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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.
Bd. 47
(2008)
Heft 2
.
- S. 487-496.
ISSN 1520-510X
DOI: https://doi.org/10.1021/ic070067o
Abstract
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.
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| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Institutionen der Universität: | Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Professur Anorganische Chemie IV > Professur Anorganische Chemie IV - Univ.-Prof. Dr. Birgit Weber Fakultäten Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Professur Anorganische Chemie IV |
| Titel an der UBT entstanden: | Nein |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik > 540 Chemie |
| Eingestellt am: | 27 Jul 2017 13:19 |
| Letzte Änderung: | 27 Jul 2017 13:19 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/38855 |