Spin Crossover in Polymeric Materials Using Schiff Base Functionalized Triazole Ligands

Scott, Hayley S.; Ross, Tamsyn Maree; Moubaraki, Boujemaa; Murray, Keith S.; Neville, Suzanne M.

doi:10.1002/ejic.201201071

Cited by 21 publications

(20 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With regard to superexchange interactions in these compounds, the coupling parameters extracted are of the same order as those reported for other M‐(trz) 3 ‐M‐bridged compounds,20g, 22a,b and we also found the same trend with stronger antiferromagnetic interactions in the Ni 2+ derivative23 and very weak interactions for the Cu 2+ complex. Still, a better understanding of the magnetic behavior of these molecules could be achieved with, for example, additional data from EPR measurements.…”

Section: Discussionsupporting

confidence: 84%

See 1 more Smart Citation

Hysteretic Spin Crossover above Room Temperature and Magnetic Coupling in Trinuclear Transition‐Metal Complexes with Anionic 1,2,4‐Triazole Ligands

Gómez

Benet‐Buchholz

Martín

et al. 2014

Chemistry A European J

View full text Add to dashboard Cite

The reaction of 4-(1,2,4-triazol-4-yl)ethanesulfonate (L) with Zn(2+), Cu(2+), Ni(2+), Co(2+), and Fe(2+) gave a series of analogous neutral trinuclear complexes with the formula [M3(μ-L)6(H2O)6] (1-5). These compounds were characterized by single-crystal X-ray diffraction, thermogravimetry, and elemental analysis. The magnetic properties of compounds 2-5 were studied. Complexes 2-4 show weak antiferromagnetic superexchange, with J values of -0.33 (2), -9.56 (3), and -4.50 cm(-1) (4) (exchange Hamiltonian H = -2 J (S1S2+S2S3)). Compound 5 shows two additional crystallographic phases (5 b and 5 c) that can be obtained by dehydration and/or thermal treatment. These three phases exhibit distinct magnetic behavior. The Fe(2+) centers in 5 are in high-spin (HS) configuration at room temperature, with the central one exhibiting a non-cooperative gradual spin transition below 250 K with T1/2 = 150 K. In 5 b, the central Fe(2+) stays in its low-spin (LS) state at room temperature, and cooperative spin transition occurs at higher temperatures and with the appearance of memory effect (T1/2↑ = 357 K and T1/2↓ = 343 K). In the case of 5 c, all iron centers remain in their HS configuration down to very low temperatures, with weak antiferromagnetic coupling (J = -1.16 cm(-1)). Compound 5 b exhibits spin transition with memory effect at the highest temperature reported, which matches the remarkable features of coordination polymers.

show abstract

Section: Discussionsupporting

confidence: 84%

“…The values of J is in very good agreement with superexchange interactions found for analogous trz‐bridged HS Fe 2+ complexes 20g. 22a,b, 23…”

Section: Resultsmentioning

confidence: 99%

Hysteretic Spin Crossover above Room Temperature and Magnetic Coupling in Trinuclear Transition‐Metal Complexes with Anionic 1,2,4‐Triazole Ligands

Gómez

Benet‐Buchholz

Martín

et al. 2014

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…The corresponding χ M −1 vs. T plot shows a linear Curie-Weiss ( χ M = C/(T − θ)) dependence with θ = −32 K and C = 3.8 cm 3 mol −1 K. Although, overall, the χ M T values decrease with decreasing temperature this behaviour is likely due to weak antiferromagnetic exchange occurring between adjacent iron(II) centres in the 1D-chain rather than to a broad spin transition. We, 13 and others, 17 have recently noted similar antiferromagnetic coupling in related 1D HS triply triazolebridged Fe II complexes. Mössbauer spectral analyses at 300 K and 77 K on complex 2 (Fig.…”

Section: Magnetic Susceptibility and Mössbauer Effect Measurementssupporting

confidence: 71%

A ferrocenyl-substituted 1,2,4-triazole ligand and its FeII, NiII and CuII 1D-chain complexes

et al. 2013

Self Cite

View full text Add to dashboard Cite

As part of a program aimed at making bifunctional iron(II) spin-crossover (SCO) materials, particularly those having redox/electron transfer as the second function, we have made the new ferrocene-triazole ligand ATF ([(4H-1,2,4-triazol-4-yl)amino]methylferrocene), (1), and a series of M(II) complexes of this ligand with emphasis on iron(II). Polynuclear 1D-chain complexes [Fe(ATF)3](Br)2·0.5(H2O) (2), [Fe(ATF)3](ClO4)2·0.5(H2O) (3), [Ni(ATF)3](ClO4)2·0.5(H2O) (4) and an analogous complex formed with a positively charged ATF ligand [Fe(ATF(+))3](ClO4)5 (6) were formed as polycrystalline powders. Crystals of a mixed ATF/NCS-bridged copper(II) polymer [Cu(ATF)2(NCS)](ClO4)·(Et2O)0.5(MeCN) (5) were formed and structurally characterised. Magnetic and Mössbauer spectral measurements on 2, 3 and 6 indicated that SCO has not been achieved though the Mössbauer data show interesting temperature dependence for doublets of the two iron sites for complexes 2 and 3. Solid state cyclic voltammetric data on the iron(II) complexes 3 and 4 showed well defined, reversible ATF-based electrochemistry, similar to those shown by ATF in solution.

show abstract

“…The subtleties of the effects of solvent molecules on the spin-transition phenomenon are highlighted in a study performed by Kruger and co-workers who presented a pair of solvatomorphs of a Fe(II) dinuclear triple helicate structure that demonstrated a half-transition when incorporating water molecules of crystallisation and a full asymmetric spin-crossover when acetonitrile molecules were present in the crystal lattice [51,54]. Two independent studies were performed by Garcia et al [55] and Neville et al [56] on two pseudopolymorphs of the complex [Fe II 2 (A) 5 (cis-NCS) 4 ]nMeOH, where n = 4 and 2 respectively and A = N-salicylidene 4-amino-1,2,4-triazole. The first presented a monoclinic structure with a T 1/2 of 155 K, while the latter yielded a triclinic structure with no SCO taking place.…”

Section: Introductionmentioning

confidence: 99%

Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds

et al. 2018

View full text Add to dashboard Cite

This work explores the effect of lattice solvent on the observed solid-state spin-transition of a previously reported dinuclear Fe(II) triple helicate series 1–3 of the general form [FeII2L3](BF4)4(CH3CN)n, where L is the Schiff base condensation product of imidazole-4-carbaldehyde with 4,4-diaminodiphenylmethane (L1), 4,4′-diaminodiphenyl sulfide (L2) and 4,4′-diaminodiphenyl ether (L3) respectively, and 1 is the complex when L = L1, 2 when L = L2 and 3 when L = L3 (Craze, A.R.; Sciortino, N.F.; Bhadbhade, M.M.; Kepert, C.J.; Marjo, C.E.; Li, F. Investigation of the Spin Crossover Properties of Three Dinuclear Fe(II) Triple Helicates by Variation of the Steric Nature of the Ligand Type. Inorganics. 2017, 5 (4), 62). Desolvation of 1 and 2 during measurement resulted not only in a decrease in T1/2 and completeness of spin-crossover (SCO) but also a change in the number of steps in the spin-profile. Compounds 1 and 2 were observed to change from a two-step 70% complete transition when fully solvated, to a single-step half complete transition upon desolvation. The average T1/2 value of the two-steps in the solvated materials was equivalent to the single T1/2 of the desolvated sample. Upon solvent loss, the magnetic profile of 3 experienced a transformation from a gradual SCO or weak antiferromagnetic interaction to a single half-complete spin-transition. Variable temperature single-crystal structures are presented and the effects of solvent molecules are also explored crystallographically and via a Hirshfeld surface analysis. The spin-transition profiles of 1–3 may provide further insight into previous discrepancies in dinuclear triple helicate SCO research reported by the laboratories of Hannon and Gütlich on analogous systems (Tuna, F.; Lees, M. R.; Clarkson, G. J.; Hannon, M. J. Readily Prepared Metallo-Supramolecular Triple Helicates Designed to Exhibit Spin-Crossover Behaviour. Chem. Eur. J. 2004, 10, 5737–5750 and Garcia, Y.; Grunert, C. M.; Reiman, S.; van Campenhoudt, O.; Gütlich, P. The Two-Step Spin Conversion in a Supramolecular Triple Helicate Dinuclear Iron(II) Complex Studied by Mössbauer Spectroscopy. Eur. J. Inorg. Chem. 2006, 3333–3339).

show abstract

Spin Crossover in Polymeric Materials Using Schiff Base Functionalized Triazole Ligands

Cited by 21 publications

References 25 publications

Hysteretic Spin Crossover above Room Temperature and Magnetic Coupling in Trinuclear Transition‐Metal Complexes with Anionic 1,2,4‐Triazole Ligands

Hysteretic Spin Crossover above Room Temperature and Magnetic Coupling in Trinuclear Transition‐Metal Complexes with Anionic 1,2,4‐Triazole Ligands

A ferrocenyl-substituted 1,2,4-triazole ligand and its FeII, NiII and CuII 1D-chain complexes

Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds

Contact Info

Product

Resources

About