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The Atypical Hysteresis of [Fe(C 6 F 5 Tp) 2 ]: Overlay of Spin‐Crossovers and Symmetry‐Breaking Phase Transition
Author(s) -
Benchohra Amina,
Li Yanling,
Chamoreau LiseMarie,
Baptiste Benoit,
Elkaïm Erik,
Guillou Nathalie,
Kreher David,
Lescouëzec Rodrigue
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202015994
Subject(s) - spin crossover , spin transition , hysteresis , phase transition , condensed matter physics , annealing (glass) , crystal (programming language) , chemistry , materials science , chemical physics , crystallography , physics , computer science , composite material , programming language
The [Fe II (C 6 F 5 Tp) 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 occur in a non‐cooperative 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.