A pentadentate phenol-containing ligand (H 3 L) with N 2 O 3 donor atoms yields Ni II 2 (1), Ni II 4 (2), Cu II 2 (3) and Cu II 4 (4) complexes, which have been structurally characterized by X-ray diffraction. Complex 1 contains a single-atom O-bridged urea. The compounds were characterized by IR, UV/Vis, mass spectrometry, electrochemistry and variable-temperature (2−295 K) magnetic susceptibility measurements. Analysis of the susceptibility data shows antiferromagnetic interactions between the metal centers indicating a diamagnetic ground state for complexes 1, 3 and 4, whereas complex 2, a tetranuclear Ni II cubane, has a complicated low-lying mag-Eur.