FeIII Spin-Crossover Complexes with Photoisomerizable Ligands: Experimental and Theoretical Studies on the Ligand-Driven Light-Induced Spin Change Effect

Bannwarth, A., Schmidt, S. O., Peters, G., Sönnichsen, F. D., Thimm, W., Herges, R. and Tuczek, F. (2012) FeIII Spin-Crossover Complexes with Photoisomerizable Ligands: Experimental and Theoretical Studies on the Ligand-Driven Light-Induced Spin Change Effect European Journal of Inorganic Chemistry (16). pp. 2776-2783.

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Abstract

Conflicting results have been reported with respect to the photoinduced switching of the magnetic properties of [FeIII(salten)]+ complexes [salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate)] coordinated by photoisomerizable ligands. In order to address this problem, two FeIII complexes [Fe(salten)(3-azpy)]BPh4 (1) and [Fe(salten)(4-azpy)]BPh4 (2) have been synthesized and characterized by various physicochemical methods (azpy = phenylazopyridine). Both 1 and 2 exhibit a low spin (S = 1/2) to high spin (HS, S = 5/2) transition in the solid state. In solution at room temperature both complexes are predominantly HS. Upon exposure to 310 (trans ? cis) and 440 nm radiation (cis ? trans) the free and coordinated 3- and 4-azpy ligands undergo a reversible cistrans isomerization. For 2 a corresponding reduction of the HS fraction 2?% is observed, whereas in 1 no effect is observed. Extensive DFT calculations, which employ different functionals and basis sets, explain this experimental result. The consequences of these findings with respect to the design of spin-switchable iron(III) complexes with photoactive ligands are discussed.

Document Type: Article
Additional Information: Univ Kiel, Inst Anorgan Chem, D-24098 Kiel, Germany. Univ Kiel, Otto Diels Inst Organ Chem, D-24098 Kiel, Germany. Tuczek, F (reprint author), Univ Kiel, Inst Anorgan Chem, Max Eyth Str 2, D-24098 Kiel, Germany. ftuczek@ac.uni-kiel.de
Keywords: Spin crossover Photoswitching Density functional calculations Iron Moessbauer spectroscopy LD-LISC magnetic-properties iron(iii) complexes density functionals room-temperature structural differences correlation-energy 1st evidence molecules states approximation
ISSN: 1434-1948
Date Deposited: 14 May 2014 10:14
Last Modified: 29 Jul 2014 08:57
URI: http://eprints.uni-kiel.de/id/eprint/23815

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