Complexes of transition metal ions with the oxygen-nitrogen containing ligand 1,3-bis(2-pyridyl)-1,3-propanedione (bpypH) have been synthesized. These present stoichiometries which do not conform with the usual tendency manifested by β-diketones, since molecular formulas with the composition M(bpyp)X are found. A nitrogen methylated ligand N,N′-dimethyl-1,3-bis(2-pyridyl)-1,3-propanedione methyl sulphate [dimebpypH] (MeSO4)2 has also been synthesized and its complexes with transition metal ions studied. The stoichiometries now, resemble those of typical β-diketones, namely [dimepyp]2MX4 with four anions because of the dicationic nature of the original ligand. This, together with IR evidence suggests a dual type of coordination by bpip via the β-diketone and the pyridyl moieties. © 1988.