Alkaline earth/rare earth halides and related systems

Abstract

Halides of di- and trivalent metals of the general formula BX 2 and MX 3 may react with each other forming a fair variety of complex halides in the solid state. Examples for ternary chlorides are: Ba 2ErCl 7 with isolated [ErCl 7] monocapped trigonal prisms, Ba 2Cl[ScCl 6] with isolated octahedra [ScCl 6] and solitary Cl −, Ba 8[{Sm 6Z}Cl 32] and Ba 9[{Sm 6Z}Cl 34] with Z being presumably an oxide ion residing in the large hole of the [Sm 6Cl 36] polyhedral clusters that occur in these fluorite type superstructures, and, finally, BaGdCl 5 with corrugated layers of edge- and vertex-connected [GdCl 8] square antiprisms. Two further lines may be followed: Firstly, with Nd 8[{Nd 6Z}Cl 32] and Nd 9[{Nd 6Z}Cl 34] isostructural with the above-mentioned chlorides with polyhedral clusters, other intra-rare-earth mixed valence halides may be investigated. “Sm 14Cl 33” is one example. Secondly, with the ionic radius of In 3+ in between those of Lu 3+ and Sc 3+, the BaCl 2/InCl 3 system comes into view. With ZnCl 2 as the solvent, Ba 6ZnIn 2Cl 20 and BaZnCl 4 (GaCl 2 type of structure) were obtained. Following this line further, SrZnCl 4 (scheelite type) was obtained as a model for EuZnCl 4, and, instead of BaCoCl 4, Ba 2CoCl 6 with edge-sharing bioctahedra according to Ba 2Cl 2[Co 2Cl 10].