Slow Dynamics of the Spin-Crossover Process in an Apparent High-Spin Mononuclear Fe(II) Complex

Yi Shan Ye (1) , Xiu Qin Chen , You De Cai , Bin Fei , Pierre Dechambenoit (2) , Mathieu Rouzieres (2) , Corine Mathonière (3) , Rodolphe Clérac (2) , Xin Bao (1)

1 NJUST - Nanjing University of Science and Technology
2 CRPP - Centre de Recherche Paul Pascal
3 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

A mononuclear FeII complex that shows a high‐spin (S=2) paramagnetic behavior at all temperatures (with standard temperature‐scan rates, ≈1 K min−1) has, in fact, a low‐spin (S=0) ground state below 100 K. This low‐spin state is not easily accessible due to the extremely slow dynamics of the spin‐crossover process—a full relaxation from the metastable high‐spin state to the low‐spin ground state takes more than 5 h below 80 K. Bidirectional photo‐switching of the FeII state is achieved reproducibly by two selective irradiations (at 530–590 and 830–850 nm). The slow dynamics of the spin‐crossover and the strong structural cooperativity result in a remarkably wide 95‐K hysteresis loop induced by both temperature and selected light stimuli.

Domaines: Chimie de coordination

Yi Shan Ye, Xiu Qin Chen, You De Cai, Bin Fei, Pierre Dechambenoit, et al.. Slow Dynamics of the Spin-Crossover Process in an Apparent High-Spin Mononuclear Fe(II) Complex. Angewandte Chemie International Edition, 2019, 58 (52), pp.18888-18891. ⟨10.1002/anie.201911538⟩. ⟨hal-02418828⟩