Copper(II), nickel(II) and cobalt(II) complexes with N,N '-bis(2-N,N-dimethylaminoethyl)pyridine-2,6-dicarboxamide 1-oxide. Binucleating behaviour bya deprotonated pyridine N-oxide ligand

New copper(II), nickel(II), and cobalt(II) complexes are described with the potentially binucleating pyridine N-oxide ligand N,N'-bis(2-N,N-dimethylam inoethyl)pyridine-2 amide 1-oxide (medpco). Electronic spectra and X-ray po wder diffraction measurements indicate that metal complexes of the type M(m edpco)Hal(2)(H2O)(x) (Hal = Cl, Br) are five-coordinate. Monomeric structur es are proposed with ONN-bonded ligand and coordinated halide. This is anal ogous to the coordination to one of the coppers in the previously reported X-ray structure of Cu-2(medpco)Cl-4. Complexes of the type M-2'(medpco-2H)H al(2)(H2O)(x) (M' = Ni,Co), involving deprotonated ligand, are reported. Th ese appear to have N-oxide-bridged structures, involving binucleating ligan d, analogous to the previously reported X-ray structure of Cu-2(medpco-2H)C l-2. Variable temperature magnetic data for the complexes are discussed.