The two-dimensional thiophosphate CsCrP2S7

Abstract

The quaternary title compound, caesium chromium(III) heptathiodiphosphate(V), CsCrP2S7, has been synthesized using the reactive halide flux method. It is isotypic with other AMP2S7 (A = alkali metal; M = Cr, V or In) structures and consists of two-dimensional ∞2[CrP2S7]− layers extending parallel to (001) which are separated from each other by Cs+ ions (symmetry 2). The layer is built up from slightly distorted octahedral [CrS6] units (symmetry 2) and bent [P2S7] units consisting of two corner-sharing [PS4] tetrahedra. The [CrS6] octahedra share two edges and two corners with the [PS4] tetrahedra. There are only van der Waals interactions present between the layers. The Cs+ ions are located in this van der Waals gap and stabilize the structure through weak ionic interactions. The classical charge balance of the title compound can be expressed as [Cs+][Cr3+][P5+]2[S2−]7.