Book ChapterDOI
Nature and dynamics of the spin-state interconversion in metal complexes
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TLDR
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
Molecular Spin Crossover Materials: Review of the Lattice Dynamical Properties
TL;DR: The lattice dynamical aspects of the spin crossover phenomenon in molecular solids are reviewed in this paper, showing intricate couplings between the electronic spin state of the molecules and the lattice properties.
Journal ArticleDOI
Guest Modulation of Spin‐Crossover Transition Temperature in a Porous Iron(II) Metal–Organic Framework: Experimental and Periodic DFT Studies
Daniel Aravena,Zulema Arcís Castillo,M. Carmen Muñoz,Ana B. Gaspar,Ko Yoneda,Ryo Ohtani,Akio Mishima,Susumu Kitagawa,Masaaki Ohba,José Antonio Real,Eliseo Ruiz +10 more
TL;DR: Calculated lattice parameters and bond distances in the empty host 1 and 1⋅Guest clathrates are in general agreement with the X-ray diffraction data, and a general correlation between experimental Tc and calculated LS-HS electronic energy gap was observed.
Journal ArticleDOI
Two-Step versus One-Step Spin Transitions in Iron(II) 1D Chain Compounds
Wolfgang Bauer,Wolfgang Scherer,Sandra Altmannshofer,Sandra Altmannshofer,Birgit Weber,Birgit Weber +5 more
TL;DR: In this paper, 11 iron(II) 1D coordination polymers with the general formula [FeLeq(Lax)]·solvent were synthesized and characterised, where Leq = (E,E)-{diethyl 2,2′-[1,2-phenylenebis(iminomethylidyne)]bis(3-oxobutanato) (2-)-N,N′,O3-O3, O3′} (L1) and solvent = MeOH, EtOH and toluene (T
Journal ArticleDOI
d → d Spectrum and High-Spin/Low-Spin Competition in d6 Octahedral Coordination Compounds: ab Initio Study of Potential Energy Curves
TL;DR: In this paper, the authors focused on the six lowest states of the d → d spectrum (three singlets, one quintet, and two triplets states) and the dependence of their energy on the metal−ligand equilibrium distance.
Journal ArticleDOI
[Fe(nsal2trien)]SCN, a new two-step iron(III) spin crossover compound, with symmetry breaking spin-state transition and an intermediate ordered state.
Bruno J. C. Vieira,Joana T. Coutinho,Isabel C. Santos,Laura C. J. Pereira,João C. Waerenborgh,Vasco Gama +5 more
TL;DR: The synthesis of the iron(III) complex of the hexadentate Schiff base ligand nsal2trien obtained from the condensation of triethylenetetramine and 2 equiv.
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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