Ammonium metavanadate is the inorganic compound with the formula NH4VO3. It is a white salt, although samples are often yellow owing to impurities of V2O5. It is an important intermediate in the purification of vanadium.Günter Bauer, Volker Güther, Hans Hess, Andreas Otto, Oskar Roidl, Heinz Roller, Siegfried Sattelberger "Vanadium and Vanadium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim.
Synthesis and structure The compound is prepared by the addition of ammonium salts to solutions of vanadate ions, generated by dissolution of V2O5 in basic aqueous solutions, such as hot sodium carbonate. The compound precipitates as a colourless solid.G. Brauer "Ammonium Metavanadate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1272.Robert H. Baker, Harry Zimmerman, R. N. Maxson "Ammonium Metavanadate" Inorganic Syntheses, 1950, Vol. 3, 117-118. This precipitation step can be slow.
The compound adopts a polymeric structure consisting of chains of [VO3]−, formed as corner-sharing VO4 tetrahedra. These chains are interconnected via hydrogen bonds with ammonium ions. ball-and-stick modelpolyhedral model[(VO3)n]n− chains
Uses Vanadium is often purified from aqueous extracts of slags and ore by selective precipitation of ammonium metavanadate. The material is then roasted to give vanadium pentoxide: 2 NH4VO3 → V2O5 + 2 NH3 + H2O
Other Vanadates can behave as structural mimics of phosphates, and in this way they exhibit biological activity.Korbecki, Jan; Baranowska-Bosiacka, Irena; Gutowska, Izabela; Chlubek, Dariusz "Biochemical and medical importance of vanadium compounds" Acta Biochimica Polonica 2012, vol. 59, pp. 195-200.Crans, D. C.; Chatterjee, P. B. "Vanadium Biochemistry" Reedijk, Jan; Poeppelmeier, Kenneth, Eds. Comprehensive Inorganic Chemistry II (2013), 3, 323-342.
Ammonium metavanadate is used to prepare Mandelin reagent, a qualitative test for alkaloids.
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