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Low-temperature lifetimes of metastable high-spin states in spin-crossover and in low-spin iron(II) compounds: The rule and exceptions to the rule
|Published in||Coordination Chemistry Reviews. 2006, vol. 250, no. 13-14, p. 1642-1652|
|Abstract||The high-spin → low-spin relaxation in spin-crossover compounds can be described as non-adiabatic multi-phonon process in the strong coupling limit, in which the low-temperature tunnelling rate increases exponentially with the zero-point energy difference between the two states. Based on the hypothesis that the experimental bond length difference between the high-spin and the low-spin state of not, vert, similar0.2 Å is also valid for low-spin iron(II) complexes, extrapolation of the single configurational coordinate model allows an estimate of the zero-point energy difference for low-spin complexes from kinetic data. DFT calculations on low-spin [Fe(bpy)3]2+ support the structural assumption. However, for low-spin [Fe(terpy)2]2+ the relaxation rate constant shows an anomalous behaviour in so far as it is more in line with spin-crossover systems. This is attributed to very anisotropic bond length changes associated with the spin state change, and the subsequent breakdown of the single mode model.|
|Keywords||Spin-crossover — Intersystem crossing — Radiationless relaxation — Density functional theory — Iron(II)-tris-2,2'-bipyridine — Iron(II)-bis-2,2':6',2″-terpyridine|
|Research group||Groupe Hauser|
|HAUSER, Andreas et al. Low-temperature lifetimes of metastable high-spin states in spin-crossover and in low-spin iron(II) compounds: The rule and exceptions to the rule. In: Coordination Chemistry Reviews, 2006, vol. 250, n° 13-14, p. 1642-1652. doi: 10.1016/j.ccr.2005.12.006 https://archive-ouverte.unige.ch/unige:3304|