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
From Magnetic to Nonlinear Optical Switches in Spin‐Crossover Complexes
Pascal G. Lacroix,Pascal G. Lacroix,Isabelle Malfant,Isabelle Malfant,José Antonio Real,Vincent Rodriguez +5 more
TL;DR: In this article, a review of magnetic and nonlinear optical properties in a molecule is presented, with a special focus on the possibility of interplay between the magnetic component and the quadratic (prop] E2) NLO response.
Journal ArticleDOI
A spin-crossover iron(II) coordination polymer with the 8-aminoquinoline ligand: synthesis, crystal structure and magnetic properties of [Fe(aqin)2(4,4′-bpy)](ClO4)2·2EtOH (aqin = 8-aminoquinoline, 4,4′-bpy = 4,4′-bipyridyl)
TL;DR: In this paper, the synthesis and characterisation of a new iron(II) spin-crossover coordination polymer with a linear chain structure was reported. But the structure was not characterized.
Journal ArticleDOI
Spin crossover in mononuclear and binuclear iron(III) complexes with pentadentate Schiff-base ligands
Roman Boča,Yutaka Fukuda,Milan Gembický,Radovan Herchel,Rastislav Jaroščiak,Wolfgang Linert,Franz Renz,Jyunko Yuzurihara +7 more
TL;DR: A series of mononuclear hexacoordinate iron(III) complexes, [Fe( 5 L )(py)]BPh 4, has been prepared and their magnetic properties were investigated; the pentadentate ligands were derivatives of 5 L =saldptn=N,N′-bis(2-hydroxybenzyliden)-1,7-diamino-4-azaheptane.
Journal ArticleDOI
Established Static Models of Spin Crossover
Ján Pavlik,Roman Boča +1 more
TL;DR: In this article, various models describing the stationary temperature-induced phenomenon of spin crossover in metal complexes are briefly discussed and the emphasis is put on the usability of the presented models as tools for the quantitative interpretation of experimental data.
Journal ArticleDOI
Parallel Crystallization of a “Static” and a Spin-Crossover Polymorph of an Iron(II) Complex from the Same Solution
Marco Haryono,Frank W. Heinemann,Konstantin Petukhov,Klaus Gieb,Paul Müller,Andreas Grohmann +5 more
TL;DR: In this article, the ligand 2,6-bis(1H-pyrazol-1-yl)-4-(thiocyanatomethyl)pyridine (L) has been prepared from the hydroxymethyl precursor by OH/Br exchange and subsequent substitution.
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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