Multinuclear Cobalt(II)-Containing Heteropolytungstates: Structure, Magnetism, and Electrochemistry

Interaction of the trilacunary Keggin polyanions [A-α-XW₉O₃₄]^10– (X = Si^IV, Ge^IV) with Co^II and phosphate ions in aqueous, basic media and under mild heating leads to the formation of the tetrameric, Co₁₆-containing heteropolytungstates [{Co₄(OH)₃PO₄}₄(A-α-XW₉O₃₄)₄]^32– (X = Si^IV, Ge^IV). Both polyanions were characterized in the solid state by single-crystal X-ray diffraction, IR spectroscopy, and thermogravimetric and elemental analyses. Furthermore, the electrochemical and magnetic properties of these isostructural polyanions were investigated.