Isopoly Compounds

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Isopoly Compounds

 

complex compounds; acids or salts containing a complex anion (polyanion) formed by acid oxides in which the oxygen is partly replaced by the same kind of acid oxide.

Examples of isopoly compounds include pyrosulfuric acid (H2S2O7) and potassium dichromate (K2Cr2 O7), the coordination formulas of which are, respectively, H2[SO3(SO4)] and K2[CrO3(CrO4)]. Isopoly compounds are known mostly for anions containing sulfur, tantalum, niobium, chromium, molybdenum, tungsten, and uranium. X-ray diffraction has shown that the polyanions of isopoly compounds can be represented by short chains of tetrahedra or octahedra, with common edges or ver-texes. Isopoly compounds are prepared either by melting normal salts with acid oxides (for example, Na2WO4 + WO3 = Na2W2O7) or by acidifying aqueous solutions of neutral salts (2K2CrO4 + H2SO4 = K2Cr2O7 + K2SO4 + H2O). Isopoly compounds are used in analytical chemistry.

REFERENCES

Grinberg, A.A. Vvedenie v khimiiu kompleksnykh soedinenii, 3rd ed. Moscow-Leningrad, 1966.
Cotton, F., and G. Wilkinson. Sovremennaia neorganicheskaia khimiia, part 3. Moscow, 1969. (Translated from English.)
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.