Pressure-induced switching properties of the iron(III) spin-transition complex [FeIII(3-OMeSalEen)2]PF6

J. Laisney (1) , H. J Shepherd (2) , L. Rechignat (3) , Gábor Molnár (3) , E. Rivière (1) , M.-L. Boillot (1)

1 ICMMO - Institut de Chimie Moléculaire et des Matériaux d'Orsay
2 School of Physical Sciences [Canterbury]
3 LCC - Laboratoire de chimie de coordination

We investigated the effect of an externally applied pressure on the iron(III) Schiff-base compound [Fe(3-OMeSalEen)2]PF6 (H-3-OMeSalEen, condensation product of 3-methoxy-substituted salicylaldehyde and N-ethylethylenediamine), which at ambient pressure displays a thermal spin transition with a 3 K wide hysteresis loop centered at 164 K. Raman spectrometry revealed the occurrence of a complete spin-state switching process for a pressure of P1/2 = 8–9 kbar at room temperature. The evolution of lattice parameters as a function of pressure was followed by X-ray diffraction measurements on single crystals, highlighting the important microscopic aspects at the origin of the pressure-induced transition, i.e. an anisotropic response and a high compressibility of the HS molecular lattice. Variable temperature magnetic susceptibility measurements at different applied pressures revealed the smoothening of the spin transition curves and a linear increase of the transition temperatures by ca. 16.4 (1.0) K kbar−1, in good agreement with the Clausius–Clapeyron law. The non-negligible influence of the pressure transmitting oils on the intrinsic transition properties was also evidenced and attributed to mechanical interactions between the particles and the solidified matrix.

Domaines: Chimie de coordination; Chimie inorganique; Matériaux

J. Laisney, H. J Shepherd, L. Rechignat, Gábor Molnár, E. Rivière, et al.. Pressure-induced switching properties of the iron(III) spin-transition complex [FeIII(3-OMeSalEen)2]PF6. Physical Chemistry Chemical Physics, 2018, 20 (23), pp.15951-15959. ⟨10.1039/c8cp02376j⟩. ⟨hal-03325449⟩