Heteropolyanions containing two different heteroatoms—I

The following heteropolyanions of general formula XZW11O40H2n− have been prepared: X, Z = Si, Co(III); Ge, Co(II); Ge, Co(III); Si, Ni(II); Ge, Ni(II); P, Ni(II); as well as the unstable anion SiCoMo11O40H26−. Arguments are presented for the presence of Co and Ni in the anions and for the above formulation. The Co(III) species are the most resistant to acid and base attack and solutions of the free acids have been obtained. The ligand-field spectra are discussed.