The atypical hysteresis of [Fe(C6F5Tp)2]: Overlay of spincrossovers and symmetry-breaking phase transition
Résumé
The [Fe II (C6F5Tp)2] spin-crossover complex is an atypical molecular switch, which can be converted upon annealing between two archetypal spin-crossover behaviours: from an extremely gradual spin-crossover to a broad hysteretic spin-transition (of ca. 65 K). The hysteresis shows an uncommon "rounded shape" that is reproducible upon cycling temperature. In depth structural studies reveal a first crystal phase transition, which occurs upon melting and recrystallizing at high temperature. This first irreversible transition is associated with a radical change in the crystal packing. More importantly, the "rounded and broad" hysteretic transition is shown to occurs in a noncooperative SCO system and is associated with the occurrence of a symmetry-breaking phase transition that appears when roughly ca. 50% of the SCO complexes are switched.
Domaines
Chimie
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