Study on A4BX6 compounds. I. Structure Refinement of Ternary Cd Halides A4CdX6 (A = NH4, K, Rb, In, Tl; X = Cl, I)

Abstract The refinement of the structures of rhombohedral (NH 4 ) 4 CdCl 6 , K 4 CdCl 6 , and Rb 4 CdCl 6 (K 4 CdCl 6 ‐type) and of tetragonal In 4 CdI 6 and Tl 4 CdI 6 (Tl 4 HgBr 6 ‐type) using single crystal data is reported. The discussion of the crystal chemistry of these compounds furnishes new structural relations and a first hint of the role, which ns 2 cations play in these structures. All compounds of the A 4 BX 6 family can clearly be separated with respect to their structure in a structure field diagram in the basis of the size relations A/X and B/X.