Beyond Kahn's Model: Substituent and Heteroatom Influence on Exchange Interaction in a Metal-Verdazyl Complex

The synthesis, structure and magnetic properties of the first thiooxoverdazyl metal complex [Cu(hfac)(2)(Svdpy)] [hfac = (1,1,1,5,5,5)-hexafluoroacetylacetonate; Svdpy = 1,5-dimethyl-3-(2-pyridyl)-6-thiooxoverdazyl] is described. The organic radical acts as a bidentate ligand leading to a six-coordinate metal complex. The fit of the thermal variations of the magnetic susceptibility reveal a ferromagnetic intramolecular exchange interaction. This finding is confirmed and analysed by using wavefunction-based methods which indicate that the exchange interaction is governed by the substituent of the radical rather than by its heteroatom.