Strong ferromagnetic metal-ligand exchange in a nickel bis(3,5-dipyridylverdazyl)complex

A new 1,5-dipyridyl verdazyl, synthesized from the corresponding dipyridyl hydrazone, coordinates nickel(II) to form a structurally characterized, pseudooctahedral complex analogous to Ni(terpy)(2)(2+). The unusually short Ni-verdazyl distance results in strong ferromagnetic exchange (J(Ni-rad) = + 300, J(rad-rad) = + 160 cm(-1)) between all three paramagnetic species along with a metal-ligand charge transfer band in the electronic spectrum.