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Analysis of the Magnetic Coupling in a Mn(II)‐U(V)‐Mn(II) Single Molecule Magnet
Author(s) -
Dey Sourav,
Rajaraman Gopalan,
Bolvin Hélène
Publication year - 2022
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202201883
Subject(s) - ferromagnetism , magnetization , chemistry , magnetic moment , ab initio , ab initio quantum chemistry methods , magnetic anisotropy , condensed matter physics , single molecule magnet , density functional theory , spin polarization , molecule , crystallography , computational chemistry , magnetic field , physics , electron , quantum mechanics , organic chemistry
[{Mn(TPA)I}{UO2(Mesaldien)}{Mn(TPA)I}]I formula (here TPA=tris(2‐pyridylmethyl)amine and Mesaldien=N,N’‐(2‐aminomethyl)diethylenebis(salicylidene imine)) reported by Mazzanti and coworkers (Chatelain et al. Angew. Chem. Int. Ed. 2014 , 53 , 13434) is so far the best Single Molecule Magnet (SMM) in the {3d–5f} class of molecules exhibiting barrier height of magnetization reversal as high as 81.0 K. In this work, we have employed a combination of ab initio CAS and DFT methods to fully characterize this compound and to extract the relevant spin Hamiltonian parameters. We show that the signs of the magnetic coupling and of the g‐factors of the monomers are interconnected. The central magnetic unit [U V O 2 ] + is described by a Kramers Doublet (KD) with negative g‐factors, due to a large orbital contribution. The magnetic coupling for the {Mn(II)‐U(V)} pair is modeled by an anisotropic exchange Hamiltonian: all components are ferromagnetic in terms of spin moments, the parallel component J Z twice larger as the perpendicular one J ⊥ . The spin density distribution suggests that spin polarization on the U(V) center favors the ferromagnetic coupling. Further, the J Z /J ⊥ ratio, which is related to the barrier height, was found to correlate to the corresponding spin contribution of the g‐factors of the U(V) center. This correlation established for the first time offers a direct way to estimate this important ratio from the corresponding g S ‐values, which can be obtained using traditional ab initio packages and hence has a wider application to other {3d–5f} magnets. It is finally shown that the magnetization barrier height is tuned by the splitting of the [U V O 2 ] + 5 f orbitals.