Oxo-selenates

Generally, oxo-selenates can be classified according to the oxidation state of the selenium atom as oxu-selenates(IV), and o.Yo-selenates(VI). The same applies for the respective tellurates. Besides this systematically correct naming, chemists usually use the terms selenites and tellurites instead of o. o-selenates(IV) and oxo-tellurates(IV), and selenates and tellurates instead of OAO-selenates(VI) and oxo-tellurates(VI). Therefore, both nomenclatures will be used in parallel throughout this chapter. Compared to the respective sulfur species, the oxo-selenate(IV) and oxo-tellurates(IV) ions are very stable so that numerous compounds with these anions have been prepared. 

A compound containing both Se6+ and Se4+ species is Na2Se04 H2Se03 H20. It has been investigated by X-ray methods and vibrational spectroscopy.84 More recently, the acidic oxo-selenate(I V) KH3(Se03)2 has been reported.85... 

M.S. Wickleder, Oxo-selenates of rare earth elements, in Handbook on the Physics and Chemistry of Rare Earths, K. Gschneidner Jr., J-.C.G. Biinzli and Y.K. Pecharsky (eds), Vol. 35, Elsevier Science Publishers, New York, 2005, 45-106. 

Mathias S. Wickleder, Oxo-selenates of rare earth elements 45... 

In general, oxu-selenates of the alkali metals have been investigated to a lesser extent than the respective sulfates, but on the other hand, oxo-selenates(IV) are better investigated than their sulfur analogues. As discussed for the add sulfates, also addic selenates are of interest with respect to their hydrogen-bonding systems and the properties assodated with them. Therefore, often neutron diffraction studies have been applied to locate hydrogen atoms. 

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