Spin-crossover thermal hysteresis and light-induced effect on iron(II) complexes with tripodal tris(2-pyridyl)methanol

Yamasaki, Masaru; Ishida, Takayuki

doi:10.1016/j.poly.2014.10.013

Cited by 19 publications

(36 citation statements)

References 34 publications

(19 reference statements)

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“…The crystal involves two molar methanol molecules; namely, the composition formula is [Fe(CH 3 S-pybox) 2 ](ClO 4 ) 2 (CH 3 OH) 2 , being consistent with the results of the elemental analysis and magnetic measurements (see below). From the Fe-N bond lengths (Table 2), the state is suggested to be LS at 100 K. The molecular structure ( Figure 1d) displays a relatively linear N(py)-Fe-N(py) axis (176.62 (19) • ), as usually found in the LS molecules of this family. At high temperatures (e.g., 400 K), the crystals were broken down and the crystal structure analysis was unsuccessful.…”

Section: Crystal Structuresmentioning

confidence: 64%

“…Iron(II) (3d 6 ) coordination compounds attract a great deal of attention in various SCO complexes, because SCO takes place between dia-and paramagnetic states to show drastic change in magnetic and chromic properties. The six-nitrogen donor structures (i.e., Fe II N 6 ) have been studied extensively, and in particular diimines like 2-pyridylmethyleneimine and bipyridyl derivatives [8][9][10][11][12][13] and triimines like 2,6-bis(azaaryl)pyridine derivatives and tripodal tris(azaaryl) compounds [14][15][16][17][18][19] are the most popular ligands for this purpose. The structural similarity found between the meridional SCO ligands 1-bpp [14] and 3-bpp [15] (2,6-bis(pyrazol-1-yl)-and 2,6-bis(pyrazol-3-yl)pyridine, respectively) affords us a clue for the development of robust SCO ligands with respect to the ligand-field engineering.…”

Section: Introductionmentioning

confidence: 99%

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Pybox-Iron(II) Spin-Crossover Complexes with Substituent Effects from the 4-Position of the Pyridine Ring (Pybox = 2,6-Bis(oxazolin-2-yl)pyridine)

Kimura

Ishida

2017

Inorganics

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Spin-crossover (SCO) behavior of a series of [Fe(X-pybox) 2 ](ClO 4 ) 2 was investigated, where X-pybox stands for 4-X-substituted 2,6-bis(oxazolin-2-yl)pyridine with X = H, Cl, Ph, CH 3 O, and CH 3 S. We confirmed that the mother compound [Fe(H-pybox) 2 ](ClO 4 ) 2 underwent SCO above room temperature. After X was introduced, the SCO temperatures (T 1/2 ) were modulated as 310, 230, and 330 K for X = Cl, Ph, and CH 3 S, respectively. The CH 3 O derivative possessed the high-spin state down to 2 K. Crystallographic analysis for X = H, Cl, CH 3 O, and CH 3 S was successful, being consistent with the results of the magnetic study. Distorted coordination structures stabilize the HS (high-spin) state, and the highest degree of the coordination structure distortion is found in the CH 3 O derivative. A plot of T 1/2 against the Hammett substituent constant σ p showed a positive relation. Solution susceptometry was also performed to remove intermolecular interaction and rigid crystal lattice effects, and the T 1/2 's were determined as 260, 270, 240, 170, and 210 K for X = H, Cl, Ph, CH 3 O, and CH 3 S, respectively, in acetone. The substituent effect on T 1/2 became very distinct, and it is clarified that electron-donating groups stabilize the HS state.

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Section: Crystal Structuresmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Pybox-Iron(II) Spin-Crossover Complexes with Substituent Effects from the 4-Position of the Pyridine Ring (Pybox = 2,6-Bis(oxazolin-2-yl)pyridine)

Kimura

Ishida

2017

Inorganics

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“…While almost all the SCO materials reported up today are either cationic or neutral [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], the number of anionic complexes exhibiting the SCO phenomenon is relatively limited compared to the several hundreds of examples of neutral and cationic complexes reported every year. To the best of our knowledge, all the anionic SCO complexes are based on Fe(III) [18][19][20][21][22][23] or Fe(II) [24][25][26][27][28][29][30]. For those based on Fe(II), three different In addition to these SCO salts based on the anionic [Fe(py 3 C-R)(NCS) 3 ] − complexes (Scheme 1b), other related systems with different structural features have also been investigated.…”

Section: Introductionmentioning

confidence: 99%

Spin Cross-Over (SCO) Anionic Fe(II) Complexes Based on the Tripodal Ligand Tris(2-pyridyl)ethoxymethane

et al. 2020

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Reactions of Fe(II) with the tripodal chelating ligand 1,1,1-tris(2-pyridyl)ethoxymethane (py3C-OEt) and (NCE)− co-ligands (E = S, Se, BH3) give a series of mononuclear complexes formulated as [Fe(py3C-OEt)2][Fe(py3C-OEt)(NCE)3]2·2CH3CN, with E = S (1) and BH3 (2). These compounds are the first Fe(II) spin cross-over (SCO) complexes based on the tripodal ligand tris(2-pyridyl)ethoxymethane and on the versatile co-ligands (NCS)− and (NCBH3)−. The crystal structure reveals discrete monomeric isomorph structures formed by a cationic [Fe(py3C-OEt)2]2+ complex and by two equivalent anionic [Fe(py3C-OEt)(NCE)3]− complexes. In the cations the Fe(II) is facially coordinated by two py3C-OEt tripodal ligands whereas in the anion the three nitrogen atoms of the tripodal ligand are facially coordinated and the N-donor atoms of the three (NCE)− co-ligands occupy the remaining three positions to complete the distorted octahedral environment of the Fe(II) centre. The magnetic studies show the presence of gradual SCO for both complexes: A one-step transition around 205 K for 1 and a two-step transition for compound 2, centered around 245 K and 380 K.

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“…Spin-crossover (SCO) is a reversible transition between low-spin (LS) and high-spin (HS) states by external stimuli like heat, light, pressure, or magnetic field [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. For development of multi-functional materials involving thermo-and photo-chromisms and -magnetisms, bistability exhibiting thermal…”

Section: Introductionmentioning

confidence: 99%

Spin-Crossover Hysteresis of [FeII(LHiPr)2(NCS)2] (LHiPr = N-2-Pyridylmethylene-4-Isopropylaniline) Accompanied by Isopropyl Conformation Isomerism

Mochida¹,

Kimura²,

Ishida³

2015

Magnetochemistry

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[Fe II (LH iPr)2(NCS)2] (LH iPr = N-2-pyridylmethylene-4-isopropylaniline) showed an abrupt spin-crossover (SCO) at T1/2↓ = 154 K on cooling and at T1/2↑ = 167 K on heating. The thermal hysteresis with a width of 13 K is related with the structural solid-state phase transition. The space group was unchanged as P21/n with Z = 8, and there are two crystallographically independent molecules in a unit cell at 130 and 180 K. The two iron (II) sites synchronously underwent the SCO. The most drastic structural change across the SCO was found in the conformation isomerization of an isopropyl group. Namely, rotation around the C(sp 2)-C(sp 3) bond by ca. 120° takes place during the SCO. There is no structural disorder in the high-temperature phase. The thermal hysteresis probably originates in the bulk isomerization requiring considerable activation energy in the crystalline solid.

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Spin-crossover thermal hysteresis and light-induced effect on iron(II) complexes with tripodal tris(2-pyridyl)methanol

Cited by 19 publications

References 34 publications

Pybox-Iron(II) Spin-Crossover Complexes with Substituent Effects from the 4-Position of the Pyridine Ring (Pybox = 2,6-Bis(oxazolin-2-yl)pyridine)

Pybox-Iron(II) Spin-Crossover Complexes with Substituent Effects from the 4-Position of the Pyridine Ring (Pybox = 2,6-Bis(oxazolin-2-yl)pyridine)

Spin Cross-Over (SCO) Anionic Fe(II) Complexes Based on the Tripodal Ligand Tris(2-pyridyl)ethoxymethane

Spin-Crossover Hysteresis of [FeII(LHiPr)2(NCS)2] (LHiPr = N-2-Pyridylmethylene-4-Isopropylaniline) Accompanied by Isopropyl Conformation Isomerism

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