Formation of Tetraselenodiarsenate(II) Anions in Ultra-alkaline Medium
Albrecht R, Jach F, Ruck M (2021)
Publication Type: Journal article
Publication year: 2021
Journal
DOI: 10.1002/zaac.202100306
Abstract
SeO2 and As2O3 were reacted at 200 °C in in a potassium hydroxide hydroflux with a molar water-base ratio n(H2O) : n(KOH)=1.8. Arsenate(III) disproportionates under these conditions into arsenate(V) and elemental arsenic. The reduction also yielded tetraselenodiarsenate(II) anions, which turned the solution yellow and precipitated at room temperature as plate-shaped crystals of K4(As2Se4) ⋅ 2H2O. The unexpected redox reaction as well as the formation of a hygroscopic compound in an aqueous solution are attributed to a strongly reduced activity of water in ultra-alkaline media. K4(As2Se4) ⋅ 2H2O crystallizes in the orthorhombic space group Cmce with lattice parameters a=784.78(3), b=1027.76(4) and c=1750.63(7) pm at 100 K. The (As2Se4)4− anion has C2h symmetry and an As−As bond length of 245.3(1) pm. The water molecules are part of infinite zig-zag chains (Formula presented.) [K(H2O)2/2]+ and form hydrogen bonds to neighboring selenium atoms.
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How to cite
APA:
Albrecht, R., Jach, F., & Ruck, M. (2021). Formation of Tetraselenodiarsenate(II) Anions in Ultra-alkaline Medium. Zeitschrift für Anorganische und Allgemeine Chemie. https://doi.org/10.1002/zaac.202100306
MLA:
Albrecht, Ralf, Franziska Jach, and Michael Ruck. "Formation of Tetraselenodiarsenate(II) Anions in Ultra-alkaline Medium." Zeitschrift für Anorganische und Allgemeine Chemie (2021).
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Germany (DE)