Synthesis, Structure, and Magnetic Property of a New Mononuclear Iron(II) Spin Crossover Complex with a Tripodal Ligand Containing Three 1,2,3-Triazole Groups

Reaction of Fe(II) with the tris-(pyridin-2-yl)ethoxymethane (py3C-OEt) tripodal ligand in the presence of the pseudohalide ancillary NCSe- (E = S, Se, BH3) ligand leads to the mononuclear complex [Fe(py3C-OEt)2][Fe(py3C-OEt)(NCSe)3]2·2CH3CN (3), which has been characterised as an isomorph of the two previously reported complexes, Fe(py3C-OEt)2][Fe(py3C-OEt)(NCE)3]2·2CH3CN, with E = S (1), BH3 (2). X-ray powder diffraction of the three complexes (1–3), associated with the previously reported single crystal structures of 1–2, revealed a monomeric isomorph structure for 3, formed by the spin crossover (SCO) anionic [Fe(py3C-OEt)(NCSe)3]− complex, associated with the low spin (LS) [Fe(py3C-OEt)2]2+ cationic complex and two solvent acetonitrile molecules. In the [Fe(py3C-OEt)2]2+ complex, the metal ion environment involves two py3C-OEt tridentate ligands, while the [Fe(py3C-OEt)(NCSe)3]− anion displays a hexacoordinated environment involving three N-donor atoms of one py3C-OEt ligand and three nitrogen atoms arising from the three (NCSe)− coligands. The magnetic studies for 3 performed in the temperature range 300-5-400 K, indicated the presence of a two-step SCO transition centred around 170 and 298 K, while when the sample was heated at 400 K until its complete desolvation, the magnetic behaviour of the high temperature transition (T1/2 = 298 K) shifted to a lower temperature until the two-step behaviour merged with a gradual one-step transition at ca. 216 K.

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Spin-State Ordering on One Sub-lattice of a Mononuclear Iron(III) Spin Crossover Complex Exhibiting LIESST and TIESST

Chemistry - A European Journal ◽

10.1002/chem.201400286 ◽

2014 ◽

Vol 20 (19) ◽

pp. 5613-5618 ◽

Cited By ~ 61

Author(s):

Kevin D. Murnaghan ◽

Chiara Carbonera ◽

Loic Toupet ◽

Michael Griffin ◽

Marinela M. Dîrtu ◽

...

Keyword(s):

Spin State ◽

Spin Crossover ◽

Mononuclear Iron

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Thermal and near-infrared light induced spin crossover in a mononuclear iron(ii) complex with a tetrathiafulvalene-fused dipyridophenazine ligand

Dalton Transactions ◽

10.1039/c6dt00920d ◽

2016 ◽

Vol 45 (28) ◽

pp. 11267-11271 ◽

Cited By ~ 20

Author(s):

F. Pointillart ◽

X. Liu ◽

M. Kepenekian ◽

B. Le Guennic ◽

S. Golhen ◽

...

Keyword(s):

Spin Crossover ◽

Near Infrared ◽

Spin Transition ◽

Infrared Light ◽

Near Infrared Light ◽

Mononuclear Iron

A thermal and photo-induced spin transition in a tetrathiafulvalene-based Fe(ii) complex.

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Stabilization of the Low-Spin State in a Mononuclear Iron(II) Complex and High-Temperature Cooperative Spin Crossover Mediated by Hydrogen Bonding

Chemistry - A European Journal ◽

10.1002/chem.201503119 ◽

2015 ◽

Vol 22 (1) ◽

pp. 331-339 ◽

Cited By ~ 19

Author(s):

Sipeng Zheng ◽

Niels R. M. Reintjens ◽

Maxime A. Siegler ◽

Olivier Roubeau ◽

Elisabeth Bouwman ◽

...

Keyword(s):

Hydrogen Bonding ◽

High Temperature ◽

Spin State ◽

Spin Crossover ◽

Mononuclear Iron

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Structural movies of the gradual spin-crossover in a molecular complex at various physical scales

Physical Chemistry Chemical Physics ◽

10.1039/c6cp04987g ◽

2016 ◽

Vol 18 (40) ◽

pp. 28307-28315 ◽

Cited By ~ 11

Author(s):

S. Lakhloufi ◽

M. H. Lemée-Cailleau ◽

G. Chastanet ◽

P. Rosa ◽

N. Daro ◽

...

Keyword(s):

Spin State ◽

Molecular Complex ◽

Spin Crossover ◽

Structural Determination ◽

Thermally Induced ◽

Mononuclear Iron

The thermally induced Spin-CrossOver (SCO) undergone by the mononuclear iron(ii) complex [Fe(PM-AzA)2(NCS)2] (PM = N-2′-pyridylmethylene, AzA = 4-(phenylazo)aniline) is fully pictured by a quasi-continuous structural determination all along the spin-state modification within the sample.

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Structural Evidence of Spin State Selection and Spin Crossover Behavior of Tripodal Schiff Base Complexes of tris(2-aminoethyl)amine and Related Tripodal Amines

Magnetochemistry ◽

10.3390/magnetochemistry6020028 ◽

2020 ◽

Vol 6 (2) ◽

pp. 28

Author(s):

Greg Brewer

Keyword(s):

Schiff Base ◽

Spin State ◽

Density Functional ◽

Spin Crossover ◽

Bimodal Distribution ◽

Structural Features ◽

Schiff Base Complexes ◽

Mononuclear Iron ◽

Experimental Values ◽

State Selection

A review of the tripodal Schiff base (SB) complexes of tris(2-aminoethyl)amine, Nap(CH2CH 2NH2)3 (tren), and a few closely related tripodal amines with Cr(II), Mn(III) (d4), Mn(II), Fe(III) (d5), Fe(II) (d6), and Co(II) (d7) is provided. Attention is focused on examination of key structural features, the M-Nimine, M-Namine, or M-O and M-Nap bond distances and Nimine-M-N(O) bite and C-Nap-C angles and how these values correlate with spin state selection and spin crossover (SCO) behavior. A comparison of these experimental values with density functional theory calculated values is also given. The greatest number, 132, of complexes is observed with cationic mononuclear iron(II) in a N6 donor set, Fe(II)N6. The dominance of two spin states, high spin (HS) and low spin (LS), in these systems is indicated by the bimodal distribution of histogram plots of Fe(II)-Nimine and Fe(II)-Nazole/pyridine bond distances and of Nimine–Fe(II)-Nazole/pyridine and C-Nap-C bond angles. The values of the two maxima, corresponding to LS and HS states, in each of these histograms agree closely with the theoretical values. The iron(II)-Nimine and iron(II)-Nazole/pyridine bond distances correlate well for these complexes. Examples of SCO complexes of this type are tabulated and a few of the 20 examples are discussed that exhibit interesting features. There are only a few mononuclear iron(III) cationic complexes and one is SCO. In addition, a significant number of supramolecular complexes of these ligands that exhibit SCO, intervalence, and chiral recognition are discussed. A summary is made regarding the current state of this area of research and possible new avenues to explore based on analysis of the present data.

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