Description:
<jats:title>Abstract</jats:title><jats:p>Three new dinuclear complexes [Fe<jats:sup>II</jats:sup><jats:sub>2</jats:sub>(μ‐<jats:bold>L</jats:bold>)<jats:sub>2</jats:sub>]X<jats:sub>4</jats:sub> (<jats:bold>L</jats:bold> is the bis‐tridentate ligand 2,5‐bis{[(2‐pyridylmethyl)amino]methyl}‐1,3,4‐oxadiazole and X = ClO<jats:sub>4</jats:sub><jats:sup>–</jats:sup>, BF<jats:sub>4</jats:sub><jats:sup>–</jats:sup> and CF<jats:sub>3</jats:sub>SO<jats:sub>3</jats:sub><jats:sup>–</jats:sup>) have been synthesized and fully characterized by single‐crystal X‐ray diffraction, Mössbauer spectroscopy and magnetic susceptibility measurements. Upon cooling, a trapped [high‐spin–low‐spin] state of the iron(II) centres is detected. Depending on the counterion, a pronounced thermal hysteresis is found. In one case, it was possible to observe a space group change that accompanies the spin transition. This is the first system showing spin crossover based on an oxadiazole ligand.</jats:p>