Spin-crossover in the [Fe(abpt)2(NCX)2] (X=S, Se) system: structural, magnetic, calorimetric and photomagnetic studies

Moliner, Nicolás; Muñoz, M. Carmen; Letard, Sébastien; Létard, Jean‐François; Soláns, Xavier; Burriel, R.; Castro, Miguel; Kahn, Olivier; Real, José Antonio

doi:10.1016/s0020-1693(99)00128-0

Cited by 122 publications

(107 citation statements)

References 39 publications

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“…[13] L = 2,2'-bi-2-thiazoline (bt), X = S; [14] L = 4,6-bis(2',2''-pyridyl)pyrazine (dppt), X = S; [15] or L = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt), X = S, Se, [16] or tcnoet = 1,1,3,3-tetracyano-2-ethoxypropenide [17] ) and others such as…”

Section: Introductionmentioning

confidence: 99%

Structure and Electronic Configuration of an Iron(II) Complex in a LIESST State: A Pump and Probe Method

Sheu

Chen

et al. 2009

Chemistry A European J

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Two polymorphs of mononuclear six-coordinate iron(II) spin-crossover complex trans-[Fe(tzpy)(2)(NCS)(2)] (tzpy = 3-(2-pyridyl)[1,2,3]triazolo[1,5-a]pyridine) (1) were isolated and structurally characterized. According to the thermally dependent magnetic measurements, polymorph A undergoes a gradual spin transition from a paramagnetic high-spin state ((5)T(2), S = 2, HS-1) above 200 K to a diamagnetic low-spin state ((1)A(1), S = 0, LS-1) below 120 K, whereas polymorph B shows an abrupt spin transition with T(1/2) at 102 K. Molecular and crystal structures of polymorph A in the HS-1 and LS-1 states were studied at 300 and 40 K, respectively. Significant differences in Fe-N distances and coordination geometries of Fe were found between the two spin states, as expected. Light-induced excited spin state trapping (LIESST) was observed upon irradiating the crystal with 532 nm laser light at 40 K, whereupon a metastable high-spin state (HS-2) was formed; the molecular and crystal structure of this metastable state were investigated by a pump and probe method because of its relatively fast relaxation. The electronic configuration of the Fe center in the HS-1, LS-1, and LIESST (HS-2) states were further confirmed by Fe K- and L-edge absorption spectroscopy. In addition, the C[triple bond]N stretching frequency on the ligand can also be followed through the spin transition. The excitation and relaxation process concerning such metastable state were followed by the C[triple bond]N stretching frequency and magnetic susceptibility measurements in the temperature ranges 15-55 K and 5-80 K, respectively. The structure and electronic configuration of the LIESST state of polymorph A were firmly established by X-ray diffraction, X-ray absorption, infrared absorption, and magnetic measurements. A single-crystal-to-single-crystal transition through irradiation was demonstrated. The changes in structure and electronic configuration as a result of the spin transition are believed to occur concurrently.

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Section: Introductionmentioning

confidence: 99%

Structure and Electronic Configuration of an Iron(II) Complex in a LIESST State: A Pump and Probe Method

Sheu

Chen

et al. 2009

Chemistry A European J

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“…Calcd for C6 H 11 N 3 (125.17 g mol −1 ): C 57.57, H 8.86, N 33.57. Found: C 57.63, H 9.12, N 33.65%.…”

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confidence: 99%

Effect of N⁴-Substituent Choice on Spin Crossover in Dinuclear Iron(II) Complexes of Bis-Terdentate 1,2,4-Triazole-Based Ligands

et al. 2013

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Seven new dinuclear iron(II) complexes of the general formula [Fe(II)2(PMRT)2](BF4)4·solvent, where PMRT is a 4-substituted-3,5-bis{[(2-pyridylmethyl)-amino]methyl}-4H-1,2,4-triazole, have been prepared in order to investigate the substituent effect on the spin crossover event. Variable temperature magnetic susceptibility and (57)Fe Mössbauer spectroscopy studies show that two of the complexes, [Fe(II)2(PMPT)2](BF4)4·H2O (N(4) substituent is pyrrolyl) and [Fe(II)2(PM(Ph)AT)2](BF4)4 (N(4) is N,N-diphenylamine), are stabilized in the [HS-HS] state between 300 and 2 K with weak antiferromagnetic interactions between the iron(II) centers. Five of the complexes showed gradual half spin crossover, from [HS-HS] to [HS-LS], with the following T(1/2) (K) values: 234 for [Fe(II)2(PMibT)2](BF4)4·3H2O (N(4) is isobutyl), 147 for [Fe(II)2(PMBzT)2](BF4)4 (N(4) is benzyl), 133 for [Fe(II)2(PM(CF3)PhT)2](BF4)4·DMF·H2O (N(4) is 3,5-bis(trifluoromethyl)phenyl), 187 for [Fe(II)2(PMPhT)2](BF4)4 (N(4) is phenyl), and 224 for [Fe(II)2(PMC16T)2](BF4)4 (N(4) is hexadecyl). Structure determinations carried out for three complexes, [Fe(II)2(PMPT)2](BF4)4·4DMF, [Fe(II)2(PMBzT)2](BF4)4·CH3CN, and [Fe(II)2(PM(Ph)AT)2](BF4)4·solvent, revealed that in all three complexes both iron(II) centers are stabilized in the high spin state at 90 K. A general and reliable 4-step route to PMRT ligands is also detailed.

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“…One may say that charge (electron) is transferred from the Fe ion to L1-L6 ions upon crossover from the LS to the HS state. This causes the Fe ion becoming more positive and six anionic L1-L6 ions [11,12]. Experimental values are shown in italic.…”

Section: Resultsmentioning

confidence: 99%

Geometric structure, electronic structure, and spin transition of several FeII spin-crossover molecules

Tuấn¹

2012

Journal of Applied Physics

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Spin-crossover in the [Fe(abpt)2(NCX)2] (X=S, Se) system: structural, magnetic, calorimetric and photomagnetic studies

Cited by 122 publications

References 39 publications

Structure and Electronic Configuration of an Iron(II) Complex in a LIESST State: A Pump and Probe Method

Structure and Electronic Configuration of an Iron(II) Complex in a LIESST State: A Pump and Probe Method

Effect of N⁴-Substituent Choice on Spin Crossover in Dinuclear Iron(II) Complexes of Bis-Terdentate 1,2,4-Triazole-Based Ligands

Geometric structure, electronic structure, and spin transition of several FeII spin-crossover molecules

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Spin-crossover in the [Fe(abpt)2(NCX)2] (X=S, Se) system: structural, magnetic, calorimetric and photomagnetic studies

Cited by 122 publications

References 39 publications

Structure and Electronic Configuration of an Iron(II) Complex in a LIESST State: A Pump and Probe Method

Structure and Electronic Configuration of an Iron(II) Complex in a LIESST State: A Pump and Probe Method

Effect of N4-Substituent Choice on Spin Crossover in Dinuclear Iron(II) Complexes of Bis-Terdentate 1,2,4-Triazole-Based Ligands

Geometric structure, electronic structure, and spin transition of several FeII spin-crossover molecules

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Effect of N⁴-Substituent Choice on Spin Crossover in Dinuclear Iron(II) Complexes of Bis-Terdentate 1,2,4-Triazole-Based Ligands