Regulation mechanism of the solvent coligands on the magnetic properties of azido-Cu(II) complexes by mixed carboxylate/alkanols ligands: A theoretical exploration

Abstract

Combined density functional theory simulations at B1LYP/TZV and broken symmetry approach, have been employed to investigate the magnetic properties of [Cu(4-tfmba)(N3)(CH3OH)]n complexes. Moreover, we reported the theoretical regulation mechanism of the solvent on the magnetic properties of complexes. It is found that the computed magnetic coupling constant (27.34 cm−1) has an excellent correlation with the experimental value (28.11 cm−1) at the mentioned level of theory. In addition, the molecular magnetic orbital and spin population analysis confirm the spin delocalization mechanism of the paramagnetic center Cu(II). We observed that molecular magnetic orbitals are mainly composed of 3dx2-y2 orbitals of paramagnetic center Cu(1) and Cu(2), π-molecular orbitals of μ-1,1-azido and syn,syn-carboxyl, and p-orbitals of a methanol-coordinated oxygen atom. Finally, it is concluded that the magnetic coupling constant of the paramagnetic center Cu(II) increases along with the increase in the electrostatic potential of the molecular surface near the methanol-coordinated oxygen atom. So, the magnitude of magnetic coupling constant decreases along with the increase of the overlap integral of non-orthogonal magnetic orbitals.