Iron(III) complexes with pentadentate Schiff-base ligands: Influence of crystal packing change and pseudohalido coligand variations on spin crossover

Krüger, Christoph; Augustín, Peter; Dlháň, Ľubor; Pavlík, Jan; Moncóľ, Ján; Němec, Ivan; Boča, Roman; Renz, Franz

doi:10.1016/j.poly.2014.11.014

Cited by 36 publications

(36 citation statements)

References 46 publications

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“…Pavlik et al reported [111] similar pentadentate ligands (L21) with bromo substituents on the phenolate, which form octahedral Fe(III) complexes, [Fe(L Br )X], with addition of another ligand (X=halides or pseudo-halides). The Cl derivative was obtained as a water solvate, the N 3 as a methanol solvate, and the others crystallized without solvent.…”

Section: Methodsmentioning

confidence: 99%

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: Methodsmentioning

confidence: 99%

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

2020

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“…These complexes are also beneficial for the construction of polynuclear materials such as di [33][34][35][36][37][38][39][40][41][42], tri [43], tetra [44], penta [45], hepta [46][47][48], nona [48] and dodecanuclear [49] complexes by using bridging ligands instead of monodentate ligands for exhibiting multi-step spin transition. In the pentadentate ligand system, although iron(III) SCO compounds are well known [50][51][52][53][54][55][56][57], iron(II) spin transition systems are quite rare [58,59]. One of the reasons for this is the difficulty of the crystallization of iron(II) complexes with pentadentate ligand, as pointed out by Matsumoto et al [60].…”

Section: Introductionmentioning

confidence: 99%

Iron(II) Spin Crossover Complex with the 1,2,3-Triazole-Containing Linear Pentadentate Schiff-Base Ligand and the MeCN Monodentate Ligand

et al. 2019

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A mononuclear iron(II) complex bearing the linear pentadentate N5 Schiff-base ligand containing two 1,2,3-triazole moieties and the MeCN monodentate ligand, [FeIIMeCN(L3-Me-3Ph)](BPh4)2·MeCN·H2O (1), have been prepared (L3-Me-3Ph = bis(N,N′-1-Phenyl-1H-1,2,3-triazol-4-yl-methylideneaminopropyl)methylamine). Variable-temperature magnetic susceptibility measurements revealed an incomplete one-step spin crossover (SCO) from the room-temperature low-spin (LS, S = 0) state to a mixture of the LS and high-spin (HS, S = 2) species at the higher temperature of around 400 K upon first heating, which is irreversible on the consecutive cooling mode. The magnetic modulation at around 400 K was induced by the crystal-to-amorphous transformation accompanied by the loss of lattice MeCN solvent, which was evident from powder X-ray diffraction (PXRD) studies and themogravimetry. The single-crystal X-ray diffraction studies showed that the complex is in the LS state (S = 0) between 296 and 387 K. In the crystal lattice, the complex-cations and B(1)Ph4− ions are alternately connected by intermolecular CH···π interactions between the methyl group of the MeCN ligand and phenyl groups of B(1)Ph4− ions, forming a 1D chain structure. The 1D chains are further connected by P4AE (parallel fourfold aryl embrace) interactions between two neighboring complex-cations, constructing a 2D extended structure. B(2)Ph4− ions and MeCN lattice solvents exist in the spaces of the 2D layer. DFT calculations verified that the 1,2,3-triazole-containing ligand L3-Me-3Ph gives a stronger ligand field around the octahedral coordination environment of the iron(II) ion than the analogous imidazole-containing ligand H2L2Me (= bis(N,N′-2-methylimidazol-4-yl-methylideneaminopropyl)methylamine) of the known compound [FeIIMeCN(H2L2Me)](BPh4)1.5·Cl0.5·0.5MeCN (2) reported by Matsumoto et al. (Nishi, K.; Fujinami, T.; Kitabayashi, A.; Matsumoto, N. Tetrameric spin crossover iron(II) complex constructed by imidazole⋯chloride hydrogen bonds. Inorg. Chem. Commun. 2011, 14, 1073–1076), resulting in the much higher spin transition temperature of 1 than that of 2.

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“…Abbreviations: L = salpet, L Cl = 5-Cl-salpet, L Br = 5-Br-salpet, L m = 3-MeO-salpet, L e = 3-EtO-salpet. References: KRÜGER et al, 2013;KRÜGER et al, 2015;MASÁROVÁ et al, 2015;NEMEC et al, 2011;ŠALITROŠ et al, 2009. The SQUID magnetometer (Quantum Design, MPMS-XL7) was used for measurements of the magnetic data (temperature dependence of the magnetic susceptibility, and field dependence of the magnetization). The magnetic data for Fe III complexes referring either to the low-spin (LS) or the high-spin (HS) state was analyzed in terms of the Curie-Weiss law; to this end the g-factor, Weiss constant Θ, and the van Vleck term α were obtained.…”

Section: Methodsmentioning

confidence: 99%

“…for ligands: saldptn = N,N'-bis(2-hydroxybenzyliden)-1,7-diamino-4-azaheptane, napet = N,N'-bis(2-hydroxynapthylidene)-1,6-diamino-4-azahexane. References: BOČA et al, 2000;KRÜGER et al, 2013;KRÜGER et al, 2015;MASÁROVÁ et al, 2015;NEMEC et al, 2011;ŠALITROŠ et al, 2009.…”

Section: Methodsmentioning

confidence: 99%

“…It was reported recently that the spin transition can be tuned by varying coligands in the basic skeleton of the complexes of [Fe III L 5 X] type; here L 5 stands for a pentadentate Schiff base whereas X − is a monodentate pseudohalido coligand (KRÜGER et al, 2013;KRÜGER et al, 2015;MASÁROVÁ et al, 2015;NEMEC et al, 2011;ŠALITROŠ et al, 2009). Although chemists try to rationalize ΔH by changing the ligand field strength, the aspects influencing the ΔS cofactor are unclear so far.…”

Section: Introductionmentioning

confidence: 99%

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Magnetostructural Relationships For Fe(III) Spin Crossover Complexes

Augustín¹,

Boča²

2015

Nova Biotechnologica Et Chimica

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Structural data for fifteen complexes of Fe(III) of a general formula [FeL 5 X], with pentadentate Schiff-base ligands L 5 and unidentate coligands X − , were subjected to a statistical analysis. The multivariate methods such as Pearson correlation, cluster analysis and principal component analysis split the data into two clusters depending upon the low-spin and/or high-spin state of the complex at the temperature of the X-ray experiment. Some of these complexes exhibit a thermally induced spin crossover. The numerical analysis of the magnetic susceptibility and magnetization data for an enlarged set of Fe(III) spin crossover systems yields the enthalpy ΔH and entropy ΔS of the transition along with the transition temperature T 1/2 and the solid state cooperativeness. The thermodynamic data show a mutual relationship manifesting itself by linear ΔS vs ΔH and T 1/2 vs ΔH correlations.

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Iron(III) complexes with pentadentate Schiff-base ligands: Influence of crystal packing change and pseudohalido coligand variations on spin crossover

Cited by 36 publications

References 46 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

Iron(II) Spin Crossover Complex with the 1,2,3-Triazole-Containing Linear Pentadentate Schiff-Base Ligand and the MeCN Monodentate Ligand

Magnetostructural Relationships For Fe(III) Spin Crossover Complexes

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