Structural, magnetic and photomagnetic study of the [Fe(PM–NEA)2(NCS)2] spin crossover complex

Jean-François Letard (1) , Matthias Kollmansberger (1) , Chiara Carbonera (1) , Mathieu Marchivie (1) , Philippe Guionneau (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

The new spin-crossover compound [Fe(PM–NEA)2(NCS)2] with PM–NEA = N-(2-pyridylmethylene)-4-(naphthalene-1-ethynyl)aniline has been synthesized. The temperature dependence of χMT (χM = molar magnetic susceptibility and T = temperature) has revealed a very gradual complete spin conversion between LS (S = 0) and HS (S = 2) states with T1/2 of about 204 K. At 10 K the well-known LIESST (light-induced excited spin state trapping) effect has been observed within the SQUID cavity, by irradiating a powder sample with a Kr+ laser coupled with an optical fibre. The HS → LS relaxation after LIESST has been analyzed with a stretched exponential behaviour. This is consistent with structural analysis, since the presence of naphthalene rings induces a less compact crystal packing than in already reported [Fe(PM–L)2(NCS)2] crystal structures. In particular, the intermolecular interaction network shows a noteworthy dissymmetry on each side of the complex. Furthermore, the structure–property relationship confirms the important role of the metal coordination sphere distortion on the T1/2 value.

Mots clés: Coordination chemistry; Iron(II) metal ions; Spin crossover; X-ray diffraction; Photomagnetism; Structure–property relationship; Phase transition

Domaines: Matériaux

Jean-François Letard, Matthias Kollmansberger, Chiara Carbonera, Mathieu Marchivie, Philippe Guionneau. Structural, magnetic and photomagnetic study of the [Fe(PM–NEA)2(NCS)2] spin crossover complex. Comptes Rendus. Chimie, 2008, 11 (10), pp.1155-1165. ⟨10.1016/j.crci.2008.05.009⟩. ⟨hal-00342698⟩