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Synthesis and Characterisation of Two New Iron(II) Spin-Crossover Complexes with N₄O₂ Coordination Spheres : Optimizing Preconditions for Cooperative Interactions

Title data

Weber, Birgit ; Kaps, Eike ; Desplanches, Cédric ; Létard, Jean-François ; Achterhold, Klaus ; Parak, Fritz G.:
Synthesis and Characterisation of Two New Iron(II) Spin-Crossover Complexes with N₄O₂ Coordination Spheres : Optimizing Preconditions for Cooperative Interactions.
In: European Journal of Inorganic Chemistry. Vol. 2008 (2008) Issue 31 . - pp. 4891-4898.
ISSN 1099-0682
DOI: https://doi.org/10.1002/ejic.200800420

Abstract in another language

Two new spin-crossover complexes, [FeL1(phpy)2] (1) and [FeL2(phpy)2](phpy) (2), with L1 and L2 being tetradentate N2O22–-coordinating Schiff-base-like ligands {L1 = (E,E)-[diethyl 2,2′-[1,2-phenylenebis(iminomethylidyne)]bis(3-oxobutanoato)(2–)-N,N′,O3,O3′], L2 = [(3,3′)-[1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentanedionato)(2–)-N,N′,O2,O2′]and phpy = 4-phenylpyridine} have been investigated using temperature-dependent susceptibility and photomagnetic measurements, as well as Mössbauer spectroscopy and X-ray structure analysis. Compound 1 shows a cooperative spin transition with a thermal hysteresis loop approximately 4 K wide (T1/2↓ = 232 K and T1/2↑ = 236 K). The spin transition of 2 is gradual with T1/2 ≈ 290 K. Results from X-ray structure analysis indicate that the cooperative interactions are due to elastic interactions with several intense C–C contacts in the case of 1. The change of the spin state at the iron centre is accompanied by a change of the O–Fe–O angle, the so-called bite of the equatorial ligand, from 107° in the high-spin state to 89° in the low-spin state. Reflectivity measurements of 1 indicate that the Light-Induced Excited Spin State Trapping (LIESST) effect occurs at the sample surface at low temperatures. In the bulk solid, photomagnetic properties with a photoexcitation level of 30 % and a T(LIESST) value of 41 K are observed using a SQUID magnetometer.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry IV > Chair Anorganic Chemistry IV - Univ.-Prof. Dr. Birgit Weber
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry IV
Result of work at the UBT: No
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 28 Jul 2017 09:09
Last Modified: 28 Jul 2017 09:09
URI: https://eref.uni-bayreuth.de/id/eprint/38856