Book ChapterDOI
Nature and dynamics of the spin-state interconversion in metal complexes
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In this article, the Bragg and Williams approximation of the Ising model is used to describe spin-state transitions in metal complexes which are driven by a change of temperature T or pressure p are always associated with a considerable reorganization of molecular geometry, the change involves metal-ligand bond lengths R, bond angles and a variation of ligand orientation.Abstract:
Spin-state transitions in metal complexes which are driven by a change of temperature T or pressure p are always associated with a considerable reorganization of molecular geometry. The change involves metal-ligand bond lengths R, bond angles, and a variation of ligand orientation. In particular, the elongation 4R by up to ∼ 10% occurring in the course of the LS → HS conversion produces an expansion of molecular volume ΔV ≌ 25 A3 per metal atom. The average crystal structure for given values of T and p is reproduced by the fractional occupancy of the individual structures of the high-spin (HS) and low-spin (LS) isomer. The transitions are reasonably well described by a number of theoretical models which are equivalent to the Bragg and Williams approximation of the Ising model. The dynamics of the spin-state transitions in solution, based on measurements by ultrasonic and photo-perturbation techniques, is in general rapid with rate constants between 4 × 105 and 3 × 108 s−1. Similar results are obtained for the spin conversion in solid complexes where the line shape analysis of Mossbauer spectra based on the theory of Blume and Tjon is applied. The dynamics may be rationalized employing one-dimensional cross sections through Gibbs free-energy surfaces G = G(R), an alternative being the comparison of the results with quantum-mechanical calculations for a radiationless non-adiabatic multiphonon process.read more
Citations
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Journal ArticleDOI
Fascinating electronic games in iron complexes
Philipp Gütlich,J. Jung +1 more
TL;DR: In this article, the authors focus on selected examples of "thermal spin crossover" in iron(II) complexes and switching between different spin states by irradiation with light of different wavelength (LIESST effect).
Journal ArticleDOI
Bethe lattice approach and relaxation dynamics study of spin-crossover materials
TL;DR: In this article, the authors investigated the dynamics of Prussian blue analogs and spin-crossover materials in the framework of a Blume-Emery-Griffiths (BEG) spin-1 model, where states ± 1 and 0 represent the high-spin (HS) state and the low-spin state, respectively.
Journal ArticleDOI
Static and Dynamical Aspects of a Phonon‐Induced Spin‐Crossover Transition – Local Equilibrium Approach
TL;DR: In this paper, a dynamical extension of the phonon-induced spin crossover (SC) transition model is presented, which allows obtaining the time evolution of the metastable high spin fraction at low temperature.
Journal ArticleDOI
The refrigerant capacity in spin-crossover materials: Application to [Fe(phen) 2 (NCS) 2 ]
P.J. von Ranke,B.P. Alho,E.P. Nóbrega,A. Caldas,V.S.R. de Sousa,M.V. Colaço,Lippy F. Marques,Gabriel M. Rocha,D.L. Rocco,P.O. Ribeiro +9 more
TL;DR: In this paper, the authors reported the refrigerant capacity of a spin-crossover material (Fe(phen)2(NCS)2 ) with a pressure change of ΔP = 1/kbar.
Journal ArticleDOI
A time-resolved infrared vibrational spectroscopic study of the photo-dynamics of crystalline materials.
Michael Towrie,Anthony W. Parker,Kate L. Ronayne,Katharine F. Bowes,Jacqueline M. Cole,Paul R. Raithby,John E. Warren +6 more
TL;DR: The use of a sensitive pump–probe time-resolved infrared spectrometer and sample handling techniques for studies of the ultrafast excited-state dynamics of crystalline materials are reported on.
References
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Book
The Theory of Transition-Metal Ions
TL;DR: In this paper, the strong-filed coupling scheme was proposed to overcome the weak-field coupling scheme in paramagnetic resonance, which was shown to be effective in the case of free atoms and ions.
Journal ArticleDOI
400. The determination of the paramagnetic susceptibility of substances in solution by nuclear magnetic resonance
Book ChapterDOI
The Continuum Theory of Lattice Defects
TL;DR: In this paper, the authors present a discussion on the continuum theory of lattice defects, which is the usual theory of elasticity modified to include internal stress, and discuss some of the background principles and illustrates them by specific examples.
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