Chalcogenides by Reduction of their Dioxides in Ultra‐Alkaline Media
Ralf Albrecht, Michael Ruck
Abstract
Abstract The reaction of chalcogen dioxides Ch O 2 ( Ch =Se, Te) with As 2 O 3 in a 30 molar KOH hydroflux at about 200 °C yielded crystals of potassium trichalcogenides K 2 Ch 3 with dimensions up to 2 cm. Arsenic trioxide acts as electron donor and is oxidized to arsenate(V). The new heterochalcogenide anion (TeSe 2 ) 2− formed when starting from SeO 2 and TeO 2 simultaneously. The compound K 2 TeSe 2 crystallizes isostructural to K 2 S 3 and K 2 Se 3 . The unexpected redox reaction as well as the precipitation of hygroscopic compounds from an aqueous solution are attributed to a strongly reduced activity of water. The reactions were studied by Raman and UV/Vis spectroscopy. Depending on the concentration of As 2 O 3 , colorless monochalcogenide Ch 2− or orange Se 2 2− and purple Te 2 2− anions are dominating the solutions.