Synthesis, hydrogen-bonded 1D structure, and abrupt spin transition between high-spin (HS) and an ordered [HS–HS–HS–LS] of a mononuclear iron(III) complex [FeIII(Him)2(4-MeOhapen)]CF3SO3 (Him = imidazole, 4-MeOhapen = N,N′-bis(2-oxy-4-methoxyacetophenylid

• Spin crossover iron(III) complex [FeIII(Him)2(4-MeOhapen)]CF3SO3 was synthesized.
• FeIII ion has an octahedral coordination geometry by a N2O2 Schiff-base ligand and two imidazoles.
• The complex has a hydrogen-bonded one-dimensional chain structure via CF3SO3−.
• Hysteretic and symmetry breaking spin transition between HS and [HS–HS–HS–LS] is observed.

A SCO iron(III) complex [FeIII(Him)2(4MeOhapen)]CF3SO3 was synthesized, where Him = imidazole and 4-MeOhapen = N,N′-bis(2-oxy-4-methoxyacetophenylidene)ethylenediamine. FeIII ion has an octahedral coordination geometry with N2O2 donor atoms of the equatorial tetradentate ligand (4-MeOhapen) and two nitrogen atoms of two imidazoles (Him) at the axial positions. The adjacent cations are bridged by CF3SO3− ion through NH⋯O hydrogen bonds between Him and CF3SO3− to give a one-dimensional chain structure {[FeIII(Him)2(4MeO-hapen)]CF3SO3}1∞. The magnetic susceptibility measurements showed that complex exhibits an abrupt spin transition between a single HS phase and a symmetry-breaking [HS–HS–HS–LS] phase and another transition around 80 K. The single-crystal X-ray analyses at 296 and 150 K revealed the structures at a single HS and [HS–HS–HS–LS] states.

A SCO iron(III) complex [FeIII(Him)2(4MeOhapen)]CF3SO3 was synthesized, where Him = imidazole and 4-MeOhapen = N,N′-bis(2-oxy-4-methoxyacetophenylidene)ethylenediamine. Adjacent cations are bridged by a CF3SO3− ion through NH⋯O hydrogen-bond between Him and CF3SO3− to give a one-dimensional chain structure {[FeIII(Him)2(4MeO-hapen)]CF3SO3}1∞. The magnetic susceptibility measurements and the single-crystal X-ray analyses revealed a symmetry-breaking spin transition between HS and an ordered [HS–HS–HS–LS] phases.Figure optionsDownload as PowerPoint slide