"Normal" and "reverse" spin crossover induced by two different structural events in iron(ii) coordination polymer.

In [Fe(ebbtr)2(CH3CN)2](CF3SO3)2·4CH3CN spin crossover is associated with the occurrence of "normal" and "reverse" hysteresis loops separated by a region of stable HS form. This results from trans-trans → gauche-trans conformational changes of ebbtr molecules and anion reorientation, which occur in different ways during cooling and during heating.