A Symmetry‐Breaking Spin‐State Transition in Iron(III)

Abstract

Stepping up: A two-step magnetic spin transition with accompanying structural phase transitions is reported for the first time for FeIII. The transitions are observed at 187 K and 90 K on cooling with a hysteretic transition recorded upon heating during the first crossover at 106 K. The intermediate phase persists over 97 K and contains an unprecedented [HS-HS-LS] motif with tripling of the unit cell.