Antimony tetroxide explained

Antimony tetroxide is an inorganic compound with the formula Sb₂O₄. This material, which exists as the mineral cervantite,^[1] is white but reversibly yellows upon heating. The material, with empirical formula SbO₂, is called antimony tetroxide to signify the presence of two kinds of Sb centers.

Formation and structure

The material forms when Sb₂O₃ is heated in air:^[2]

Sb₂O₃ + 0.5 O₂ → Sb₂O₄ ΔH = −187 kJ/molAt 800 °C, antimony(V) oxide loses oxygen to give the same material:

Sb₂O₅ → Sb₂O₄ + 0.5 O₂ ΔH = −64 kJ/mol

The material is mixed valence, containing both Sb(V) and Sb(III) centers. Two polymorphs are known, one orthorhombic (shown in the infobox) and one monoclinic.^[3] Both forms feature octahedral Sb(V) centers arranged in sheets with distorted Sb(III) centers bound to four oxides.

References

1. Web site: Cervantite. 2009-06-06. Webminerals.
2. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. .
3. Amador . J. . Puebla . E. Gutierrez . Monge . M. A. . Rasines . I. . Valero . C. Ruiz . 1988 . Diantimony Tetraoxides Revisited . Inorganic Chemistry . 27 . 8 . 1367–1370 . 10.1021/ic00281a011 .