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)]center dot H2O have been prepared and studied by magnetic susceptibility, DSC and Mossbauer measurements. The three compounds exhibit an abrupt spin transition associated with thermal hysteresis, a still rarely observed behavior for ferric complexes. DSC and Mossbauer 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. (C) 2014 Elsevier Ltd. All rights reserved.