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Crystal structure and spin crossover studies on bis(2,6-bis(benzimidazol-2-yl)pyridine) iron(II) perchlorate |
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| Authors: | Roman Bo?a ,Peter Baran,L'ubor Dlhá ň,Hartmut Fuess,Wolfgang Haase,Franz Renz,Wolfgang Linert,Ingrid Svoboda,Rü diger Werner |
| Affiliation: | a Department of Inorganic Chemistry, Slovak Technical University, SK-812 37, Bratislava, Slovakia b Institute of Physical Chemistry, Institute of Material Science, Technical University Darmstadt, D-64289, Darmstadt, Germany c Institute of Inorganic Chemistry, Technical University Vienna, A-1060, Vienna, Austria |
| Abstract: | The structure of the [Fe(bzimpy)2](ClO4)2·xH2O system (x = 0.25) was determined by single crystal X-ray structure analysis. The Fe(II) ion is hexacoordinated by six donor nitrogen atoms. The magnetic properties of the complex were investigated by powder magnetic susceptibility measurements and ESR. The freshly prepared sample does not show any traces of iron(III) impurities but these are formed as a function of time. After 1 year the sample contains 8.2% iron(III) as shown by UV spectroscopy and indicated by geff = 4.3 and 2.0 in its ESR spectrum. This explains the recorded ξ versus T behaviour at low temperature: with increasing temperature the ξ value decreases according to the Curie-Weiss law for a S = 5/2 system having an effective g = 4.3. Above 220 K a continuous increase in the ξ value is observed and a spin crossover applies. The spin transition is not complete at room temperature. A pronounced hysteresis is observed upon heating/cooling the sample between 220 and 414 K on the basis of magnetic data and infrared spectra. |
| Keywords: | Crystal structure MMagnetism Iron(II) complexes Spin crossover Hysteresis |
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