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Updated: May 26, 2025
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Magneto-Structural Correlations, Substitution Effects and Slow Relaxation of the Magnetization on Trinuclear Linear
María A Palacios1, María Mar Quesada-Moreno2, Shefa' F Alrebei1
1Departamento de Química Inorgánica, Facultad de Ciencias, Campus Fuentenueva, Universidad de Granada, 18071, Granada, Spain.
Abstract:
We report the preparation of three neutral linear trinuclear Ni(II) complexes [Ni3(LX)2] (1-3) by self-assembly of Ni(II) ions and N3O3-tripodal Schiff base ligands, LX, which were obtained by condensation between the triamine tris(methylhydrazine)phosphorylsulfide and salicylaldehyde derivatives with substituents X=H (L1) (1), Br (L2) (2) and NO2 (L3) (3) in para position to the phenoxo group. Experimental magneto-structural studies carried out on these complexes indicate that the magnetic exchange interactions between the neighboring Ni(II) ions are ferromagnetic in nature, moderate in magnitude and clearly dependent of the electronic properties of the substituent in para position. Thus, the electron-withdrawing NO2 group decreases the ferromagnetic coupling, whereas the Br substituent, with small electronic effects, does not significantly vary the exchange coupling observed for the unsubstituted complex. Theoretical calculations performed on these complexes, containing ligands with a variety of electron-donating and withdrawing groups in para position to the phenoxo group, support that the ferromagnetic coupling decreases on passing from strong electron-donating to electron-withdrawing groups. Interestingly, complexes 1-3 show weak slow relaxation of the magnetization, with relaxation times (τ) decreasing in the order: 1>2>3. These compounds represent some of the few examples of Ni(II) complexes exhibiting slow magnetic relaxation.
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