Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The acid-base reaction between Na₂MoO₄ + Na₄As₂O₇ as Lux bases dissolved in an NaNO₃ + KNO₃ melt and an NO₂ + O₂ gas mixture as a Lux acid gave a novel heteropolyacid salt whose composition is approximately (Na, K)₁₈As₂Mo₁₇O₆₅, (Na, K)₁₆As₂Mo₁₈O₅₆, (Na, K)₁₆As₂Mo₁₇O₆₄. This compound can also be obtained by direct fusion of the components (Na₄As₂O₇, Na₂MoO₄ and MoO₃) over the temperature region of 420-600 °C. Based on the study of the arsenate and diarsenate ions in a nitrate melt and the molecular spectra of the compound obtained it is suggested that the basic unit of the heteropolyanion structure is the diarsenate anion. The formation of analogous compounds can generally be expected for X/Z combinations with X = P(V), As(V), V(V) and Z = Mo(VI), W(VI).