High-spin to low-spin relaxation kinetics in the [Fe(TRIM)2]Cl2 complex

Sébastien Bonhommeau (1, 2) , Nicolas Bréfuel (1) , Villö K. Pálfi (1, 3) , Gábor Molnár (1) , Antoine Zwick (2) , Lionel Salmon (4, 5) , Jean-Pierre Tuchagues (1) , José Sánchez Costa (6) , Jean-François Létard (6) , Hauke Paulsen (7) , Azzedine Bousseksou (1)

1 LCC - Laboratoire de chimie de coordination
2 Laboratoire Physique des Solides de Toulouse
3 Institute of Chemistry [Budapest]
4 LCF - URA 331 - Laboratoire Claude Fréjacques
5 DRECAM - Département de Recherche sur l'Etat Condensé, les Atomes et les Molécules
6 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
7 Institute of Physics

A quasi-quantitative photo-induced low-spin (LS) -> high-spin (HS) conversion of FeII ions has been observed in the [Fe(TRIM)2]Cl2 complex by irradiating the sample with blue light (488 nm) at 10 K. The time dependence of the HS -> LS relaxation has been studied between 10 K and 44 K by means of magnetic susceptibility measurements. These relaxation curves could be satisfactorily fitted by mono-exponential decays including tunnelling effect except for temperatures below 30 K. The introduction of a distribution of vibrational frequencies into this model improved significantly the fits in the low-temperature range and gave a good agreement with the experimental data in the whole temperature range suggesting a multi-rate relaxation process in this complex.

Mots clés: [Fe(TRIM)2]Cl2; Relaxations; High spin; Low spin; Complex compounds

Domaines: Matériaux

Sébastien Bonhommeau, Nicolas Bréfuel, Villö K. Pálfi, Gábor Molnár, Antoine Zwick, et al.. High-spin to low-spin relaxation kinetics in the [Fe(TRIM)2]Cl2 complex. Physical Chemistry Chemical Physics, 2005, vol. 7, n° 15, p. 2909-2914. ⟨10.1039/b504614a⟩. ⟨hal-00097921⟩