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Dynamic spin interchange in a tridentate Fe(III) Schiff-base compound

Authors: Vicente, AI; Joseph, A; Ferreira, LP; Carvalho, MD; Rodrigues, VHN; Duttine, M ; Diogo, H

Ref.: CHEMICAL SCIENCE 7(7), 4251-4258 (2016)

Abstract: The thermosalient effect is still a rare and poorly understood phenomenon, where crystals suddenly jump, bend, twist or explode upon undergoing a thermally activated phase transition. The synthesis and characterisation of the new spin transition Fe(III) compound [Fe( 5-Br-salEen)(2)][ClO4] (salEen = N-ethyl-N-(2-aminoethyl)salicylaldiminate) is described and its thermosalient behaviour reported. It is the first example of a thermosalient effect with a spin transition and magnetic, calorimetric, diffraction, microscopy and computational studies are used to characterise these effects. Both thermosalient effect and spin transition occur around 320 K upon heating and are accompanied by an anisotropic unit cell change with conservation of crystal symmetry that causes a large enough stress of the crystal lattice to induce crystal explosion. This stress can ultimately be traced back to a diffusionless and distortive structural perturbation resulting in a coupled spin transition-thermosalient effect.

DOI: 10.1039/c5sc04577k