A less common spin-crossover process observed in the six-coordinated model heme complexes

Abstract The physicochemical properties of a series of the six-coordinated iron(III) diazaporphyrinate complexes, [Fe(DAzP)L 2 ] ± where the axial ligands (L) are DMAP, CN − , HIm, Py, 3-ClPy, 4-CNPy, 3-CNPy, 3,5-Cl 2 Py, THF, have been examined by combined analyses of NMR, EPR, Mossbauer spectrometry, and SQUID magnetometry. The solution and solid-state studies clarified that the complexes with 3-ClPy, 4-CNPy, 3-CNPy, 3,5-Cl 2 Py are in the less common spin-crossover process between S =  3/2 and S =  1/2 during the temperature change. The results clearly indicate that the complexes showed the switching behaviors of the electronic structure or the magnetic properties responsive to the external stimuli.