In the Cu(II) compound catena-poly[[copper(II)-μ-[2-({2-[2-(naphthalen-2-yloxy)-1-oxidoethylidene]hydrazin-1-ylidene}methyl)phenolato]] dimethylformamide monosolvate monohydrate], {[Cu(C19H14N2O3)]·C3H7NO·H2O}n, (I), the Cu(II) cation is O,N,O'-chelated by one ligand and further N,O-chelated by a second ligand, and exhibits a distorted square-pyramidal coordination environment. The ligand acts as an overall pentadentate bridge between two metal ions, thus forming a novel coordination polymer. In the trinuclear Ni(II) compound diaquabis(1H-imidazole)bis[μ-2-oxido-N'-(1-oxido-2-phenoxyethylidene)benzohydrazidato]trinickel(II) dimethylformamide tetrasolvate, [Ni3(C15H11N2O4)2(C3H4N2)2(H2O)2]·4C3H7NO, (II), the three Ni(II) cations are directly linked by two trans diazine (N-N) bridges and are strictly collinear by symmetry. The central Ni(II) cation, located on an inversion centre, is coordinated by two water O atoms and is further N,O-chelated by two 2-oxido-N'-(1-oxido-2-phenoxyethylidene)benzohydrazidate(3-) ligands in an elongated octahedral coordination geometry. The two terminal centrosymmetrically related Ni(II) cations are coordinated by an imidazole ligand and O,N,O'-chelated by a hydrazidate ligand in a distorted square-planar coordination geometry. Hydrogen bonds link individual molecules of (II) into a chain along [100].