Electronic and magnetic structure of a triacetylphlorogucinol-bridged -symmetric trinuclear copper complex: Magnetic characterization, ESR spectroscopy, and DFT calculations

For the trinuclear copper complex [Cu3(tapg)(H2bhea)3](ClO 4)3 based on the tritopic bridging ligand 2,4,6-triacetylphlorogucinol (H3tapg) and the capping ligand 2-[bis-(2-hydroxyethyl)amino]ethylamine (H2bhea) a detailed study on the magnetic and electronic properties is presented. The C 3 -symmetric structure of the molecular assembly is preserved in the solid state structure of the compound which crystallizes in the space group R 3 c with a threefold rotation axis passing through the center of the molecule. Susceptibility measurements show weak ferromagnetic interactions with a coupling constant J = 1.10 ( 4 ) cm - 1 mediated by a spin-polarization mechanism. This is confirmed by DFT calculations according the broken symmetry approach at B3LYP/def2-TZVP level of theory. Extended characterization by ESR spectroscopy both in X- and W-band confirm an exchange-coupled system with axial symmetry with g ⊥ = 2.0633 ( 4 ) , g ‖ = 2.2303 ( 4 ) and an effective axial hyperfine constant A ‖ , eff = 64 G .