The effect of structural parameters on the exchange coupling constant of the title complexes of Cu(II), Ni(II), and Mn(II) is studied by means of density functional calculations on model compounds. The studied parameters are the bridging M-N-M angle, the M-N bond distance, and the out-of-plane shift of the azido bridge. The model compounds in their most stable geometry, as well as some full molecules in their experimental structures, appear in a high-spin ground state showing ferromagnetic coupling in all cases. The atomic spin density distributions of the model compounds are interpreted as resulting from the interplay between electron delocalization and spin polarization.