The cobalt(II), nickel(II), and copper(II) nitrato-complexes of 1,2-di-(2-pyridyl)-, 1,2-di-(4-pyridyl)-, 1-(2-pyridyl)-2-(3-pyridyl)-, and 1-(2-pyridyl)-2-(4-pyridyl)-ethylene are described, and their structures interpreted on the basis of magnetic and spectral properties. The two main types of complex isolated have stoicheio-metries M(NO3)2L and M(NO3)2L2(L = ligand), the former being co-ordination polymers of the type [M(NO3)2L]n.