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Cooperative Iron(II) Spin Crossover Complexes with N₄O₂ Coordination Sphere

Title data

Weber, Birgit ; Kaps, Eike ; Weigand, Jan ; Carbonera, Chiara ; Létard, Jean-François ; Achterhold, Klaus ; Parak, Fritz G.:
Cooperative Iron(II) Spin Crossover Complexes with N₄O₂ Coordination Sphere.
In: Inorganic Chemistry. Vol. 47 (2008) Issue 2 . - pp. 487-496.
ISSN 1520-510X
DOI: https://doi.org/10.1021/ic070067o

Abstract in another language

Two new spin crossover complexes [FeL(py)2] (1) and [FeL(DMAP)2] (2) with L being a tetradentate N2O22- coordinating Schiff-base-like ligand [([3,3‘]-[1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentanedionato)(2-)-N,N‘,O2,O2‘], py = pyridine and DMAP = p-dimethylaminopyridine have been investigated using temperature-dependent susceptibility and thermogravimetric and photomagnetic measurements as well as Mössbauer spectroscopy and X-ray structure analysis. Both complexes show a cooperative spin transition with an approximately 9 K wide thermal hysteresis loop in the case of 2 (T1/2↑ = 183 K and T1/2↓ = 174 K) and an approximately 2 K wide thermal hysteresis loop in the case of the pyridine diadduct 1 (T1/2↑ = 191 K and T1/2↓ = 189 K). The spin transition was additionally followed by different temperature-scanning calorimetry and Mössbauer spectroscopy for 2, and a good agreement for the transition temperatures obtained with the different methods was found. Results from X-ray structure analysis indicate that the cooperative interactions are due to elastic interactions in both compounds. They are more pronounced in the case of 2 with very short intermolecular iron−iron distances of 7.2 Å and several intense C−C contacts. The change of the spin state at the iron center is accompanied by a change of the O−Fe−O angle, the so-called bit of the equatorial ligand, from 108° in the high-spin state to 90° in the low-spin state. The reflectivity measurements of both compounds give at low temperature indication that at the sample surface the light-induced excited spin state trapping (LIESST) effect occurs. In bulk condition using a SQUID magnetometer the complex 2 displays some photomagnetic properties with an photoexcitation level of 60% and a T(LIESST) value of 53 K.

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: 27 Jul 2017 13:19
Last Modified: 27 Jul 2017 13:19
URI: https://eref.uni-bayreuth.de/id/eprint/38855