Polymeric spin transition compounds: EXAFS and thermal behaviour

The structures of large thermal hysteresis Fe(II) polymeric spin transition compounds have been studied by EXAFS. The assumption that a peak at 7 Angs trom can be assigned to a multiple scattering double metal-metal distance i n an aligned polymeric structure is confirmed. For the first time, such an aligned structure was observed on High Spin (HS) compound of the family. A qualitative study of the thermal variation of this multiple scattering peak was performed. The correlation between this thermal behaviour. due to vari ations in the vibrational entropy, and the electronic structure of the meta llic ions is discussed.