CsVP₂S₇

The quaternary vanadium thio­phosphate CsVP₂S₇ (caesium vanadium diphospho­rus heptasulfide) was synthesized by reacting a mixture of Cs₂S₃, V, P₄S₃ and S. The crystal structure is composed of VS₆ octahedra, which are linked by bitetrahedral [P₂S₇] groups to form two-dimensional anionic [VP₂S₇]^- layers. The layers are stacked perpendicular to the crystallographic c axis and are separated by the Cs⁺ ions. The VS₆ octahedra, the [P₂S₇] groups and the Cs⁺ ions are located in special positions. CsVP₂S₇ is isostructural to KVP₂S₇ and RbVP₂S₇.

K₄Ta₄P₄S₂₄

The quaternary tantalum thio­phosphate K₄Ta₄P₄S₂₄ (tetrapotassium tetratantalum tetraphospho­rus tetracosasulfide) was obtained by reacting elemental Ta with a melt formed in situ of K₂S₃, P₂S₅ and S. The crystal structure exhibits [Ta₄P₄S₂₄]^4- anionic layers, which consist of dimeric Ta₂S₁₁ units interconnected by PS₄ tetrahedra. The layers are stacked in an ABAB sequence in the direction of the crystallographic a axis and are separated by the K⁺ ions. The title compound is isostructural with A₄Ta₄P₄S₂₄ (A = Rb and Cs).