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- Title
Spin Crossover and Valence Tautomerism in Neutral Homoleptic Iron Complexes of Bis(pyridylimino)isoindolines.
- Authors
Scheja, Anne; Baabe, Dirk; Menzel, Dirk; Pietzonka, Clemens; Schweyen, Peter; Bröring, Martin
- Abstract
Homoleptic iron complexes of six bis(pyridylimino)isoindoline (bpi) ligands with different substituents (H, Me, Et, tBu, OMe, NMe2) at the 4-positions of the pyridine moieties have been prepared and studied with regard to temperature-dependent spin and redox states by a combination of 57Fe Mössbauer spectroscopy, SQUID magnetometry, single-crystal X-ray diffraction analysis, X-band EPR, and 1H NMR spectroscopy. While the H-, methyl-, and ethyl-substituted complexes remain in a pure high-spin state irrespective of the temperature, the 4- tert-butyl-substituted derivative shows spin-crossover behavior. The methoxy- and dimethylamino-substituted compounds were found to easily undergo oxidation. In the crystalline state, valence tautomeric behavior was observed for the methoxy derivative as a thermally activated charge-transfer transition, accompanied by a spin crossover above 200 K. The valence tautomerism leads to a chelate with one of the bpi ligands as a dianion radical L2−. and with an effective spin of S=2.
- Subjects
INDOLINE; IRON compounds; SPIN crossover; VALENCE (Chemistry); TAUTOMERISM; HOMOLEPTIC compounds; PYRIDYL compounds; IMINO compounds
- Publication
Chemistry - A European Journal, 2015, Vol 21, Issue 40, p14196
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201501551