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

Abstract

Compounds of the general formula A 2CuCl 4, (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 CuCl 4 2− are sandwiched between a 4-haloanilinium cation bilayer. A single crystal X-ray diffraction study on (4-fluoroanilinium) 2CuCl 4, ( 1), shows that it crystallizes in the monoclinic P2 1/ 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) Å 3 at 150 K. Compound 2, (4-chloroanilinium) 2CuCl 4, 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.