Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands

Martinho, Paulo N.; Vicente, Ana I.; Realista, Sara; Saraiva, Marta S.; Melato, A.I.; Brandão, Paula; Ferreira, Liliana P.; Carvalho, Maria Graça

doi:10.1016/j.jorganchem.2013.12.028

Cited by 21 publications

(15 citation statements)

References 51 publications

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“…Martinho et al studied [112] the mono-bromo and di-bromo salEen (L22, Scheme 4) Fe(III) perchlorate and tetraphenylborate salts in acetonitrile solutions by NMR, UV-vis and cyclic voltammetry. The magnetic susceptibility was determined by the Evans method in deuterated acetonitrile solutions and the χ M T values were consistent with a mixture of both HS and LS states for both complexes, the di-bromo compounds having the major LS fraction.…”

Section: Results Solutionmentioning

confidence: 99%

“…The same comparison cannot be made for the NCS − complexes because with L Br the structure is totally different, but the trend also holds for Cl (HS for L Br ). Martinho and co-workers [112] reported the synthesis of two salts of the 3,5-Br-salEen ligand (3,5-Br-salEen = N-ethyl-N-(2-aminoethyl)-3,5-Br-salicylaldiminate) (L22, R 1 = R 2 = Br), [Fe(L22) 2 ]X.sol. The perchlorate was obtained as an ethanol solvate and was found to remain LS over the temperature range measured.…”

Section: Methodsmentioning

confidence: 99%

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

2020

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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.

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Section: Results Solutionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

2020

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“…As part of our interest in Fe(III) SCO systems, 22 we have recently found that a compound previously reported by us, [Fe(5-Br-salEen) 2 ]ClO 4 (Scheme 1), 23 can be selectively obtained in two distinct polymorphic phases. In this work, the synthesis and characterization of the new polymorph and the attempts to both understand and selectively control their synthesis are fully explored.…”

Section: Introductionmentioning

confidence: 90%

Selecting the spin crossover profile with controlled crystallization of mononuclear Fe(iii) polymorphs

et al. 2018

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Two polymorphic species of the [Fe(5-Br-salEen)2]ClO4 compound were obtained, each of them being selectively recovered after evaporation of the solvent at a controlled rate. While polymorph 1a is formed during slow evaporation, fast evaporation favors polymorph 1b. The importance of the evaporation rate was recognized after detailed studies of the reaction temperature, solvent evaporation rate and crystallization temperature effects. The complex in the new polymorphic form 1a showed an abrupt spin crossover at 172 K with a small 1 K hysteresis window and over a narrow 10 K range. 57Fe Mössbauer spectroscopy and differential scanning calorimetry, complemented by X-ray studies for both the high-spin and low-spin forms, were used to further characterize the new polymorphic phase 1a. Both polymorphs are based on the same Fe(iii) complex cation hydrogen bonded to the perchlorate anion. These units are loosely bound in the crystals via weak interactions. In the new polymorph 1a, the hydrogen bonds are stronger, while the weak hydrogen and halogen bonds, as well as π-π stacking, create a cooperative network, not present in 1b, responsible for the spin transition profile.

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“…Crystals of the family of [Fe(R-salEen) 2 ]X complexes are one of the most representative series exhibiting SCO behaviors studied in detail, except for the thermal conductivity. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] In this work, four derivatives having solvent-free crystals with the potential to be grown into a sufficiently large size for the measurement of thermal conductivity were selected. Herein, the crystal structures, magnetic properties, thermal conductivities, and estimates of the phonon velocity and the mean free path of phonons of the four Fe(III) SCO complexes [Fe(R-salEen) 2 ]X 2 (Fig.…”

Section: Introductionmentioning

confidence: 99%

The strong correlations between thermal conductivities and electronic spin states in the crystals of Fe(iii) spin crossover complexes

2022

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Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands

Cited by 21 publications

References 51 publications

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

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

Selecting the spin crossover profile with controlled crystallization of mononuclear Fe(iii) polymorphs

The strong correlations between thermal conductivities and electronic spin states in the crystals of Fe(iii) spin crossover complexes

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