Light-induced excited spin state trapping in iron(iii) complexes

This review discusses the correlation of the local and whole molecular structure of iron(iii) complexes with the magnetic properties including the light-induced excited spin-state trapping (LIESST) effect.

Spin Crossover in 3D Metal Centers Binding Halide-Containing Ligands: Magnetism, Structure and Computational Studies

The capability of a given substance to change its spin state by the action of a stimulus, such as a change in temperature, is by itself a very challenging property. Its interest is increased by the potential applications and the need to find sustainable functional materials. 3D transition metal complexes, mainly with octahedral geometry, display this property when coordinated to particular sets of ligands. The prediction of this behavior has been attempted by many authors. It is, however, made very difficult because spin crossover (SCO), as it is called, occurs most often in the solid state, where besides complexes, counter ions, and solvents are also present in many cases. Intermolecular interactions definitely play a major role in SCO. In this review, we decided to analyze SCO in mono- and binuclear transition metal complexes containing halogens as ligands or as substituents of the ligands. The aim was to try and find trends in the properties which might be correlated to halogen substitution patterns. Besides a revision of the properties, we analyzed structures and other information. We also tried to build a simple model to run Density Functional Theory (DFT) calculations and calculate several parameters hoping to find correlations between calculated indices and SCO data. Although there are many experimental studies and single-crystal X-ray diffraction structures, there are only few examples with the F, Cl, Br and series. When their intermolecular interactions were not very different, T1/2 (temperature with 50% high spin and 50% low spin states) usually increased with the calculated ligand field parameter (Δoct) within a given family. A way to predict SCO remains elusive.

The substituent guest effect on four-step spin-crossover behavior

The fluoro substituent strategy on the guest in a three-dimensional Hofmann-type metal–organic framework is explored for four-step spin-crossover properties.

Spin-crossover behavior of neutral iron(iii) complexes with salicylaldehyde thio-, seleno- and semicarbazone ligands: experiment and theoretical analysis

A novel neutral complex [Fe^III(Hsemsal)(semsal)]·3H₂O was synthesized and its magnetic properties, and crystal and electronic structures were studied.

Tuning the spin crossover behavior of the polyanion [(H2O)6Fe3(μ-L)6]6–: the case of the cesium salt

Cation exchange transforms the gradual spin transition of the trimer [(H₂O)₆Fe₃(μ-L)₆]^6– into an abrupt transition with a wide hysteresis above room temperature.

Solvatomorphism and anion effects in predominantly low spin iron(iii) Schiff base complexes

The magnetic properties of a series of iron(iii) complexes [Fe(naphEen)₂]halide·sol are reported.

Spin crossover in mixed ligand iron(iii) complexes

The use of two subtly different ligands is used to explore their impact on spin crossover characteristics.

Iron(iii) complexes of 2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol as spin-crossover molecular materials

Four new mononuclear Fe(iii) complexes are obtained by using 2-methyl-6-(pyrimidin-2-yl-hydrazonomethyl)-phenol. The perchlorate complex displays spin crossover with a hysteresis of 32 K, while the neutral complex exhibits a gradual incomplete spin transition.

Structural characterization, phase transition and switchable dielectric behaviors in a new zigzag chain organic–inorganic hybrid compound: [C3H7NH3]2SbI5

A new zigzag chain organic–inorganic hybrid compound with the general formula R₂MI₅, [n-C₃H₇NH₃]₂[SbI₅], exhibits a switchable dielectric character.

Crystal structures, phase transitions, and switchable dielectric behaviors: comparison of a series of N-heterocyclic ammonium perchlorates

1-Propyl-1-methylpiperidinium, 1-cyanomethyl-1-methylpiperidinium and 1-cyanomethyl-1-methylmorpholinium perchlorates display switchable dielectric responses accompanied by phase transitions at around 199, 387 and 416 K, respectively.

Two-step spin crossover behaviour in the chiral one-dimensional coordination polymer [Fe(HAT)(NCS)2]∞

Two-step spin crossover behaviour with large stabilisation of the intermediate state in a chiral one-dimensional coordination polymer.