Giant Ising-type Magnetic Anisotropy in Trigonal Bipyramidal Ni(II) Complexes : Experiment and Theory.

Renaud Ruamps (1) , Rémi Maurice (1) , L.J. Batchelor , Martial Boggio-Pasqua (2) , Régis Guillot , Anne-Laure Barra (3) , J. Liu , E.E. Bendeif (4) , Sébastien Pillet (4) , S. Hill , Talal Mallah (5) , Nathalie Guihéry (1)

1 SEM - Systèmes étendus et magnétisme (LCPQ)
2 PTC - Photochimie théorique et computationnelle (LCPQ)
3 LNCMI-G - Laboratoire national des champs magnétiques intenses - Grenoble
4 CRM2 - Cristallographie, Résonance Magnétique et Modélisations
5 LCI - Laboratoire de chimie inorganique

This paper reports the experimental and theoretical investigations of two trigonal bipyramidal Ni(II) complexes, [Ni(Me6tren)Cl](ClO4) (1) and [Ni(Me6tren)Br](Br) (2). High-field, high-frequency electron paramagnetic resonance spectroscopy performed on a single crystal of 1 shows a giant uniaxial magnetic anisotropy with an experimental Dexpt value (energy difference between the Ms = ± 1 and Ms = 0 components of the ground spin state S = 1) estimated to be between −120 and −180 cm-1. The theoretical study shows that, for an ideally trigonal Ni(II) complex, the orbital degeneracy leads to a first-order spin-orbit coupling that results in a splitting of the Ms = ± 1 and Ms = 0 components of approximately −600 cm-1. Despite the Jahn-Teller distortion that removes the ground term degeneracy and reduces the effects of the first-order spin-orbit interaction, the D value remains very large. A good agreement between theoretical and experimental results (theoretical Dtheor between −100 and −200 cm-1) is obtained.

Domaines: Agrégats Moléculaires et Atomiques [physics.atm-clus]; Chimie-Physique [physics.chem-ph]

Renaud Ruamps, Rémi Maurice, L.J. Batchelor, Martial Boggio-Pasqua, Régis Guillot, et al.. Giant Ising-type Magnetic Anisotropy in Trigonal Bipyramidal Ni(II) Complexes : Experiment and Theory.. Journal of the American Chemical Society, 2013, 135 (8), pp.3017-3026. ⟨10.1021/ja308146e⟩. ⟨hal-00795681⟩