Structural phase transition and magnetic properties of layered organic–inorganic hybrid compounds: p-Haloanilinium tetrachlorocuparate(II)

Compounds of the general formula A2CuCl4, (where A = 4-fluoroanilinium (1) and 4-chloroanilinium (2)) were prepared, structurally characterized and their thermal and magnetic properties studied. These compounds have a layered structure, distorted perovskite, where layers of CuCl42− are sandwiched between a 4-haloanilinium cation bilayer. A single crystal X-ray diffraction study on (4-fluoroanilinium)2CuCl4, (1), shows that it crystallizes in the monoclinic P21/c space group with cell dimensions a = 15.5113(5) Å, b = 7.3788(2) Å, c = 7.0929(2) Å, β = 99.004(2)°, volume 801.81(4) Å3 at 150 K. Compound 2, (4-chloroanilinium)2CuCl4, crystallizes isostructurally to 1 at RT, but at 150 K it adopts the Pccn space group. This structural transition for 2 is reversible, and has been observed using Differential Scanning Calorimetric (DSC) measurements. The dc-magnetic studies using a SQUID magnetometer suggest that both compounds are soft ferromagnets and show an onset of long range magnetic ordering below 9 K. The ac-susceptibility measurements confirm the presence of this ferromagnetic ordering in both the compounds.

The synthesis and detailed investigation of new layered organic–inorganic hybrid compounds, (4-fluoroanilinium)2CuCl4 and (4-choloroanilinium)2CuCl4, are discussed. A DSC study on the latter compound shows a reversible structural phase transition at around 3 °C, which is confirmed by the single crystal X-ray diffraction measurements. These compounds show ferromagnetic ordering below 9 K.Figure optionsDownload as PowerPoint slideHighlights
► Synthesis of layered organic–inorganic hybrid compounds, (4-fluoroanilinium)2CuCl4.
► Layers of CuCl42− octahedra are sandwiched between 4-haloanilinium cation bilayer.
► DSC and single crystal X-ray study showed reversible structural phase transition.
► These compounds show ferromagnetic ordering below 9 K.