Journal of Applied Crystallography

Volume 41, Part 3 (June 2008)

short communications

 

Neutron powder diffraction studies of two spin transition Fe^II complexes under pressure

V. Legrand, F. Le Gac, P. Guionneau and J.-F. Létard

Abstract: The pressure dependences of the lattice parameters of two spin transition compounds have been derived from neutron powder diffraction measurements at ambient temperature. The study of Fe(PM-AzA)₂(NCS)₂ [PM is N-2'-pyridylmethylene and AzA is 4-(phenylazo)aniline] has been used to validate this new type of investigation of spin crossover compounds, and the study of Fe(PM-BiA)₂(NCS)₂ (BiA is 4-aminobiphenyl) has allowed the atypical spin crossover behaviour of this compound under pressure to be explained. In addition, this complex exhibits a pressure-induced structural transition with an associated symmetry change, inducing the transformation of Fe(PM-BiA)₂(NCS)₂ into a different polymorph that avoids a first-order spin transition in favour of continuous transition.

Keywords: spin crossover complexes; phase transitions; neutron diffraction; pressure effects.

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