A series of mono-, di- and tri-nuclear Ni(II) complexes of N, O-donating molecules possessing -H2C-NH- and -HC=N-moieties have been synthesized and characterized and the structures have been determined by single crystal x-ray diffraction. All these exhibited interesting molecular packing in their crystal lattices. Di-nuclear complexes were found to be cleaved in pyridine to result in mononuclear ones with additional coordinations being provided by pyridine. Di-nuclear complexes were found to form urea adducts as demonstrated based on absorption and vibrational studies. © 2002 Elsevier Science B.V. All rights reserved.