Heteroleptic Fe(II) Complexes with N<sub>4</sub>S<sub>2</sub> Coordination as a Platform for Designing Spin-Crossover Materials

Yergeshbayeva, Sandugash; Hrudka, Jeremy J.; Lengyel, Jeff; Еркасов, Р. Ш.; Stoian, Sebastian A.; Dragulescu‐Andrasi, Alina; Shatruk, Michael

doi:10.1021/acs.inorgchem.7b01415

Cited by 19 publications

(22 citation statements)

References 34 publications

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“…The average Fe-N bond length of 1.990 Å and Fe-S bond length of 2.264 Å in C1 (@173 K) are in accordance with those reported in literature and account for an iron(II) ion in the [LS] state [23][24][25][26][27][28][29]. Figure S7 shows the crystal structure/asymmetric unit of C1 (@173 K).…”

Section: Crystal Structuressupporting

confidence: 85%

First Cobalt(II) Spin Crossover Compound with N4S2-Donorset

et al. 2020

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Herein we report the synthesis and characterization of a novel bis-tridentate 1,3,4-thiadiazole ligand (L = 2,5-bis[(2-pyridylmethyl)thio]methyl-1,3,4-thiadiazole). Two new mononuclear complexes of the type [MII(L)2](ClO4)2 (with M = FeII (C1) and CoII (C2)) have been synthesized, containing the new ligand (L). In both complexes the metal centers are coordinated by an N4S2-donorset and each of the two ligands is donating to the metal ion with just one of the tridentate pockets. The iron(II) complex (C1) is in the low spin [LS] state below room temperature and shows an increase in the magnetic moment only above 300 K. In contrast, the cobalt(II) complex (C2) shows a gradual spin crossover (SCO) with T1/2 = 175 K. To our knowledge, this is the first cobalt(II) SCO complex with an N4S2-coordination.

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Section: Crystal Structuressupporting

confidence: 85%

First Cobalt(II) Spin Crossover Compound with N4S2-Donorset

et al. 2020

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“…The most widely studied SCO system is iron(II) complexes where the metal centre is surrounded by six nitrogen donors, however there are fewer examples of other metal centres and geometries [13–16] . In addition to the N 6 coordination sphere, recently, it has been demonstrated that N 4 S 2 systems can produce iron(II) SCO‐active complexes, with only a handful of ligands that can provide the right ligand field for SCO to occur, [17–23] Figure 1. All the S‐based ligands contain the same thioether functional group, in combination with amine, pyridine, triazole or pyrazole nitrogen donors, and some of them contain NCE (E=S, Se or BH 3 ) co‐ligands.…”

Section: Introductionmentioning

confidence: 99%

Spin Crossover vs. High‐Spin Iron(II) Complexes in N₄S₂Coordination Sphere Containing Picolyl‐Thioether Ligands and NCE (E=S, Se and BH₃) Co‐Ligands

2021

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To study the effect of the chelate ring size on the magnetic properties of thioether‐based iron(II) metal complexes, two ligands have been envisaged, synthesised and characterised. The two ligands correspond to the bidentate benzylpicolylthioether (PySBn) and tetradentate 2,3‐bis(((2‐pyridylmethyl)thio)methyl)quinoxaline (QuinoxS). Five iron(II) complexes have been synthesised, containing either two bidentate ligands or one tetradentate ligand, and two N‐bond NCE co‐ligands (E=S, Se or BH3): trans‐[FeII(PySBn)2(NCE)2] (1 a–b) and cis‐[FeII(QuinoxS)(NCE)2] (2 a–c), a for E=S, b for E=Se and c for E=BH3. The iron(II) complexes have been characterised by standard techniques, X‐ray crystallography (except for complex 1 a) and VT‐magnetic measurements in the solid state. X‐ray crystallography showed that all the complexes are isolated in the high spin (HS) state, based on the relatively long Fe−L bond lengths, Fe−N>2.0 Å and Fe−S≈2.5–2.6 Å. VT‐magnetic measurements demonstrated that complexes 1 a and 2 a‐c are stabilised in the HS‐state, showing orbital contribution to g and zero field splitting. However, complexes 1 b shows a relatively abrupt, hysteretic, and incomplete at the low‐end spin conversion, with T1/2↓=92, T1/2↑=98 K and ΔT1/2=6 K at 5 K min−1, moreover, the hysteresis loop is scan rate dependent increasing up to 11 K at 10 K min−1. An analysis of structural and electronic parameters has been performed to rationalise the differing magnetic properties of the metal complexes, such as metallacycle size, bond lengths and angles, and cis‐ vs. trans‐coordination mode. A comparison with the literature‐reported spin crossover iron(II) complexes in N4S2 coordination sphere containing NCE co‐ligands has been conducted as well, finding that, as previously reported, the Fe−N−C(E) bond angle is diagnostic for determining the spin lability of the metal complexes, and in addition we have found that the N−C(E) bond length is too useful.

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“…[41][42][43][44][45] Among them, mononuclear or dinuclear complexes based on thioether ligands, with FeN 4 S 2 coordination sphere, have been shown to exhibit original transitions such as multi-step cooperative SCO behaviour. [41][42][43][44] Concerning Fe(II) complexes with FeN 5 S coordination sphere, very few examples have been investigated, [45][46][47][48][49] and to the best of our knowledge, only one example, [{Fe(tpc-OH)(NCS)(μ-NCS)} 2 ](PrOH) 2 (2), exhibits a SCO behaviour. 45 The latter is a dinuclear SCO Fe(II) complex based on the tripodal ligand tris(2-pyridyl)methanol (see scheme 1, R = H) for which the Fe(II) ions are connected by a pair of end-to-end thiocyanato bridges (-N:S-SCN coordination mode) in a head-to-tail configuration.…”

Section: ■Introductionmentioning

confidence: 99%

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN₅S Coordination Sphere

et al. 2018

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We present here a novel example of spin crossover phenomenon on a Fe(II) one-dimensional chain with unusual NS coordination sphere. The [{Fe(tpc-OMe)(NCS)(μ-NCS)} ] (1) compound was prepared using the tridentate tpc-OMe ligand (tpc-OMe = tris(2-pyridyl)methoxymethane), FeCl·4HO, and the KSCN salt. Crystallographic investigations revealed that the Fe(II) ions are connected by a single bridging NCS ligand (μ-κN:κS-SCN coordination mode) to afford a zigzag neutral chain running along the [010] direction, in which the thiocyanato bridging groups adopt a cis head-to-tail configuration. The (NS) metal environment arises from one thiocyanato-κS and two thiocyanato-κN ligands and from three pyridine of the fac-tpc-OMe tripodal ligand. This compound presents a unique extension of Fe(II) binuclear complexes into linear chains built on similar tripodal ligands and bridging thiocyanate anions. Compound 1 shows a spin crossover (SCO) behavior which has been evidenced by magnetic, calorimetric, and structural investigations, revealing a sharp cooperative spin transition with a transition temperature of ca. 199 K. Temperature scan rate studies revealed a very narrow hysteresis loop (∼1 K wide). Photoswitching of this compound was also performed, evidencing a very fast relaxation process at low temperature. Among other factors, the linearity of the N-bound terminal thiocyanato ligand appears as the main structural characteristic at the origin of the presence of the SCO transition in compound 1 and in the two others Fe(II) previous systems involving thiocyanato-bridges and tripodal tris(2-pyridyl)methane ligands.

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Heteroleptic Fe(II) Complexes with N₄S₂ Coordination as a Platform for Designing Spin-Crossover Materials

Cited by 19 publications

References 34 publications

First Cobalt(II) Spin Crossover Compound with N4S2-Donorset

First Cobalt(II) Spin Crossover Compound with N4S2-Donorset

Spin Crossover vs. High‐Spin Iron(II) Complexes in N₄S₂Coordination Sphere Containing Picolyl‐Thioether Ligands and NCE (E=S, Se and BH₃) Co‐Ligands

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN₅S Coordination Sphere

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Heteroleptic Fe(II) Complexes with N4S2 Coordination as a Platform for Designing Spin-Crossover Materials

Cited by 19 publications

References 34 publications

First Cobalt(II) Spin Crossover Compound with N4S2-Donorset

First Cobalt(II) Spin Crossover Compound with N4S2-Donorset

Spin Crossover vs. High‐Spin Iron(II) Complexes in N4S2Coordination Sphere Containing Picolyl‐Thioether Ligands and NCE (E=S, Se and BH3) Co‐Ligands

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN5S Coordination Sphere

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Heteroleptic Fe(II) Complexes with N₄S₂ Coordination as a Platform for Designing Spin-Crossover Materials

Spin Crossover vs. High‐Spin Iron(II) Complexes in N₄S₂Coordination Sphere Containing Picolyl‐Thioether Ligands and NCE (E=S, Se and BH₃) Co‐Ligands

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN₅S Coordination Sphere