Multinuclear cobalt(II)-containing heteropolytungstates: structure, magnetism, and electrochemistry.

Interaction of the trilacunary Keggin polyanions [A-α-XW9O34]10– (X = SiIV, GeIV) with CoII 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 = SiIV, GeIV). 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.