Towards direct correlations between spin-crossover and structural features in iron(II) complexes

2003 ◽  
Vol 59 (4) ◽  
pp. 479-486 ◽  
Author(s):  
Mathieu Marchivie ◽  
Philippe Guionneau ◽  
Jean-François Létard ◽  
Daniel Chasseau
Keyword(s):  
Crystal Structures ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition ◽  
Intermolecular Hydrogen Bond ◽  
Structural Features ◽  
Gradual Transition ◽  
Hydrogen Bond Interaction ◽  
First Approximation ◽  
Two Phases

The [Fe(PM-BiA)2(NCS)2] complex, where PM is N-2-pyridylmethylene and BiA is 4-aminobiphenyl, crystallizes in two polymorphs. The two phases, denoted (I) and (II), undergo a spin-crossover when the sample is cooled and present distinct spin-transition features as (I) shows a very abrupt spin transition, while (II) exhibits a gradual transition. The two forms of the complex are used to investigate the correlations that exist between the spin-transition features and structural features. This article presents the crystal structures of polymorph (II) at room temperature (high spin) and at 120 K (low spin), including a comparison with those of polymorph (I). This study reveals that the packing, in a first approximation, is similar in both forms. In order to look at the crystal structures in more detail, a new angular parameter, denoted θNCS, as well as a particular type of intermolecular hydrogen-bond interaction, which involves the S atoms of the NCS ligands, are investigated. Interestingly, this angle and this intermolecular interaction can be directly connected to the cooperativity of the spin transition. Such a result is extended to all the SCO iron(II) complexes belonging to the same family of the general formula [Fe(PM-L)2(NCS)2].

One Shot Laser Pulse Induced Reversible Spin Transition in the Spin-Crossover Complex [Fe(C4H4N2){Pt(CN)4}] at Room Temperature

2005 ◽  
Vol 117 (26) ◽  
pp. 4137-4141 ◽  
Author(s):  
Sébastien Bonhommeau ◽  
Gábor Molnár ◽  
Ana Galet ◽  
Antoine Zwick ◽  
José-Antonio Real ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition

Amphiphilic iron(ii) spin crossover coordination polymers: crystal structures and phase transition properties

2019 ◽  
Vol 7 (5) ◽  
pp. 1151-1163 ◽  
Author(s):  
Johannes Weihermüller ◽  
Stephan Schlamp ◽  
Wolfgang Milius ◽  
Florian Puchtler ◽  
Josef Breu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Crystal Structures ◽  
Coordination Polymers ◽  
Spin Crossover ◽  
Spin Transition ◽  
Spin Crossover Complexes ◽  
Platelet Formation

A cooperative spin transition and thin platelet formation is observed for 1D coordination polymers of amphiphilic iron(ii) spin crossover complexes.

scholarly journals Iron(III) Azadiphenolate Compounds in a New Family of Spin Crossover Iron(II)–Iron(III) Mixed-Valent Complexes

2019 ◽  
Vol 5 (2) ◽  
pp. 37 ◽  
Author(s):  
Wasinee Phonsri ◽  
David S. Macedo ◽  
Barnaby A. I. Lewis ◽  
Declan F. Wain ◽  
Keith S. Murray
Keyword(s):  
Crystal Structures ◽  
Spin Crossover ◽  
Crystal Packing ◽  
Spin Transition ◽  
Double Salt ◽  
Magnetic Studies ◽  
Cationic Precursor ◽  
New Family ◽  
Double Spin ◽  
Crystal Design

A new family of mixed valent, double salt spin crossover compounds containing anionic FeIII and cationic FeII compounds i.e., [FeII{(pz)3CH}2][FeIII(azp)2]2·2H2O (4), [FeII(TPPZ)2][FeIII(azp)2]2]·H2O (5) and [FeII(TPPZ)2][FeIII(azp)2]2]·H2O·3MeCN (6) (where (pz)3CH = tris-pyrazolylmethane, TPPZ = 2,3,5,6, tetrapyridylpyrazine and azp2− = azadiphenolato) has been synthesized and characterised. This is the first time that the rare anionic spin crossover species, [FeIII(azp)2]−, has been used as an anionic component in double salts complexes. Single crystal structures and magnetic studies showed that compound 6 exhibits a spin transition relating to one of the FeIII centres of the constituent FeII and FeIII sites. Crystal structures of the anionic and cationic precursor complexes were also analysed and compared to the double salt products thus providing a clearer picture for future crystal design in double spin crossover materials. We discuss the effects that the solvent and counterion had on the crystal packing and spin crossover properties.

Titelbild: One Shot Laser Pulse Induced Reversible Spin Transition in the Spin-Crossover Complex [Fe(C4H4N2){Pt(CN)4}] at Room Temperature (Angew. Chem. 26/2005)

2005 ◽  
Vol 117 (26) ◽  
pp. 4011-4011 ◽  
Author(s):  
Sébastien Bonhommeau ◽  
Gábor Molnár ◽  
Ana Galet ◽  
Antoine Zwick ◽  
José-Antonio Real ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition

One Shot Laser Pulse Induced Reversible Spin Transition in the Spin-Crossover Complex [Fe(C4H4N2){Pt(CN)4}] at Room Temperature

2005 ◽  
Vol 44 (26) ◽  
pp. 4069-4073 ◽  
Author(s):  
Sébastien Bonhommeau ◽  
Gábor Molnár ◽  
Ana Galet ◽  
Antoine Zwick ◽  
José-Antonio Real ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition

scholarly journals Five 2,6-Di(pyrazol-1-yl)pyridine-4-carboxylate Esters, and the Spin States of their Iron(II) Complexes

2019 ◽  
Vol 5 (1) ◽  
pp. 9 ◽  
Author(s):  
Iurii Galadzhun ◽  
Rafal Kulmaczewski ◽  
and Malcolm A. Halcrow
Keyword(s):  
Room Temperature ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Benzyl Ester ◽  
The Other ◽  
Spin States ◽  
Phenyl Ester ◽  
Coupling Reagent ◽  
Complex Salts

Two phenyl ester and three benzyl ester derivatives have been synthesized from 2,6-di(pyrazol-1-yl)pyridine-4-carboxylic acid and the appropriate phenyl or benzyl alcohol using N,N’-dicyclohexylcarbodiimide as the coupling reagent. Complexation of the ligands with Fe[BF4]2·6H2O in acetone yielded the corresponding [FeL2][BF4]2 complex salts. Four of the new ligands and four of the complexes have been crystallographically characterised. Particularly noteworthy are two polymorphs of [Fe(L3)2][BF4]2·2MeNO2 (L3 = 3,4-dimethoxyphenyl 2,6-di{pyrazol-1-yl}pyridine-4-carboxylate), one of which is crystallographically characterised as high-spin while the other exhibits the onset of spin-crossover above room temperature. The other complexes are similarly low-spin at low temperature but exhibit gradual spin-crossover on heating, except for an acetone solvate of [Fe(L5)2][BF4]2 (L5 = benzyl 2,6-di{pyrazol-1-yl}pyridine-4-carboxylate), which exhibits a more abrupt spin-transition at T½ = 273 K with 9 K thermal hysteresis.

Two New Iron(II) Spin-Crossover Complexes with N4O2Coordination Sphere and Spin Transition around Room Temperature

2009 ◽  
Vol 2009 (36) ◽  
pp. 5527-5534 ◽  
Author(s):  
Birgit Weber ◽  
Jaroslava Obel ◽  
Dunie Henner-Vásquez ◽  
Wolfgang Bauer
Keyword(s):  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition ◽  
Spin Crossover Complexes

scholarly journals High-temperature Spin Crossover of a Solvent-Free Iron(II) Complex with the Linear Hexadentate Ligand [Fe(L2-3-2Ph)](AsF6)2 (L2-3-2Ph = bis[N-(1-Phenyl-1H-1,2,3-triazol-4-yl)methylidene-2-aminoethyl]-1,3- propanediamine)

2019 ◽  
Vol 5 (1) ◽  
pp. 10 ◽  
Author(s):  
Hiroaki Hagiwara
Keyword(s):  
Room Temperature ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spin Transition ◽  
Three Dimensional ◽  
Solvent Free ◽  
Supramolecular Network ◽  
Scanning Calorimetry ◽  
Mononuclear Iron ◽  
3D Network

A novel mononuclear iron(II) complex with a linear hexadentate N6 ligand, containing two 1,2,3-triazole moieties, [Fe(L2-3-2Ph)](AsF6)2 (1), was synthesized (L2-3-2Ph = bis[N-(1-Phenyl-1H-1,2,3-triazol-4-yl)methylidene-2-aminoethyl]-1,3-propanediamine). Variable-temperature magnetic susceptibility measurements revealed a gradual one-step spin crossover (SCO) between the high-spin (HS, S = 2) and low-spin (LS, S = 0) states above room temperature (T1/2 = 468 K). The spin transition was further confirmed by differential scanning calorimetry (DSC). A single-crystal X-ray diffraction study showed that the complex was in the LS state (S = 0) at room temperature (296 K). In the crystal lattice, a three-dimensional (3D) supramolecular network was formed by intermolecular CH⋯ and – interactions of neighboring complex cations [Fe(L2-3-2Ph)]2+. AsF6− ions were located interstitially in the 3D network of complex cations, with no solvent-accessible voids. The crystal structure at 448 K (mixture of HS and LS species) was also successfully determined thanks to the thermal stability of the solvent-free crystal.

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