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
Competing Phases Involving Spin-State and Ligand Structural Orderings in a Multistable Two-Dimensional Spin Crossover Coordination Polymer
Daopeng Zhang,Daopeng Zhang,Elzbieta Trzop,Francisco Javier Valverde-Muñoz,Lucía Piñeiro-López,M. Carmen Muñoz,Eric Collet,José Antonio Real +7 more
TL;DR: In this paper, competition between spin crossover and structural ligand ordering is identified as responsible for multistability and generation of six different phases in a rigid two-dimensional coordination polymer formulated.
Journal ArticleDOI
Thermal‐, Pressure‐ and Light‐Induced Spin‐Crossover Behaviour in the Two‐Dimensional Hofmann‐Like Coordination Polymer [Fe(3‐Clpy)2Pd(CN)4]
Víctor Martínez,Víctor Martínez,Zulema Arcís Castillo,M. Carmen Muñoz,Ana B. Gaspar,Céline Etrillard,Céline Etrillard,Jean-François Létard,Jean-François Létard,Sergey A. Terekhov,Gennadiy Bukin,Georgiy Levchenko,José Antonio Real +12 more
TL;DR: In this article, the thermal spin-crossover behavior, photoexcitation and subsequent relaxation, as well as the pressure-induced spincrossover behaviour at 298 K are discussed for the nonporous two-dimensional Hofmann-like coordination polymer [Fe(3-Clpy)2Pd(CN)4] (1).
Journal ArticleDOI
[FeII(TRIM)2]F2, the First Example of Spin Conversion Monitored by Molecular Vibrations
Azzedine Bousseksou,Marc Verelst,Hector Constant-Machado,Gilles Lemercier,Jean-Pierre Tuchagues,François Varret +5 more
TL;DR: A theoretical approach based on the Ising-like model, completed with harmonic oscillators associated with the 15 vibration modes of the FeN(6) coordination octahedron, successfully fits the data with an energy gap of approximately 40 K between the lowest LS and HS electrovibrational states.
Journal ArticleDOI
Processable magnetic plastics composites—spin crossover of PMMA/Fe(II)-complexes composites
TL;DR: In this paper, three new Fe(II) complexes containing 4-heptyl-1,2,4-triazole ligand and various counterions such as ClO 4 −, BF 4 − and Br − were blended with PMMA and spin crossover behavior of the composites were studied by using a superconducting quantum interference device (SQUID) and differential scanning calorimetry (DSC).
Journal ArticleDOI
Theoretical Investigation of the Effect of a Spin Transition on the Second-Order Molecular Hyperpolarizability of a Bis(salicylaldiminato)FeII Schiff Base Complex
TL;DR: In this article, the effect of spin-crossovers on density functional theory and differential overlap-based (INDO-based) sum-over-state perturbution theory is explored.
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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