Abstract
The mechanism responsible for the emergence of ferromagnetic exchange interactions in bischelate complexes of Cu2+ with enaminoketone derivatives of 3-imidazoline nitroxide CuL2 is studied by ab initio quantum chemical methods. The parameters Jcu-L and JL-L’ of exchange interactions between the unpaired electrons of the paramagnetic centers (Cu2+ ion and N-O groups of nitroxyl ligands L and L’) of these complexes were calculated in terms of the full 3x3 configuration interaction between the singlet states constructed in a basis set of molecular orbitals of unpaired electrons. It is shown that for variations of the structure of the coordination polyhedron around the Cu2+ ion from square planar to tetrahedral the exchange interactions between the unpaired electrons of the paramagnetic centers is ferromagnetic JCu-L >JL -L’>0, which agrees with the data of magnetic measurements. The principal mechanism of exchange interactions in CuL2 complexes is the delocalization mechanism that is due to a minor transfer of spin density from the 3d-orbitals of Cu2+ to the Σ-orbitals of the N-O groups of L and L’ ligands.
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Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 5, pp. 850–856, September-October, 1997.
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Musin, R.N., Ovcharenko, I.V., Ohrström, L. et al. Magnetic properties of Cu(II) bischelate complexes with 3-imidazoline nitroxides. 2. Anab initio analysis of exchange interaction mechanisms. J Struct Chem 38, 711–715 (1997). https://doi.org/10.1007/BF02763882
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DOI: https://doi.org/10.1007/BF02763882