Synthesis and characterization of Cs5In3As4 with a structure of two coexisting "polymorphic" forms of different dimensionality

The title compound was made by fusion of a stoichiometric mixture of the pu re elements at 500 degreesC. The structure (monoclinic, P2(1)/c, Z = 8, a = 17.037(6), b = 12.253(1), c = 18.105(4) Angstrom, beta = 117.24(2)degrees) is made of alternating one- and two-dimensional sections with the same com position of Cs5In3As4, and can be considered as two coexisting polymorphic forms of the same compound. The chains and layers in these sections are mad e of repeating semicubane motifs of [In3As4](5-) that are connected to each other by In-As bonds in the chains, and by both In-As and In-In bonds in t he layers. According to magnetic measurement and EHMO calculations, Cs5In3A s4 is a closed-shell compound that fulfills the Zintl concept.