[Zurück]

P. Weinberger, J. Schweifer, K. Mereiter, M. Boca, G. Wiesinger, W. Linert:
"Temperature-dependent far FT-IR spectroscopy of spin-crossover complexes";
Poster: XXV European Congress on Molecular Spectroscopy (EUCMOS XXV), Coimbra, Portugal; 27.08.2000 - 01.09.2000; in: "Book of Abstracts", (2000), S. 298.

In analogy to a common synthesis of N-substituted 5-H tetrazoles, the new bidentate ligand 1,1´-(1,2-ethanediyl)bis-5H-tetrazole [endi] was synthesized, and characterised by X-ray diffraction, NMR, FT-IR, and UV-VIS spectroscopy. By using iron(II) bis-tetrafluoroborate hexahydrate the complexation yields a 1-dimensionallinear coordination polymer exhibiting a temperature depending spin crossover phenomenon. The thermally induced spin state switching of the iron(II) coordination center changes the energy of the d-d transition, which can be observed as a temperture dependent color change of the complex being monitored in the UV-VIS. Even more sensitive to the change of the spin state is the iron-nitrogen bond. The stretching vibration of the iron-nitrogen bond in the high spin complex is observed at 300 cm^-1, whereas the corresponding low spin complex features two absorptions at 400 cm^-1 and 430 cm^-1. The temperature dependent data derived from far FTIR spectroscopic measurements are in good agreement with results, which were independently determined by temperature dependent ⁵⁷Fe-Mössbauer spectroscopy and temperature dependent magnetic susceptibility measurements.