Fig. 5. ⁵⁷Fe Mössbauer spectra of 1, recorded at a temperature of 170 and 80 K after cooling from room temperature at a rate of 2 K min⁻¹ and at a temperature of 80 K after rapid cooling (with liquid nitrogen and storing for 5 h at liquid nitrogen temperature before initiation of the ⁵⁷Fe Mössbauer spectroscopy measurement).