The InSnCl3-Type Arrangement: I. A New ABX3 Structure Type with Close Cation–Cation Contacts

We report on the synthesis and structure of InSnCl3 and InSnBr3. Their structure represents a new ABX3 structure type which will only be found for compounds with large cations A and B having an ns2 electron configuration. The cations have high coordination numbers and therefore their coordination polyhedra are connected mainly by common edges and even faces. This leads to fairly short cation–cation distances. However, the electrostatic repulsion may be decreased by a shielding effect of the s-electrons. The distribution of the cations on different sites, which cannot be determined by routine X-ray investigations, is discussed on the basis of crystal chemical considerations. Low temperature diffraction measurements on InSnCl3 show that the high symmetry of the arrangement is mimicked by a polydomain configuration, which can be dealt with by a split atom refinement.