similar synthetic procedures, but adding a few drops of H2O2, we isolated the manganese(II) derivative [Mn4(H2O)16(P8W48O184)(WO2(H2O)2)2]28− (2) and its nickel(II) analogue [Ni4(H2O)16(P8W48O184)(WO2(H2O)2)2]28− (3). Both polyanions have picked up two equivalents of tungsten resulting in the unprecedented {P8W50} host framework. We also made the vanadium(V) derivative [(VO2)4(P8W48O184)]36− (4), with four tetrahedral vanadate groups grafted to the P8W48 host. The voltammetric pattern...