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Thermal and Photoinduced Spin Crossover in a Mononuclear Iron(II) Complex with a Bis(pyrazolyl)pyridine Type of Ligand
Author(s) -
Šalitroš Ivan,
Fuhr Olaf,
Kruk Robert,
Pavlik Ján,
Pogány Lukáš,
Schäfer Bernhard,
Tatarko Miroslav,
Boča Roman,
Linert Wolfgang,
Ruben Mario
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201201123
Subject(s) - chemistry , spin crossover , dication , crystallography , spin transition , magnetic susceptibility , spin states , excited state , ligand (biochemistry) , ion , inorganic chemistry , atomic physics , biochemistry , physics , receptor , organic chemistry
A mononuclear iron(II) compound 1 of the general formula [Fe( L ) 2 ](ClO 4 ) 2 { L = 4‐[2,6‐bis(pyrazol‐1‐yl)pyridin‐4‐yl]benzaldehyde} was prepared and structurally characterised. Single‐crystal X‐ray structure analysis revealed the presence of a complex dication [Fe( L ) 2 ] 2+ and two ClO 4 – counteranions within the unit cell. The bond lengths and angles within the coordination polyhedron FeN 6 indicate the low‐spin state of the central iron(II) metal ion at T = 180 K. Magnetic investigations elucidate spin crossover with T 1/2 = 285 K. The experimental magnetic susceptibility data could be satisfactorily fitted with the Curie law in combination with the Ising‐like model. The room‐temperature character of the spin crossover was further studied by variable‐temperature far‐IR, Vis and Mössbauer spectroscopy. Laser irradiation of 1 carried out at 10 K gives rise to a complete low‐spin to high‐spin photoconversion. A subsequent temperature‐dependent investigation revealed the existence of a photoexcited metastable HS state up to T LIESST = 70 K (LIESST = light‐induced excited‐spin‐state trapping) as well as the presence of a light‐induced thermal hysteresis loop with a width of 10 K.