Investigation of ammonium substitution in the perovskite-like structure Rb0.79(NH4)0.21CdCl3

A novel rubidium–ammonium cadmium trichloride has been prepared and characterized by X-ray single crystal analysis at room temperature. Rb0.79(NH4)0.21CdCl3 crystallizes in the orthorhombic space group Pnma with Z = 4 and unit cell dimensions a = 8.9654(2) Å, b = 4.0200(1) Å, c = 14.9489(6) Å. Several cycles of least-squares refinement reduced the disagreement R(F) factor for 733 reflections to a final value of 0.0207. The compound structure consists of Rb+ (or NH 4 + ) ions and double chains of CdCl6 octahedra sharing one edge extending along “b” axis. The mixture of Rb+/ NH 4 + cations are located between the double chains ensuring the stability of the structure by ionic and hydrogen bonding contacts N–H ⋯ Cl. By comparison with RbCdCl3 the ammonium-substituting does not affect the structural arrangement, but it leads to decrease of the “b” and “c” orthorhombic lattice cell dimensions and the Cd–Cl distances and gives more disorder of NH 4 + groups.