Neutral ferric complexes of salicylaldehyde thiosemicarbazone ligands: An exceptional family of complexes exhibiting discontinuous spin transition behavior

Three neutral thiosemicarbazone ferric complexes of general formulas [Fe(H5XThsa)(5XThsa)]·H2O have been prepared and studied by magnetic susceptibility, DSC and Mössbauer measurements. The three compounds exhibit an abrupt spin transition associated with thermal hysteresis, a still rarely observed behavior for ferric complexes. DSC and Mössbauer measurements allowed confirming that these spin transition processes are coupled with a first order crystallographic phase transition whose thermodynamical parameters have been determined. Finally, it can be highlighted from the comparison of properties observed for these compounds with the literature that the synthetic procedures are a crucial point for the magnetic properties.

Graphical abstractThree neutral thiosemicarbazone ferric complexes [Fe(H5XThsa)(5XThsa)]·H2O (X = H, Cl, Br) are studied by magnetic susceptibility , DSC and Mössbauer measurements. The three compounds display abrupt spin transition with thermal hysteresis, which highlights the fascinating magnetic behavior of this class of ferric complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide