Zur Kenntnis von Alkalimetaselenoarseniten Darstellung und Kristallstrukturen von MAsSe2, M = K,Rb, Cs

Concerning Alkali Metal Metaselenoarsenites. Preparation and Crystal structures of MAsSe₂, M = K, Rb, Cs The metaselenoarsenites MAsSe₂, M = K, Rb, Cs were prepared by methanolothermal reaction of M₂CO₃ with As₂Se₃ at a temperature of 130°C. Their X-ray structural analyses demonstrated that the compounds contain polymetaselenoarsenite anions [AsSe₂^?]_∞, in which the basic units are ψ-AsSe₃ tetrahedra, which are linked via shared corners into infinite chains. Vierer single chains are observed for KAsSe₂ and RbAsSe₂, zweier single chains for CsAsSe₂. The stretching units s are respectively 3,157, 2.336 and 3,378 Å. The relationship between the conformation of metaselenoarsenite chains and cation size is discussed.