Abstract: | Jahn‐Teller Ordering in Manganese(III) Fluoride Sulphates. I. Crystal Structures of A2MnF3(SO4)] (A = Rb, NH4, Cs) The three isostructural fluorosulphatomanganates(III) A2MnF3(SO4)] (A = Rb, NH4, Cs) crystallize in space group P21/c, Z = 4. Rb2MnF3(SO4)]: a = 7.271, b = 11.091, c = 8.776Å, β = 92.26°, R = 0.033; (NH4)2MnF3(SO4)]: a = 7.299, b = 10.157, c = 8.813Å, β = 91.51°, R = 0.025; Cs2MnF3(SO4)]: a = 7.365, b = 11.611, c = 9.211, β = 92.30°, R = 0.029. In the chain anions MnF3(SO4)]2— manganese(III) is coordinated by two trans‐terminal and two trans‐bridging fluorine ligands, and by the O‐atoms of two briding sulphate ligands in trans position. The Jahn‐Teller effect induces a variety of antiferrodistortive ordering resulting in distorted MnF4O2] octahedra with alternating elongation of F—Mn—F — and O—Mn—O — axes, respectively. Thus, only asymmetrical bridges are formed. |