Spin Properties of a New Iron Complex with Schiff Base

An iron(III) complex with bis-3,4,5-tri(tetradecyloxy)benzoyloxy-4-salicylidene-${\rm{N'}}$-ethyl-N-ethylenediamine with outer-sphere anion NO$^{-}_{3}$ has been investigated by M\"оssbauer spectroscopy, differential scanning calorimetry (DSC), and polarized light microscopy. It has been found that at a temperature of 300 K the iron(III) ions are in a high-spin (S = 5/2) state and are likely to form a dimeric structure. During the heating and cooling cycles, the complex undergoes a glass–solid phase transition at 41.14 $^{\circ}{\rm{C}}$, a solid–solid transition at 49.52 $^{\circ}{\rm{C}}$, and a solid–liquid transition at 144 $^{\circ}{\rm{C}}$. A decrease in temperature leads to a spin-crossover transition, and at 80 K the spectrum area of the low-spin component is about $\approx$ 3.5%. A further decrease in temperature leads to magnetic spin correlations and antiferromagnetic ordering in the system of high-spin Fe(III) centers.