Synthesis and magnetic properties of new dinuclear iron(II) complexes of a phenylene‐bridge shiff base analogue dinucleating ligand

Weber, Birgit; Kaps, Eike

doi:10.1002/hc.20108

Cited by 35 publications

(31 citation statements)

References 28 publications

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“…Pure N amido –Fe II bonds usually vary from 1.89235 to 2.085 Å36 and are shorter than the bonds found in complex 5 , which suggests a mixture of both pure N amido –Fe and pure N pyridine –Fe bonds in this complex. The N pyridine –Fe II distances in 5 lie in the range of bond lengths found in the literature (1.992–2.307 Å) 37,38…”

Section: Resultssupporting

confidence: 60%

First Row Transition Metal Aminopyridinates – the Missing Complexes

et al. 2009

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Lithiated 4‐methyl‐2‐[(trimethylsilyl)amino]pyridine (ApTMSH) undergoes a salt metathesis reaction with [ScCl3(thf)3] and FeCl3, at low temperature in thf, to yield the homoleptic complexes [Sc(ApTMS)3] (1) and [Fe(ApTMS)3] (2). An analogous reaction with MnCl2, CoCl2 and FeCl2 using two equivalents of 4‐tert‐butylpyridine (tBuPy) as additional donor ligand affords the structurally analogous cis complexes [Mn(ApTMS)2(tBuPy)2] (3), [Co(ApTMS)2(tBuPy)2] (4) and [Fe(ApTMS)2(tBuPy)2] (5). If FeCl2 is used without tBuPy, the highly symmetric trinuclear complex [Fe3(ApTMS)6Li2O] (6) is obtained. Furthermore, the use of ZnCl2 in a reaction with lithiated ApTMSH yields the dimeric complex [Zn2(ApTMS)4] (7) in which two ApTMS ligands bridge the two metals. All complexes have been characterised by X‐ray crystal structure analysis. To the best of our knowledge, complexes 1 and 2 and 5 are the first scandium and iron aminopyridinates, respectively, and complex 3 is the first manganese aminopyridinate complex which contains no additional anionic ligand. Complexes 4 and 7 are rare examples of cobalt and zinc aminopyridinates. This study proves that aminopyridinato ligands are highly universal ligands since they are able to stabilize early and late transition metals. Aminopyridinates of every first row transition metal are now available. The magnetic properties of all paramagnetic complexes were investigated. All complexes are high‐spin complexes and the trinuclear iron complex 6 exhibits a weak antiferromagnetic coupling.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Resultssupporting

confidence: 60%

First Row Transition Metal Aminopyridinates – the Missing Complexes

et al. 2009

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“…The spectra ( Supporting Information File 1 , Figure S3) reveal one quadrupole split doublet in each case with parameters for the quadrupole splitting Δ E Q and an isomer shift δ ( Supporting Information File 1 , Table S1) in the range expected for iron(II) HS complexes of this ligand type [ 55 ]. The steps and the incomplete spin crossover observed in the magnetic measurements could be due to inequivalent iron centres [ 56 – 57 ]. The Mössbauer spectra do not support this as no line broadening (FWHM Γ in Supporting Information File 1 , Table S1) is observed and the doublet is very symmetric in each case.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of [Fe(L_eq)(L_ax)]_ncoordination polymer nanoparticles using blockcopolymer micelles

Göbel¹,

Klimm²,

Puchtler³

et al. 2017

Beilstein J. Nanotechnol.

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Spin-crossover compounds are a class of materials that can change their spin state from high spin (HS) to low spin (LS) by external stimuli such as light, pressure or temperature. Applications demand compounds with defined properties concerning the size and switchability that are maintained when the compound is integrated into composite materials. Here, we report the synthesis of [Fe(Leq)(Lax)]n coordination polymer (CP) nanoparticles using self-assembled polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) micelles as template. Variation of the solvent (THF and toluene) and the rigidity of the axial ligand Lax (Lax = 1,2-di(pyridin-4-yl)ethane) (bpea), trans-1,2-di(pyridin-4-yl)ethene (bpee), and 1,2-di(pyridin-4-yl)ethyne) (bpey); Leq = 1,2-phenylenebis(iminomethylidyne)-bis(2,4-pentanedionato)(2−)) allowed the determination of the preconditions for the selective formation of nanoparticles. A low solubility of the CP in the used solvent and a high stability of the Fe–L bond with regard to ligand exchange are necessary for the formation of composite nanoparticles where the BCP micelle is filled with the CP, as in the case of the [FeLeq(bpey)]n@BCP. Otherwise, in the case of more flexible ligands or ligands that lead to high spin complexes, the formation of microcrystals next to the CP–BCP nanoparticles is observed above a certain concentration of [Fe(Leq)(Lax)]n. The core of the nanoparticles is about 45 nm in diameter due to the templating effect of the BCP micelle, independent of the used iron complex and [Fe(Leq)(Lax)]n concentration. The spin-crossover properties of the composite material are similar to those of the bulk for FeLeq(bpea)]n@BCP while pronounced differences are observed in the case of [FeLeq(bpey)]n@BCP nanoparticles.

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“…The averaged metal-ligand distances around the inner coordination sphere of Fe1 (Fe1-N eq : 2.09 Å, Fe1-O eq : 2.01 Å, Fe1-N ax : 2.25 Å) indicate a distorted, axially elongated octahedral environment, typical for HS iron(II) of this ligand type. [9,17,18,20,23] The averaged metal-ligand distances in the [FeN 4 O 2 ] coordination core of Fe2 (Fe2-N eq : 1.90 Å, Fe2-O eq : 1.93 Å, Fe2-N ax : 1.99 Å) are about 10 % shorter than those for the HS state, as discussed in the literature for iron(II) SCO complexes. [2] Especially, the pronounced reduction of the Fe-N ax distance (0.26 Å) in the direction of a more regular octahedral environment is indicative of LS iron(II).…”

Section: X-ray Structure Analysismentioning

confidence: 94%

Complete Two‐Step Spin‐Transition in a 1D Chain Iron(II) Complex with a 110‐K Wide Intermediate Plateau

et al. 2011

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Three new spin crossover compounds [FeL1(azpy)] (1), [FeL1(azpy)]·toluene [1(tol)] and [FeL2(azpy)] (2), where L1 and L2 are the tetradentate N2O22– coordinating Schiff base like ligands {diethyl (E,E)‐2,2′‐[1,2‐phenyl‐bis(iminomethylidyne)]bis[3‐oxobutanoate]‐(2‐)‐N,N′,O3,O3′} and {dimethyl(E,E)‐2,2′‐[1,2‐phenyl‐bis(iminomethylidyne)]bis[3‐oxobutanoate]‐(2‐)‐N,N′,O3,O3′}, respectively, and azpy = 4,4′‐azopyridine are presented. All compounds have been investigated by using T‐dependent susceptibility measurements, and different types of spin transitions are observed. In the case of 1 and 2, intermediate plateaus (γHS ≈ 0.5) with widths of 110 and 75 K, respectively, were observed, while for 1(tol) a gradual spin transition is obtained. Upon heating of 1(tol) above 390 K, a loss of the included solvent molecule toluene is observed, which results in a two‐step spin transition of the tempered sample similar to that of 1. Mössbauer spectra of 1, 1(tol) and the tempered sample 1(temp) reveal two different iron(II) sites in the low‐spin (LS) state for all three samples. T‐dependent Mössbauer spectra indicate that the inequivalent iron centres are one but not the only reason for the wide plateau of 1. Results from X‐ray structure analysis of 1 in the region of the plateau show the presence of two inequivalent iron centres, of which one is in the high‐spin (HS) state and one in the low‐spin state. The 1D chains of alternating HS and LS iron centres are arranged in a parallel manner within one layer; between the different layers, the direction of the chains rotates by 90° relative to the previous one. This cross‐linked arrangement with an interlocking of the layers is most likely the reason for the appearance of the wide plateau.

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Synthesis and magnetic properties of new dinuclear iron(II) complexes of a phenylene‐bridge shiff base analogue dinucleating ligand

Abstract: The synthesis and magnetic behavior of four new dinuclear iron(II) complexes

Cited by 35 publications

References 28 publications

First Row Transition Metal Aminopyridinates – the Missing Complexes

First Row Transition Metal Aminopyridinates – the Missing Complexes

Synthesis of [Fe(L_eq)(L_ax)]_ncoordination polymer nanoparticles using blockcopolymer micelles

Complete Two‐Step Spin‐Transition in a 1D Chain Iron(II) Complex with a 110‐K Wide Intermediate Plateau

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Synthesis and magnetic properties of new dinuclear iron(II) complexes of a phenylene‐bridge shiff base analogue dinucleating ligand

Abstract: The synthesis and magnetic behavior of four new dinuclear iron(II) complexes

Cited by 35 publications

References 28 publications

First Row Transition Metal Aminopyridinates – the Missing Complexes

First Row Transition Metal Aminopyridinates – the Missing Complexes

Synthesis of [Fe(Leq)(Lax)]ncoordination polymer nanoparticles using blockcopolymer micelles

Complete Two‐Step Spin‐Transition in a 1D Chain Iron(II) Complex with a 110‐K Wide Intermediate Plateau

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Synthesis of [Fe(L_eq)(L_ax)]_ncoordination polymer nanoparticles using blockcopolymer micelles