Competing Symmetry Breaking and Spin Crossover in [FeH2L2–Me](ClO4)2



In this contribution, we describe the symmetry breaking that appears in the low-spin phase of the spin crossover (SC) complex [FeH2L2–Me](ClO4)2, [H2L2–Me = Bis{[(2-methylimidazol-4-yl)methylidene]-3-aminopropyl}ethylenediamine], for which low-spin (LS) to high-spin (HS) transition may be thermally activated or photoinduced. In the LS phase stable at low temperature, a symmetry breaking occurs at around 120 K, while in the photoinduced HS (PIHS) state the high symmetry is recovered. The relaxation from this PIHS state to the LS low-symmetry phase occurs through an intermediate LS high-symmetry phase. The sequence of phases was evidenced by using magnetic susceptibility, X-ray diffraction, and infrared spectroscopy data.