Divalent titanium:: The halides ATiX3 (A = K, Rb, Cs;: X = Cl, Br, I)

Within the 30 library of ternary alkali halides of titanium(II), ATiX(3) (A = K, Rb, Cs; X = Cl, Br, I), five compounds were synthesized by conproportionation reactions. Single crystals were grown and the structures determined by single-crystal X-ray techniques. The halides ATiX(3) crystallize either with the so-called hexagonal perovskite type structure (CsNiCl3, 2H), or with the so-called KNiCl3-type of structure. This latter type allows two structural degrees of freedom. First, a shift of the colums of face-sharing [TiCl6] octahedra against each other and, secondly, a rotation of these colums relative to each other. With these degrees of freedom, individual coordination spheres are designed for the alkali-metal cations A(+).