Isomerism of heteropolyanions

Papers on geometric isomers of molybdenum, tungsten, vanadium heteropolyanions of Keggin-Dowson structures are reviewed. Structure aspects are considered. Main attention is paid to preparation and properties of heteropolyanion isomers in solutions, to their stability and reciprocal transitions. Electron absorption spectra of isomers and effect of protonation and other factors on them are considered. Data on application of heteropolyanion isomerization in analytical chemistry are presented