Structural and Kinetic Studies of Spin Crossover in an Iron(II) Complex with a Novel Tripodal Ligand

1996 ◽  
Vol 35 (17) ◽  
pp. 5055-5060 ◽  
Author(s):  
Ala H. R. Al-Obaidi ◽  
Kenneth B. Jensen ◽  
John J. McGarvey ◽  
Hans Toftlund ◽  
Bent Jensen ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Kinetic Studies ◽  
Tripodal Ligand

scholarly journals Solvent-Induced Hysteresis Loop in Anionic Spin Crossover (SCO) Isomorph Complexes

2021 ◽  
Vol 7 (6) ◽  
pp. 75
Author(s):  
Emmelyne Cuza ◽  
Samia Benmansour ◽  
Nathalie Cosquer ◽  
Françoise Conan ◽  
Carlos J. Gómez-García ◽  
...  
Keyword(s):  
Metal Ion ◽  
Spin Crossover ◽  
Magnetic Behaviour ◽  
Magnetic Studies ◽  
Tridentate Ligands ◽  
Tripodal Ligand ◽  
Single Crystal Structures ◽  
One Step ◽  
Lower Temperature ◽  
Step Transition

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.

A Tripodal Ligand Containing Three Imidazole Groups Inducing Spin Crossover in Both Fe(II) and Fe(III) Complexes; Structures and Spin Crossover Behaviors of the Complexes

2004 ◽  
Vol 33 (3) ◽  
pp. 350-351 ◽  
Author(s):  
Hiromi Ohta ◽  
Yukinari Sunatsuki ◽  
Masaaki Kojima ◽  
Seiichiro Iijima ◽  
Haruo Akashi ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Tripodal Ligand

scholarly journals Solvent-Induced Hysteresis Loop in Anionic Spin Crossover (SCO) Isomorph Complexes

2021 ◽  
Author(s):  
Emmelyne Cuza ◽  
Samia Benmansour ◽  
Nathalie Cosquer ◽  
Francoise Conan ◽  
Carlos J. Gómez-García ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Magnetic Studies ◽  
Tridentate Ligands ◽  
Tripodal Ligand ◽  
X Ray ◽  
Mononuclear Complexes ◽  
One Step ◽  
Step Transition ◽  
Heating Up ◽  
Crystal Characterizations

Reactions of Fe(II) with the tris-(pyridin-2-yl)ethoxymethane (py3C-OEt) tripodal ligand in presence of the pseudohalide ancillary NCE- (E = S, Se, BH3) ligands led to a series of three mononuclear complexes formulated as [Fe(py3C-OEt)2][Fe(py3C-OEt)(NCE)3]2·2CH3CN, with E = S (1), BH3 (2) and Se (3). Single crystal characterizations (complexes 1-2) and X-ray powder diffraction (complexes 1-3) reveal monomeric isomorph structures formed by the spin crossover (SCO) anionic [Fe(py3C-OEt)(NCE)3] complex, associated with the low spin (LS) cationic [Fe(py3C-OEt)2]2+ complex and two solvent acetonitrile molecules. In the [Fe(py3C-OEt)2]2+ cation, the Fe(II) is coordinated by two py3C-OEt tridentate ligands, while the [Fe(py3C-OEt)(NCE)3] anion displays a hexacoordinated environment involving three N-donor atoms of one py3C-OEt ligand and three nitrogen atoms arising from of the three (NCE) coligands. The magnetic studies show the presence of gradual SCO behavior for the three complexes: a one-step transition around 205 K for 1 and two step-transitions for compounds 2 and 3, centred at 245 K and 380 K for 2, and at 170 K and 298 K for 3. The magnetic behaviors of complexes 1 and 2 remain unchanged when heating up to 500 K, while complex 3 shows significant changes which are caused by the crystallisation solvent loss above room temperature.

Thermal and Pressure Induced Spin Crossover of a Novel Iron(III) Complex with a Tripodal Ligand Involving Three Imidazole Groups

2001 ◽  
Vol 30 (12) ◽  
pp. 1254-1255 ◽  
Author(s):  
Yukinari Sunatsuki ◽  
Masafumi Sakata ◽  
Susumu Matsuzaki ◽  
Naohide Matsumoto ◽  
Masaaki Kojima
Keyword(s):  
Spin Crossover ◽  
Tripodal Ligand

Spin Crossover in Fe(II) and Co(II) Complexes with the Same Click-Derived Tripodal Ligand

2014 ◽  
Vol 53 (16) ◽  
pp. 8203-8212 ◽  
Author(s):  
David Schweinfurth ◽  
Serhiy Demeshko ◽  
Stephan Hohloch ◽  
Marc Steinmetz ◽  
Jan Gerit Brandenburg ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Tripodal Ligand

Spin-crossover in an iron(iii) complex showing a broad thermal hysteresis

2021 ◽  
Author(s):  
Cyril Rajnák ◽  
Romana Mičová ◽  
Ján Moncoľ ◽  
Ľubor Dlháň ◽  
Christoph Krüger ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Mononuclear Complex ◽  
Hysteresis Width ◽  
Thermally Induced

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).

Flavin radicals, conformational sampling and robust design principles in interprotein electron transfer: the trimethylamine dehydrogenase-electron-transferring flavoprotein complex

2004 ◽  
Vol 71 ◽  
pp. 1-14
Author(s):  
David Leys ◽  
Jaswir Basran ◽  
François Talfournier ◽  
Kamaldeep K. Chohan ◽  
Andrew W. Munro ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Kinetic Studies ◽  
Molecular Assembly ◽  
Conformational Sampling ◽  
Trimethylamine Dehydrogenase ◽  
Key Residues ◽  
Electron Transferring Flavoprotein ◽  
Electron Transfer Complex

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.

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