Tuning spin transitions of iron(II)-dpp systems

Chemical modifications of the yet reported iron(II) compound [Fe(dpp) 2 (NCS) 2 ]⋅Py (dpp = dipyrido[3,2a:2’3’c]phenazine, Py = pyridine) which shows abrupt spin crossover below room temperature with large hysteresis have been made. The purpose was to stabilize different spin states at room temperature as well as to adjust the spin crossover in temperature and hysteresis width. We modified the bidentate ligand dpp by substituting hydrogens at the phenazine by different functional groups. In addition, we substituted the thiocyanate monodentate ligands by NCSe − . The spin states of these compounds have been investigated by Mössbauer spectroscopy at two temperatures and temperature depending IR spectroscopy. These methods indicating that the chemical modifications are influencing the observed spin configuration of the complexes alongside the spin crossover behavior which changed to gradual and incomplete transitions. These promising results offer interesting possibilities for chemical adjustments of the shown spin crossover systems.