| Abstract: | During the mixing of ethylenediammonium dichloride and antimony trichloride except of reported earlier NH3(CH2)2NH3]5(Sb2Cl11)2 · 4 H2O a new salt NH3(CH2)2NH3](SbCl4)2 was obtained. The crystals are monoclinic at 295 K, space group C2/m, a = 13.829(3), b = 7.408(1), c = 7.588(2) Å; β = 103.18(3)°; V = 756.9(3) Å3; Z = 2; dc = 2.585, dm = 2.56(2) g · cm–3. The structure consists of anionic sublattice built of Sb2Cl82– units composed of two SbCl52– square pyramids connected by edge. The ethylenediammonium cations are located in anionic cavities. The cations are disordered. Each methylene carbon atom is split between two positions. The X‐ray diffraction, DSC, TGA and dilatometric methods were used to investigate properties of ethylenediammonium dichloride and its two salts with antimony trichloride. In NH3(CH2)2NH3]Cl2 one phase transition of first order and of the order‐disorder type was found at 402 K. The NH3(CH2)2NH3]5(Sb2Cl11)2 · 4 H2O undergoes one transition at 355 K which is accompanied by the dehydration of the sample. In NH3(CH2)2NH3](SbCl4)2 two phase transitions of the order‐disorder type: of first order at 238 K and of second order at 267 K were found. All those transitions in ethylenediammonium salts share common features. They were related to the changes in the molecular dynamics of ethylenediammonium cations. In the low temperature phases cations are ordered, while above Tc they are characterised by overall reorientations along the axis passing through opposite nitrogen atoms. |
