Heteropolyvanadomanganates(IV) with Mn:V = 1:11 and 1:4

Article abstract of DOI:10.1021/ic50091a010

Two new vanadomanganate(IV) heteropoly complexes have been prepared by reaction of manganese(II), peroxydisulfate, and isopolyvanadate(V) ions. One complex, isolated as K₅MnV₁₁O₃₂·10H₂O, Cs_4.5H_0.5MnV₁₁O₃₂·7H ₂O, and (NH₄)_4.5H_0.5MnV₁₁O ₃₂·12H₂O (all red to dark red crystals) is moderately stable in solutions of pH 2-3. In the pH range 4-6 it reacts to give high yields of 13-vanadomanganate(IV), accompanied by some amorphous precipitate and at least one other complex in low yields. The second complex, isolated as K₅HMn₃V₁₂O₃₉·10H₂O and (NH₄)₅HMn₃V₁₂O ₈₉·15H₂O (black crystals), is also obtained in the pH range 2-3 and apparently exists up to a pH near 6. It is formulated as a trimeric species on the basis of the chemical analyses and single-crystal X-ray data. The 3:12 complex is unexpectedly inert to reaction with excess vanadium(V) to give 1:11 or 1:13 complexes. No visual evidence for heteropoly blue species was observed on reduction of the complexes. The 1:13 complex was found to be slightly photosensitive, the decomposition products apparently including the green reduced species. The acid decomposition of vanadomanganates(IV) leads to formation of small quantities of permanganate; similar behavior was noted for 12-niobomanganate(IV).