Theoretical studies on dicopper(II) complexes of phenoxido-bridged ligands: Magneto-structural correlations

In this work, the magnetic properties of the phenoxido-bridged binuclear copper complex [Cu-2(L-Me,L-Me,L-Me)(2)] were studied using the density functional theory-broken symmetry method by employing various functionals and basis sets, and the magneto-structural correlation was established. Encouraging results were obtained using the wB97X/def2-TZVPP level of theory, as the calculated magnetic coupling constant ( 198.03 cm(-1)) was close to the experimental value (-197.55 cm(-1)). Molecular magnetic orbital and spin density analyses proved that the molecular magnetic orbital is composed of Cu(1)/Cu(2) 3d(z2) orbitals and phenoxido-bridged ligand-conjugated pi-type molecular orbitals, and the paramagnetic centers are dominated by spin delocalization. The magneto-structural correlation proved that the magnetic coupling constant of the complex initially increases and subsequently decreases with increase inthe Cu-O-Cu bond angle (theta). As the bond angle (theta) increases, the character of the exchange is altered from ferromagnetic to antiferromagnetic.