EXAFS and thermodynamics of Fe(II) spin transition polymeric compounds

Michalowicz, Alain; Moscovici, J.; Charton, J.; Sandid, Fares; Benamrane, Fayçal; Garcia, Yann

doi:10.1107/s0909049500018057

Cited by 17 publications

(7 citation statements)

References 8 publications

(20 reference statements)

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“…A quantitative study of the temperature dependence of the Debye–Waller factors is presented in Figure 8 a and b for compounds 1 and 3 , respectively. These results confirm those already published elsewhere 23. For 1 , there is no measurable variation of the FeN Debye–Waller factor through the transition.…”

Section: Results Of Physical Studiessupporting

confidence: 93%

“…EXAFS characterization of the structure beyond the immediate neighbors was published a year later 17. The main result in this paper was the detection of an EXAFS signal at an exceptionally long distance (around 7 Å), which was positively analyzed as the signature of the double FeFe distance, only visible if the Fe II chain is aligned 21, 23, 32. For all compounds of this series, this signal was always observed in the LS state but was doubtful in the HS state.…”

Section: Discussionmentioning

confidence: 84%

“…In this work, we focus on a qualitative discussion of the FeN 6 peak and of the multiple scattering Fe–Fe–Fe signals. Full discussion of the EXAFS structure needs full multiple scattering ab initio calculations and was beyond the scope of this study, as this topic has been addressed for similar compounds 17–19, 21, 23…”

Section: Results Of Physical Studiesmentioning

confidence: 99%

“…So far, no single crystal suitable for X‐ray diffraction has been obtained. It has, however, been possible to obtain structural information from EXAFS (X‐ray absorption fine structure) at the iron K edge17–23 and WAXS (wide angle X‐ray scattering)24 spectra. The structure of these materials consists of chains in which the neighboring iron atoms are linked by triple N 1 , N 2 ‐1,2,4‐triazole bridges 17.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Nitrogen Dynamics and Reactivity of Chiral Aziridines: Generation of Configurationally Stable Aziridinyllithium Compounds

Degennaro

Mansueto

Carenza

et al. 2011

Chemistry A European J

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Diastereomeric oxazolinylaziridines (R,R)-9 and (R,S)-9 have been regioselectively lithiated at the α-position with respect to the oxazolinyl ring. The resulting aziridinyllithium compounds proved to be chemically and configurationally stable under the experimental conditions used, thus furnishing, upon trapping with electrophiles, chiral 2,2-disubstituted aziridines, in contrast to the corresponding α-lithiated oxazolinyloxiranes that have been reported to be chemically stable but configurationally unstable. This peculiar behavior of the nitrogen-bearing heterocycle has been rationalized on the basis of DFT calculations and the observed dynamics of the aziridine nitrogen atom. The DFT analysis allowed the disclosure of a solvent-dependent differing stability of diastereomeric lithiated aziridines (R,R)-9-Li and (R,S)-9-Li, suggesting η(3)-coordinated oxazolinylaziridinyllithium compounds as likely intermediates. Such intermediates could be the result of a dynamically controlled lithiation that relies on the preliminary formation of a complex between the lithiating agent and the oxazolinyl ring. According to this model, the competing complexation of the lithiating agent by the lone pair of electrons on the aziridine nitrogen would cause addition to the oxazoline C=N bond, thus ending up with the formation of oxazolidines, which are precursors of useful chiral ketoaziridines. The proposed model has been also supported by estimating the nitrogen inversion barrier by dynamic NMR spectroscopic experiments.

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Section: Results Of Physical Studiessupporting

confidence: 93%

Section: Discussionmentioning

confidence: 84%

Section: Results Of Physical Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nitrogen Dynamics and Reactivity of Chiral Aziridines: Generation of Configurationally Stable Aziridinyllithium Compounds

Degennaro

Mansueto

Carenza

et al. 2011

Chemistry A European J

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“…EXAFS yields information about very local electronic and molecular properties, such as coordination number, ligand denticity, and isomerism [104]. In addition, structures have been derived from EXAFS spectroscopy, e.g., for iron(II)-1,2,4-triazole polymeric chain compounds [105–109], which, however, is possible in some cases only by comparative studies of analogous Cu compounds.…”

Section: Reviewmentioning

confidence: 99%

Spin state switching in iron coordination compounds

Gütlich¹,

Gaspar²,

Garcia³

2013

Beilstein J. Org. Chem.

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664

608

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SummaryThe article deals with coordination compounds of iron(II) that may exhibit thermally induced spin transition, known as spin crossover, depending on the nature of the coordinating ligand sphere. Spin transition in such compounds also occurs under pressure and irradiation with light. The spin states involved have different magnetic and optical properties suitable for their detection and characterization. Spin crossover compounds, though known for more than eight decades, have become most attractive in recent years and are extensively studied by chemists and physicists. The switching properties make such materials potential candidates for practical applications in thermal and pressure sensors as well as optical devices.The article begins with a brief description of the principle of molecular spin state switching using simple concepts of ligand field theory. Conditions to be fulfilled in order to observe spin crossover will be explained and general remarks regarding the chemical nature that is important for the occurrence of spin crossover will be made. A subsequent section describes the molecular consequences of spin crossover and the variety of physical techniques usually applied for their characterization. The effects of light irradiation (LIESST) and application of pressure are subjects of two separate sections. The major part of this account concentrates on selected spin crossover compounds of iron(II), with particular emphasis on the chemical and physical influences on the spin crossover behavior. The vast variety of compounds exhibiting this fascinating switching phenomenon encompasses mono-, oligo- and polynuclear iron(II) complexes and cages, polymeric 1D, 2D and 3D systems, nanomaterials, and polyfunctional materials that combine spin crossover with another physical or chemical property.

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Rapid Cooling Experiments and Use of an Anionic Nuclear Probe to Sense the Spin Transition of the 1D Coordination Polymers [Fe(NH₂trz)₃]SnF₆⋅n H₂O (NH₂trz=4‐amino‐1,2,4‐triazole)

Garcia

Ksenofontov

Mentior

et al. 2008

Chemistry A European J

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[Fe(NH2trz)3]SnF6n x H2O (NH(2)trz=4-amino-1,2,4-triazole; n=1 (1), n=0.5 (2)) are new 1D spin-crossover coordination polymers. Compound 2 exhibits an incomplete spin transition centred at around 210 K with a thermal hysteresis loop approximately 16 K wide. The spin transition of 2 was detected by the Mössbauer resonance of the 119Sn atom in the SnF6 (2-) anion primarily on the basis of the evolution of its local distortion. Rapid-cooling 57Fe Mössbauer and superconducting quantum interference device experiments allow dramatic widening of the hysteresis width of 2 from 16 K up to 82 K and also shift the spin-transition curve into the room temperature region. This unusual behaviour of quenched samples on warming is attributed to activation of the molecular motion of the anions from a frozen distorted form towards a regular form at temperatures well above approximately 210 K. Potential applications of this new family of materials are discussed.

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EXAFS and thermodynamics of Fe(II) spin transition polymeric compounds

Cited by 17 publications

References 8 publications

Nitrogen Dynamics and Reactivity of Chiral Aziridines: Generation of Configurationally Stable Aziridinyllithium Compounds

Nitrogen Dynamics and Reactivity of Chiral Aziridines: Generation of Configurationally Stable Aziridinyllithium Compounds

Spin state switching in iron coordination compounds

Rapid Cooling Experiments and Use of an Anionic Nuclear Probe to Sense the Spin Transition of the 1D Coordination Polymers [Fe(NH₂trz)₃]SnF₆⋅n H₂O (NH₂trz=4‐amino‐1,2,4‐triazole)

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EXAFS and thermodynamics of Fe(II) spin transition polymeric compounds

Cited by 17 publications

References 8 publications

Nitrogen Dynamics and Reactivity of Chiral Aziridines: Generation of Configurationally Stable Aziridinyllithium Compounds

Nitrogen Dynamics and Reactivity of Chiral Aziridines: Generation of Configurationally Stable Aziridinyllithium Compounds

Spin state switching in iron coordination compounds

Rapid Cooling Experiments and Use of an Anionic Nuclear Probe to Sense the Spin Transition of the 1D Coordination Polymers [Fe(NH2trz)3]SnF6⋅n H2O (NH2trz=4‐amino‐1,2,4‐triazole)

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Rapid Cooling Experiments and Use of an Anionic Nuclear Probe to Sense the Spin Transition of the 1D Coordination Polymers [Fe(NH₂trz)₃]SnF₆⋅n H₂O (NH₂trz=4‐amino‐1,2,4‐triazole)