Magnetic coupling in end-to-end azido-bridged copper and nickel binuclear complexes: A theoretical study

The influence of structural parameters on the exchange coupling J between m etal atoms in end-to-end azido-bridged binuclear complexes of Cu(II) and NL (II) has been studied by means of density functional calculations. For the case of double-bridged Cu(II) compounds, four ideal pentacoordinate models have been employed in which the coordination spheres of the two metal atoms are either a trigonal bipyramid or a square pyramid, connected through equ atorial or axial bridges. The distortion from those ideal geometries along a Ferry pathway has also been analyzed. For the hexacoordinate Ni(II) compo unds, models with two or one bridging ligands have been studied. The effect of the bridging M-N-N bond angles on the exchange coupling has been analyz ed for both the Cu(II) and Ni(II) complexes.