Theoretical studies on magnetic properties of a binuclear paddle wheel Cu(II) complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3)2

Abstract

The magnetic properties of a binuclear copper(II) complex {Cu₂(μ₂-O₂CCH₃)₄}(OCNH₂CH₃)₂ have been investigated on the basis of density functional theory with the broken symmetry (BS) approach. The magnetic coupling constant J values for the investigated complex have been calculated by different methods (HF, m06, PBE, B3LYP, B3PW91, B3P86, BLYP, BPW91, BP86) and basis sets (TZVP, TZV, 6-31G, 6-31++G) for the metal centers, and SVP basis set for the other atoms. The best calculated J value is‒142.6 cm⁻¹, which is in the excellent agreement with the experimental value (J = −101 ± 2 cm⁻¹). By investigating the spin density distribution from the magnetic centers to the atoms of ligands and the singly occupied molecular orbitals (SOMOs) of the Cu(II) ions at the low spin group states, we found that there is a spin delocalization between the Cu(II) ions and acetate ligands.